--- /dev/null
+/*
+ * kernel/workqueue.c - generic async execution with shared worker pool
+ *
+ * Copyright (C) 2002 Ingo Molnar
+ *
+ * Derived from the taskqueue/keventd code by:
+ * David Woodhouse <dwmw2@infradead.org>
+ * Andrew Morton
+ * Kai Petzke <wpp@marie.physik.tu-berlin.de>
+ * Theodore Ts'o <tytso@mit.edu>
+ *
+ * Made to use alloc_percpu by Christoph Lameter.
+ *
+ * Copyright (C) 2010 SUSE Linux Products GmbH
+ * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
+ *
+ * This is the generic async execution mechanism. Work items as are
+ * executed in process context. The worker pool is shared and
+ * automatically managed. There are two worker pools for each CPU (one for
+ * normal work items and the other for high priority ones) and some extra
+ * pools for workqueues which are not bound to any specific CPU - the
+ * number of these backing pools is dynamic.
+ *
+ * Please read Documentation/workqueue.txt for details.
+ */
+
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/completion.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+#include <linux/hardirq.h>
+#include <linux/mempolicy.h>
+#include <linux/freezer.h>
+#include <linux/kallsyms.h>
+#include <linux/debug_locks.h>
+#include <linux/lockdep.h>
+#include <linux/idr.h>
+#include <linux/jhash.h>
+#include <linux/hashtable.h>
+#include <linux/rculist.h>
+#include <linux/nodemask.h>
+#include <linux/moduleparam.h>
+#include <linux/uaccess.h>
+#include <linux/locallock.h>
+#include <linux/delay.h>
+
+#include "workqueue_internal.h"
+
+enum {
+ /*
+ * worker_pool flags
+ *
+ * A bound pool is either associated or disassociated with its CPU.
+ * While associated (!DISASSOCIATED), all workers are bound to the
+ * CPU and none has %WORKER_UNBOUND set and concurrency management
+ * is in effect.
+ *
+ * While DISASSOCIATED, the cpu may be offline and all workers have
+ * %WORKER_UNBOUND set and concurrency management disabled, and may
+ * be executing on any CPU. The pool behaves as an unbound one.
+ *
+ * Note that DISASSOCIATED should be flipped only while holding
+ * attach_mutex to avoid changing binding state while
+ * worker_attach_to_pool() is in progress.
+ */
+ POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
+
+ /* worker flags */
+ WORKER_DIE = 1 << 1, /* die die die */
+ WORKER_IDLE = 1 << 2, /* is idle */
+ WORKER_PREP = 1 << 3, /* preparing to run works */
+ WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
+ WORKER_UNBOUND = 1 << 7, /* worker is unbound */
+ WORKER_REBOUND = 1 << 8, /* worker was rebound */
+
+ WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
+ WORKER_UNBOUND | WORKER_REBOUND,
+
+ NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
+
+ UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
+ BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
+
+ MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
+ IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
+
+ MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
+ /* call for help after 10ms
+ (min two ticks) */
+ MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
+ CREATE_COOLDOWN = HZ, /* time to breath after fail */
+
+ /*
+ * Rescue workers are used only on emergencies and shared by
+ * all cpus. Give MIN_NICE.
+ */
+ RESCUER_NICE_LEVEL = MIN_NICE,
+ HIGHPRI_NICE_LEVEL = MIN_NICE,
+
+ WQ_NAME_LEN = 24,
+};
+
+/*
+ * Structure fields follow one of the following exclusion rules.
+ *
+ * I: Modifiable by initialization/destruction paths and read-only for
+ * everyone else.
+ *
+ * P: Preemption protected. Disabling preemption is enough and should
+ * only be modified and accessed from the local cpu.
+ *
+ * L: pool->lock protected. Access with pool->lock held.
+ *
+ * X: During normal operation, modification requires pool->lock and should
+ * be done only from local cpu. Either disabling preemption on local
+ * cpu or grabbing pool->lock is enough for read access. If
+ * POOL_DISASSOCIATED is set, it's identical to L.
+ *
+ * On RT we need the extra protection via rt_lock_idle_list() for
+ * the list manipulations against read access from
+ * wq_worker_sleeping(). All other places are nicely serialized via
+ * pool->lock.
+ *
+ * A: pool->attach_mutex protected.
+ *
+ * PL: wq_pool_mutex protected.
+ *
+ * PR: wq_pool_mutex protected for writes. RCU protected for reads.
+ *
+ * WQ: wq->mutex protected.
+ *
+ * WR: wq->mutex protected for writes. RCU protected for reads.
+ *
+ * MD: wq_mayday_lock protected.
+ */
+
+/* struct worker is defined in workqueue_internal.h */
+
+struct worker_pool {
+ spinlock_t lock; /* the pool lock */
+ int cpu; /* I: the associated cpu */
+ int node; /* I: the associated node ID */
+ int id; /* I: pool ID */
+ unsigned int flags; /* X: flags */
+
+ struct list_head worklist; /* L: list of pending works */
+ int nr_workers; /* L: total number of workers */
+
+ /* nr_idle includes the ones off idle_list for rebinding */
+ int nr_idle; /* L: currently idle ones */
+
+ struct list_head idle_list; /* X: list of idle workers */
+ struct timer_list idle_timer; /* L: worker idle timeout */
+ struct timer_list mayday_timer; /* L: SOS timer for workers */
+
+ /* a workers is either on busy_hash or idle_list, or the manager */
+ DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
+ /* L: hash of busy workers */
+
+ /* see manage_workers() for details on the two manager mutexes */
+ struct mutex manager_arb; /* manager arbitration */
+ struct worker *manager; /* L: purely informational */
+ struct mutex attach_mutex; /* attach/detach exclusion */
+ struct list_head workers; /* A: attached workers */
+ struct completion *detach_completion; /* all workers detached */
+
+ struct ida worker_ida; /* worker IDs for task name */
+
+ struct workqueue_attrs *attrs; /* I: worker attributes */
+ struct hlist_node hash_node; /* PL: unbound_pool_hash node */
+ int refcnt; /* PL: refcnt for unbound pools */
+
+ /*
+ * The current concurrency level. As it's likely to be accessed
+ * from other CPUs during try_to_wake_up(), put it in a separate
+ * cacheline.
+ */
+ atomic_t nr_running ____cacheline_aligned_in_smp;
+
+ /*
+ * Destruction of pool is RCU protected to allow dereferences
+ * from get_work_pool().
+ */
+ struct rcu_head rcu;
+} ____cacheline_aligned_in_smp;
+
+/*
+ * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
+ * of work_struct->data are used for flags and the remaining high bits
+ * point to the pwq; thus, pwqs need to be aligned at two's power of the
+ * number of flag bits.
+ */
+struct pool_workqueue {
+ struct worker_pool *pool; /* I: the associated pool */
+ struct workqueue_struct *wq; /* I: the owning workqueue */
+ int work_color; /* L: current color */
+ int flush_color; /* L: flushing color */
+ int refcnt; /* L: reference count */
+ int nr_in_flight[WORK_NR_COLORS];
+ /* L: nr of in_flight works */
+ int nr_active; /* L: nr of active works */
+ int max_active; /* L: max active works */
+ struct list_head delayed_works; /* L: delayed works */
+ struct list_head pwqs_node; /* WR: node on wq->pwqs */
+ struct list_head mayday_node; /* MD: node on wq->maydays */
+
+ /*
+ * Release of unbound pwq is punted to system_wq. See put_pwq()
+ * and pwq_unbound_release_workfn() for details. pool_workqueue
+ * itself is also RCU protected so that the first pwq can be
+ * determined without grabbing wq->mutex.
+ */
+ struct work_struct unbound_release_work;
+ struct rcu_head rcu;
+} __aligned(1 << WORK_STRUCT_FLAG_BITS);
+
+/*
+ * Structure used to wait for workqueue flush.
+ */
+struct wq_flusher {
+ struct list_head list; /* WQ: list of flushers */
+ int flush_color; /* WQ: flush color waiting for */
+ struct completion done; /* flush completion */
+};
+
+struct wq_device;
+
+/*
+ * The externally visible workqueue. It relays the issued work items to
+ * the appropriate worker_pool through its pool_workqueues.
+ */
+struct workqueue_struct {
+ struct list_head pwqs; /* WR: all pwqs of this wq */
+ struct list_head list; /* PR: list of all workqueues */
+
+ struct mutex mutex; /* protects this wq */
+ int work_color; /* WQ: current work color */
+ int flush_color; /* WQ: current flush color */
+ atomic_t nr_pwqs_to_flush; /* flush in progress */
+ struct wq_flusher *first_flusher; /* WQ: first flusher */
+ struct list_head flusher_queue; /* WQ: flush waiters */
+ struct list_head flusher_overflow; /* WQ: flush overflow list */
+
+ struct list_head maydays; /* MD: pwqs requesting rescue */
+ struct worker *rescuer; /* I: rescue worker */
+
+ int nr_drainers; /* WQ: drain in progress */
+ int saved_max_active; /* WQ: saved pwq max_active */
+
+ struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */
+ struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */
+
+#ifdef CONFIG_SYSFS
+ struct wq_device *wq_dev; /* I: for sysfs interface */
+#endif
+#ifdef CONFIG_LOCKDEP
+ struct lockdep_map lockdep_map;
+#endif
+ char name[WQ_NAME_LEN]; /* I: workqueue name */
+
+ /*
+ * Destruction of workqueue_struct is sched-RCU protected to allow
+ * walking the workqueues list without grabbing wq_pool_mutex.
+ * This is used to dump all workqueues from sysrq.
+ */
+ struct rcu_head rcu;
+
+ /* hot fields used during command issue, aligned to cacheline */
+ unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
+ struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */
+ struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */
+};
+
+static struct kmem_cache *pwq_cache;
+
+static cpumask_var_t *wq_numa_possible_cpumask;
+ /* possible CPUs of each node */
+
+static bool wq_disable_numa;
+module_param_named(disable_numa, wq_disable_numa, bool, 0444);
+
+/* see the comment above the definition of WQ_POWER_EFFICIENT */
+#ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
+static bool wq_power_efficient = true;
+#else
+static bool wq_power_efficient;
+#endif
+
+module_param_named(power_efficient, wq_power_efficient, bool, 0444);
+
+static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
+
+/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
+static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
+
+static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
+static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
+
+static LIST_HEAD(workqueues); /* PR: list of all workqueues */
+static bool workqueue_freezing; /* PL: have wqs started freezing? */
+
+/* the per-cpu worker pools */
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
+ cpu_worker_pools);
+
+static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
+
+/* PL: hash of all unbound pools keyed by pool->attrs */
+static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
+
+/* I: attributes used when instantiating standard unbound pools on demand */
+static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
+
+/* I: attributes used when instantiating ordered pools on demand */
+static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
+
+struct workqueue_struct *system_wq __read_mostly;
+EXPORT_SYMBOL(system_wq);
+struct workqueue_struct *system_highpri_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_highpri_wq);
+struct workqueue_struct *system_long_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_long_wq);
+struct workqueue_struct *system_unbound_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_unbound_wq);
+struct workqueue_struct *system_freezable_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_freezable_wq);
+struct workqueue_struct *system_power_efficient_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_power_efficient_wq);
+struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
+
+static DEFINE_LOCAL_IRQ_LOCK(pendingb_lock);
+
+static int worker_thread(void *__worker);
+static void copy_workqueue_attrs(struct workqueue_attrs *to,
+ const struct workqueue_attrs *from);
+static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/workqueue.h>
+
+#define assert_rcu_or_pool_mutex() \
+ rcu_lockdep_assert(rcu_read_lock_held() || \
+ lockdep_is_held(&wq_pool_mutex), \
+ "RCU or wq_pool_mutex should be held")
+
+#define assert_rcu_or_wq_mutex(wq) \
+ rcu_lockdep_assert(rcu_read_lock_held() || \
+ lockdep_is_held(&wq->mutex), \
+ "RCU or wq->mutex should be held")
+
+#define for_each_cpu_worker_pool(pool, cpu) \
+ for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
+ (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
+ (pool)++)
+
+/**
+ * for_each_pool - iterate through all worker_pools in the system
+ * @pool: iteration cursor
+ * @pi: integer used for iteration
+ *
+ * This must be called either with wq_pool_mutex held or RCU read
+ * locked. If the pool needs to be used beyond the locking in effect, the
+ * caller is responsible for guaranteeing that the pool stays online.
+ *
+ * The if/else clause exists only for the lockdep assertion and can be
+ * ignored.
+ */
+#define for_each_pool(pool, pi) \
+ idr_for_each_entry(&worker_pool_idr, pool, pi) \
+ if (({ assert_rcu_or_pool_mutex(); false; })) { } \
+ else
+
+/**
+ * for_each_pool_worker - iterate through all workers of a worker_pool
+ * @worker: iteration cursor
+ * @pool: worker_pool to iterate workers of
+ *
+ * This must be called with @pool->attach_mutex.
+ *
+ * The if/else clause exists only for the lockdep assertion and can be
+ * ignored.
+ */
+#define for_each_pool_worker(worker, pool) \
+ list_for_each_entry((worker), &(pool)->workers, node) \
+ if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
+ else
+
+/**
+ * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
+ * @pwq: iteration cursor
+ * @wq: the target workqueue
+ *
+ * This must be called either with wq->mutex held or RCU read locked.
+ * If the pwq needs to be used beyond the locking in effect, the caller is
+ * responsible for guaranteeing that the pwq stays online.
+ *
+ * The if/else clause exists only for the lockdep assertion and can be
+ * ignored.
+ */
+#define for_each_pwq(pwq, wq) \
+ list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
+ if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
+ else
+
+#ifdef CONFIG_PREEMPT_RT_BASE
+static inline void rt_lock_idle_list(struct worker_pool *pool)
+{
+ preempt_disable();
+}
+static inline void rt_unlock_idle_list(struct worker_pool *pool)
+{
+ preempt_enable();
+}
+static inline void sched_lock_idle_list(struct worker_pool *pool) { }
+static inline void sched_unlock_idle_list(struct worker_pool *pool) { }
+#else
+static inline void rt_lock_idle_list(struct worker_pool *pool) { }
+static inline void rt_unlock_idle_list(struct worker_pool *pool) { }
+static inline void sched_lock_idle_list(struct worker_pool *pool)
+{
+ spin_lock_irq(&pool->lock);
+}
+static inline void sched_unlock_idle_list(struct worker_pool *pool)
+{
+ spin_unlock_irq(&pool->lock);
+}
+#endif
+
+
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+
+static struct debug_obj_descr work_debug_descr;
+
+static void *work_debug_hint(void *addr)
+{
+ return ((struct work_struct *) addr)->func;
+}
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int work_fixup_init(void *addr, enum debug_obj_state state)
+{
+ struct work_struct *work = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ cancel_work_sync(work);
+ debug_object_init(work, &work_debug_descr);
+ return 1;
+ default:
+ return 0;
+ }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
+ */
+static int work_fixup_activate(void *addr, enum debug_obj_state state)
+{
+ struct work_struct *work = addr;
+
+ switch (state) {
+
+ case ODEBUG_STATE_NOTAVAILABLE:
+ /*
+ * This is not really a fixup. The work struct was
+ * statically initialized. We just make sure that it
+ * is tracked in the object tracker.
+ */
+ if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
+ debug_object_init(work, &work_debug_descr);
+ debug_object_activate(work, &work_debug_descr);
+ return 0;
+ }
+ WARN_ON_ONCE(1);
+ return 0;
+
+ case ODEBUG_STATE_ACTIVE:
+ WARN_ON(1);
+
+ default:
+ return 0;
+ }
+}
+
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static int work_fixup_free(void *addr, enum debug_obj_state state)
+{
+ struct work_struct *work = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ cancel_work_sync(work);
+ debug_object_free(work, &work_debug_descr);
+ return 1;
+ default:
+ return 0;
+ }
+}
+
+static struct debug_obj_descr work_debug_descr = {
+ .name = "work_struct",
+ .debug_hint = work_debug_hint,
+ .fixup_init = work_fixup_init,
+ .fixup_activate = work_fixup_activate,
+ .fixup_free = work_fixup_free,
+};
+
+static inline void debug_work_activate(struct work_struct *work)
+{
+ debug_object_activate(work, &work_debug_descr);
+}
+
+static inline void debug_work_deactivate(struct work_struct *work)
+{
+ debug_object_deactivate(work, &work_debug_descr);
+}
+
+void __init_work(struct work_struct *work, int onstack)
+{
+ if (onstack)
+ debug_object_init_on_stack(work, &work_debug_descr);
+ else
+ debug_object_init(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(__init_work);
+
+void destroy_work_on_stack(struct work_struct *work)
+{
+ debug_object_free(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_work_on_stack);
+
+void destroy_delayed_work_on_stack(struct delayed_work *work)
+{
+ destroy_timer_on_stack(&work->timer);
+ debug_object_free(&work->work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
+
+#else
+static inline void debug_work_activate(struct work_struct *work) { }
+static inline void debug_work_deactivate(struct work_struct *work) { }
+#endif
+
+/**
+ * worker_pool_assign_id - allocate ID and assing it to @pool
+ * @pool: the pool pointer of interest
+ *
+ * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
+ * successfully, -errno on failure.
+ */
+static int worker_pool_assign_id(struct worker_pool *pool)
+{
+ int ret;
+
+ lockdep_assert_held(&wq_pool_mutex);
+
+ ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
+ GFP_KERNEL);
+ if (ret >= 0) {
+ pool->id = ret;
+ return 0;
+ }
+ return ret;
+}
+
+/**
+ * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
+ * @wq: the target workqueue
+ * @node: the node ID
+ *
+ * This must be called either with pwq_lock held or RCU read locked.
+ * If the pwq needs to be used beyond the locking in effect, the caller is
+ * responsible for guaranteeing that the pwq stays online.
+ *
+ * Return: The unbound pool_workqueue for @node.
+ */
+static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
+ int node)
+{
+ assert_rcu_or_wq_mutex(wq);
+ return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
+}
+
+static unsigned int work_color_to_flags(int color)
+{
+ return color << WORK_STRUCT_COLOR_SHIFT;
+}
+
+static int get_work_color(struct work_struct *work)
+{
+ return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
+ ((1 << WORK_STRUCT_COLOR_BITS) - 1);
+}
+
+static int work_next_color(int color)
+{
+ return (color + 1) % WORK_NR_COLORS;
+}
+
+/*
+ * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
+ * contain the pointer to the queued pwq. Once execution starts, the flag
+ * is cleared and the high bits contain OFFQ flags and pool ID.
+ *
+ * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
+ * and clear_work_data() can be used to set the pwq, pool or clear
+ * work->data. These functions should only be called while the work is
+ * owned - ie. while the PENDING bit is set.
+ *
+ * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
+ * corresponding to a work. Pool is available once the work has been
+ * queued anywhere after initialization until it is sync canceled. pwq is
+ * available only while the work item is queued.
+ *
+ * %WORK_OFFQ_CANCELING is used to mark a work item which is being
+ * canceled. While being canceled, a work item may have its PENDING set
+ * but stay off timer and worklist for arbitrarily long and nobody should
+ * try to steal the PENDING bit.
+ */
+static inline void set_work_data(struct work_struct *work, unsigned long data,
+ unsigned long flags)
+{
+ WARN_ON_ONCE(!work_pending(work));
+ atomic_long_set(&work->data, data | flags | work_static(work));
+}
+
+static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
+ unsigned long extra_flags)
+{
+ set_work_data(work, (unsigned long)pwq,
+ WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
+}
+
+static void set_work_pool_and_keep_pending(struct work_struct *work,
+ int pool_id)
+{
+ set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
+ WORK_STRUCT_PENDING);
+}
+
+static void set_work_pool_and_clear_pending(struct work_struct *work,
+ int pool_id)
+{
+ /*
+ * The following wmb is paired with the implied mb in
+ * test_and_set_bit(PENDING) and ensures all updates to @work made
+ * here are visible to and precede any updates by the next PENDING
+ * owner.
+ */
+ smp_wmb();
+ set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
+}
+
+static void clear_work_data(struct work_struct *work)
+{
+ smp_wmb(); /* see set_work_pool_and_clear_pending() */
+ set_work_data(work, WORK_STRUCT_NO_POOL, 0);
+}
+
+static struct pool_workqueue *get_work_pwq(struct work_struct *work)
+{
+ unsigned long data = atomic_long_read(&work->data);
+
+ if (data & WORK_STRUCT_PWQ)
+ return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
+ else
+ return NULL;
+}
+
+/**
+ * get_work_pool - return the worker_pool a given work was associated with
+ * @work: the work item of interest
+ *
+ * Pools are created and destroyed under wq_pool_mutex, and allows read
+ * access under RCU read lock. As such, this function should be
+ * called under wq_pool_mutex or inside of a rcu_read_lock() region.
+ *
+ * All fields of the returned pool are accessible as long as the above
+ * mentioned locking is in effect. If the returned pool needs to be used
+ * beyond the critical section, the caller is responsible for ensuring the
+ * returned pool is and stays online.
+ *
+ * Return: The worker_pool @work was last associated with. %NULL if none.
+ */
+static struct worker_pool *get_work_pool(struct work_struct *work)
+{
+ unsigned long data = atomic_long_read(&work->data);
+ int pool_id;
+
+ assert_rcu_or_pool_mutex();
+
+ if (data & WORK_STRUCT_PWQ)
+ return ((struct pool_workqueue *)
+ (data & WORK_STRUCT_WQ_DATA_MASK))->pool;
+
+ pool_id = data >> WORK_OFFQ_POOL_SHIFT;
+ if (pool_id == WORK_OFFQ_POOL_NONE)
+ return NULL;
+
+ return idr_find(&worker_pool_idr, pool_id);
+}
+
+/**
+ * get_work_pool_id - return the worker pool ID a given work is associated with
+ * @work: the work item of interest
+ *
+ * Return: The worker_pool ID @work was last associated with.
+ * %WORK_OFFQ_POOL_NONE if none.
+ */
+static int get_work_pool_id(struct work_struct *work)
+{
+ unsigned long data = atomic_long_read(&work->data);
+
+ if (data & WORK_STRUCT_PWQ)
+ return ((struct pool_workqueue *)
+ (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
+
+ return data >> WORK_OFFQ_POOL_SHIFT;
+}
+
+static void mark_work_canceling(struct work_struct *work)
+{
+ unsigned long pool_id = get_work_pool_id(work);
+
+ pool_id <<= WORK_OFFQ_POOL_SHIFT;
+ set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
+}
+
+static bool work_is_canceling(struct work_struct *work)
+{
+ unsigned long data = atomic_long_read(&work->data);
+
+ return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
+}
+
+/*
+ * Policy functions. These define the policies on how the global worker
+ * pools are managed. Unless noted otherwise, these functions assume that
+ * they're being called with pool->lock held.
+ */
+
+static bool __need_more_worker(struct worker_pool *pool)
+{
+ return !atomic_read(&pool->nr_running);
+}
+
+/*
+ * Need to wake up a worker? Called from anything but currently
+ * running workers.
+ *
+ * Note that, because unbound workers never contribute to nr_running, this
+ * function will always return %true for unbound pools as long as the
+ * worklist isn't empty.
+ */
+static bool need_more_worker(struct worker_pool *pool)
+{
+ return !list_empty(&pool->worklist) && __need_more_worker(pool);
+}
+
+/* Can I start working? Called from busy but !running workers. */
+static bool may_start_working(struct worker_pool *pool)
+{
+ return pool->nr_idle;
+}
+
+/* Do I need to keep working? Called from currently running workers. */
+static bool keep_working(struct worker_pool *pool)
+{
+ return !list_empty(&pool->worklist) &&
+ atomic_read(&pool->nr_running) <= 1;
+}
+
+/* Do we need a new worker? Called from manager. */
+static bool need_to_create_worker(struct worker_pool *pool)
+{
+ return need_more_worker(pool) && !may_start_working(pool);
+}
+
+/* Do we have too many workers and should some go away? */
+static bool too_many_workers(struct worker_pool *pool)
+{
+ bool managing = mutex_is_locked(&pool->manager_arb);
+ int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
+ int nr_busy = pool->nr_workers - nr_idle;
+
+ return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
+}
+
+/*
+ * Wake up functions.
+ */
+
+/* Return the first idle worker. Safe with preemption disabled */
+static struct worker *first_idle_worker(struct worker_pool *pool)
+{
+ if (unlikely(list_empty(&pool->idle_list)))
+ return NULL;
+
+ return list_first_entry(&pool->idle_list, struct worker, entry);
+}
+
+/**
+ * wake_up_worker - wake up an idle worker
+ * @pool: worker pool to wake worker from
+ *
+ * Wake up the first idle worker of @pool.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ */
+static void wake_up_worker(struct worker_pool *pool)
+{
+ struct worker *worker;
+
+ rt_lock_idle_list(pool);
+
+ worker = first_idle_worker(pool);
+
+ if (likely(worker))
+ wake_up_process(worker->task);
+
+ rt_unlock_idle_list(pool);
+}
+
+/**
+ * wq_worker_running - a worker is running again
+ * @task: task returning from sleep
+ *
+ * This function is called when a worker returns from schedule()
+ */
+void wq_worker_running(struct task_struct *task)
+{
+ struct worker *worker = kthread_data(task);
+
+ if (!worker->sleeping)
+ return;
+ if (!(worker->flags & WORKER_NOT_RUNNING))
+ atomic_inc(&worker->pool->nr_running);
+ worker->sleeping = 0;
+}
+
+/**
+ * wq_worker_sleeping - a worker is going to sleep
+ * @task: task going to sleep
+ * This function is called from schedule() when a busy worker is
+ * going to sleep.
+ */
+void wq_worker_sleeping(struct task_struct *task)
+{
+ struct worker *worker = kthread_data(task);
+ struct worker_pool *pool;
+
+ /*
+ * Rescuers, which may not have all the fields set up like normal
+ * workers, also reach here, let's not access anything before
+ * checking NOT_RUNNING.
+ */
+ if (worker->flags & WORKER_NOT_RUNNING)
+ return;
+
+ pool = worker->pool;
+
+ if (WARN_ON_ONCE(worker->sleeping))
+ return;
+
+ worker->sleeping = 1;
+
+ /*
+ * The counterpart of the following dec_and_test, implied mb,
+ * worklist not empty test sequence is in insert_work().
+ * Please read comment there.
+ */
+ if (atomic_dec_and_test(&pool->nr_running) &&
+ !list_empty(&pool->worklist)) {
+ sched_lock_idle_list(pool);
+ wake_up_worker(pool);
+ sched_unlock_idle_list(pool);
+ }
+}
+
+/**
+ * worker_set_flags - set worker flags and adjust nr_running accordingly
+ * @worker: self
+ * @flags: flags to set
+ *
+ * Set @flags in @worker->flags and adjust nr_running accordingly.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock)
+ */
+static inline void worker_set_flags(struct worker *worker, unsigned int flags)
+{
+ struct worker_pool *pool = worker->pool;
+
+ WARN_ON_ONCE(worker->task != current);
+
+ /* If transitioning into NOT_RUNNING, adjust nr_running. */
+ if ((flags & WORKER_NOT_RUNNING) &&
+ !(worker->flags & WORKER_NOT_RUNNING)) {
+ atomic_dec(&pool->nr_running);
+ }
+
+ worker->flags |= flags;
+}
+
+/**
+ * worker_clr_flags - clear worker flags and adjust nr_running accordingly
+ * @worker: self
+ * @flags: flags to clear
+ *
+ * Clear @flags in @worker->flags and adjust nr_running accordingly.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock)
+ */
+static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
+{
+ struct worker_pool *pool = worker->pool;
+ unsigned int oflags = worker->flags;
+
+ WARN_ON_ONCE(worker->task != current);
+
+ worker->flags &= ~flags;
+
+ /*
+ * If transitioning out of NOT_RUNNING, increment nr_running. Note
+ * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
+ * of multiple flags, not a single flag.
+ */
+ if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
+ if (!(worker->flags & WORKER_NOT_RUNNING))
+ atomic_inc(&pool->nr_running);
+}
+
+/**
+ * find_worker_executing_work - find worker which is executing a work
+ * @pool: pool of interest
+ * @work: work to find worker for
+ *
+ * Find a worker which is executing @work on @pool by searching
+ * @pool->busy_hash which is keyed by the address of @work. For a worker
+ * to match, its current execution should match the address of @work and
+ * its work function. This is to avoid unwanted dependency between
+ * unrelated work executions through a work item being recycled while still
+ * being executed.
+ *
+ * This is a bit tricky. A work item may be freed once its execution
+ * starts and nothing prevents the freed area from being recycled for
+ * another work item. If the same work item address ends up being reused
+ * before the original execution finishes, workqueue will identify the
+ * recycled work item as currently executing and make it wait until the
+ * current execution finishes, introducing an unwanted dependency.
+ *
+ * This function checks the work item address and work function to avoid
+ * false positives. Note that this isn't complete as one may construct a
+ * work function which can introduce dependency onto itself through a
+ * recycled work item. Well, if somebody wants to shoot oneself in the
+ * foot that badly, there's only so much we can do, and if such deadlock
+ * actually occurs, it should be easy to locate the culprit work function.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ *
+ * Return:
+ * Pointer to worker which is executing @work if found, %NULL
+ * otherwise.
+ */
+static struct worker *find_worker_executing_work(struct worker_pool *pool,
+ struct work_struct *work)
+{
+ struct worker *worker;
+
+ hash_for_each_possible(pool->busy_hash, worker, hentry,
+ (unsigned long)work)
+ if (worker->current_work == work &&
+ worker->current_func == work->func)
+ return worker;
+
+ return NULL;
+}
+
+/**
+ * move_linked_works - move linked works to a list
+ * @work: start of series of works to be scheduled
+ * @head: target list to append @work to
+ * @nextp: out paramter for nested worklist walking
+ *
+ * Schedule linked works starting from @work to @head. Work series to
+ * be scheduled starts at @work and includes any consecutive work with
+ * WORK_STRUCT_LINKED set in its predecessor.
+ *
+ * If @nextp is not NULL, it's updated to point to the next work of
+ * the last scheduled work. This allows move_linked_works() to be
+ * nested inside outer list_for_each_entry_safe().
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ */
+static void move_linked_works(struct work_struct *work, struct list_head *head,
+ struct work_struct **nextp)
+{
+ struct work_struct *n;
+
+ /*
+ * Linked worklist will always end before the end of the list,
+ * use NULL for list head.
+ */
+ list_for_each_entry_safe_from(work, n, NULL, entry) {
+ list_move_tail(&work->entry, head);
+ if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
+ break;
+ }
+
+ /*
+ * If we're already inside safe list traversal and have moved
+ * multiple works to the scheduled queue, the next position
+ * needs to be updated.
+ */
+ if (nextp)
+ *nextp = n;
+}
+
+/**
+ * get_pwq - get an extra reference on the specified pool_workqueue
+ * @pwq: pool_workqueue to get
+ *
+ * Obtain an extra reference on @pwq. The caller should guarantee that
+ * @pwq has positive refcnt and be holding the matching pool->lock.
+ */
+static void get_pwq(struct pool_workqueue *pwq)
+{
+ lockdep_assert_held(&pwq->pool->lock);
+ WARN_ON_ONCE(pwq->refcnt <= 0);
+ pwq->refcnt++;
+}
+
+/**
+ * put_pwq - put a pool_workqueue reference
+ * @pwq: pool_workqueue to put
+ *
+ * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
+ * destruction. The caller should be holding the matching pool->lock.
+ */
+static void put_pwq(struct pool_workqueue *pwq)
+{
+ lockdep_assert_held(&pwq->pool->lock);
+ if (likely(--pwq->refcnt))
+ return;
+ if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
+ return;
+ /*
+ * @pwq can't be released under pool->lock, bounce to
+ * pwq_unbound_release_workfn(). This never recurses on the same
+ * pool->lock as this path is taken only for unbound workqueues and
+ * the release work item is scheduled on a per-cpu workqueue. To
+ * avoid lockdep warning, unbound pool->locks are given lockdep
+ * subclass of 1 in get_unbound_pool().
+ */
+ schedule_work(&pwq->unbound_release_work);
+}
+
+/**
+ * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
+ * @pwq: pool_workqueue to put (can be %NULL)
+ *
+ * put_pwq() with locking. This function also allows %NULL @pwq.
+ */
+static void put_pwq_unlocked(struct pool_workqueue *pwq)
+{
+ if (pwq) {
+ /*
+ * As both pwqs and pools are RCU protected, the
+ * following lock operations are safe.
+ */
+ local_spin_lock_irq(pendingb_lock, &pwq->pool->lock);
+ put_pwq(pwq);
+ local_spin_unlock_irq(pendingb_lock, &pwq->pool->lock);
+ }
+}
+
+static void pwq_activate_delayed_work(struct work_struct *work)
+{
+ struct pool_workqueue *pwq = get_work_pwq(work);
+
+ trace_workqueue_activate_work(work);
+ move_linked_works(work, &pwq->pool->worklist, NULL);
+ __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
+ pwq->nr_active++;
+}
+
+static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
+{
+ struct work_struct *work = list_first_entry(&pwq->delayed_works,
+ struct work_struct, entry);
+
+ pwq_activate_delayed_work(work);
+}
+
+/**
+ * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
+ * @pwq: pwq of interest
+ * @color: color of work which left the queue
+ *
+ * A work either has completed or is removed from pending queue,
+ * decrement nr_in_flight of its pwq and handle workqueue flushing.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ */
+static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
+{
+ /* uncolored work items don't participate in flushing or nr_active */
+ if (color == WORK_NO_COLOR)
+ goto out_put;
+
+ pwq->nr_in_flight[color]--;
+
+ pwq->nr_active--;
+ if (!list_empty(&pwq->delayed_works)) {
+ /* one down, submit a delayed one */
+ if (pwq->nr_active < pwq->max_active)
+ pwq_activate_first_delayed(pwq);
+ }
+
+ /* is flush in progress and are we at the flushing tip? */
+ if (likely(pwq->flush_color != color))
+ goto out_put;
+
+ /* are there still in-flight works? */
+ if (pwq->nr_in_flight[color])
+ goto out_put;
+
+ /* this pwq is done, clear flush_color */
+ pwq->flush_color = -1;
+
+ /*
+ * If this was the last pwq, wake up the first flusher. It
+ * will handle the rest.
+ */
+ if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
+ complete(&pwq->wq->first_flusher->done);
+out_put:
+ put_pwq(pwq);
+}
+
+/**
+ * try_to_grab_pending - steal work item from worklist and disable irq
+ * @work: work item to steal
+ * @is_dwork: @work is a delayed_work
+ * @flags: place to store irq state
+ *
+ * Try to grab PENDING bit of @work. This function can handle @work in any
+ * stable state - idle, on timer or on worklist.
+ *
+ * Return:
+ * 1 if @work was pending and we successfully stole PENDING
+ * 0 if @work was idle and we claimed PENDING
+ * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
+ * -ENOENT if someone else is canceling @work, this state may persist
+ * for arbitrarily long
+ *
+ * Note:
+ * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
+ * interrupted while holding PENDING and @work off queue, irq must be
+ * disabled on entry. This, combined with delayed_work->timer being
+ * irqsafe, ensures that we return -EAGAIN for finite short period of time.
+ *
+ * On successful return, >= 0, irq is disabled and the caller is
+ * responsible for releasing it using local_irq_restore(*@flags).
+ *
+ * This function is safe to call from any context including IRQ handler.
+ */
+static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
+ unsigned long *flags)
+{
+ struct worker_pool *pool;
+ struct pool_workqueue *pwq;
+
+ local_lock_irqsave(pendingb_lock, *flags);
+
+ /* try to steal the timer if it exists */
+ if (is_dwork) {
+ struct delayed_work *dwork = to_delayed_work(work);
+
+ /*
+ * dwork->timer is irqsafe. If del_timer() fails, it's
+ * guaranteed that the timer is not queued anywhere and not
+ * running on the local CPU.
+ */
+ if (likely(del_timer(&dwork->timer)))
+ return 1;
+ }
+
+ /* try to claim PENDING the normal way */
+ if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
+ return 0;
+
+ rcu_read_lock();
+ /*
+ * The queueing is in progress, or it is already queued. Try to
+ * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
+ */
+ pool = get_work_pool(work);
+ if (!pool)
+ goto fail;
+
+ spin_lock(&pool->lock);
+ /*
+ * work->data is guaranteed to point to pwq only while the work
+ * item is queued on pwq->wq, and both updating work->data to point
+ * to pwq on queueing and to pool on dequeueing are done under
+ * pwq->pool->lock. This in turn guarantees that, if work->data
+ * points to pwq which is associated with a locked pool, the work
+ * item is currently queued on that pool.
+ */
+ pwq = get_work_pwq(work);
+ if (pwq && pwq->pool == pool) {
+ debug_work_deactivate(work);
+
+ /*
+ * A delayed work item cannot be grabbed directly because
+ * it might have linked NO_COLOR work items which, if left
+ * on the delayed_list, will confuse pwq->nr_active
+ * management later on and cause stall. Make sure the work
+ * item is activated before grabbing.
+ */
+ if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
+ pwq_activate_delayed_work(work);
+
+ list_del_init(&work->entry);
+ pwq_dec_nr_in_flight(pwq, get_work_color(work));
+
+ /* work->data points to pwq iff queued, point to pool */
+ set_work_pool_and_keep_pending(work, pool->id);
+
+ spin_unlock(&pool->lock);
+ rcu_read_unlock();
+ return 1;
+ }
+ spin_unlock(&pool->lock);
+fail:
+ rcu_read_unlock();
+ local_unlock_irqrestore(pendingb_lock, *flags);
+ if (work_is_canceling(work))
+ return -ENOENT;
+ cpu_chill();
+ return -EAGAIN;
+}
+
+/**
+ * insert_work - insert a work into a pool
+ * @pwq: pwq @work belongs to
+ * @work: work to insert
+ * @head: insertion point
+ * @extra_flags: extra WORK_STRUCT_* flags to set
+ *
+ * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
+ * work_struct flags.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ */
+static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
+ struct list_head *head, unsigned int extra_flags)
+{
+ struct worker_pool *pool = pwq->pool;
+
+ /* we own @work, set data and link */
+ set_work_pwq(work, pwq, extra_flags);
+ list_add_tail(&work->entry, head);
+ get_pwq(pwq);
+
+ /*
+ * Ensure either wq_worker_sleeping() sees the above
+ * list_add_tail() or we see zero nr_running to avoid workers lying
+ * around lazily while there are works to be processed.
+ */
+ smp_mb();
+
+ if (__need_more_worker(pool))
+ wake_up_worker(pool);
+}
+
+/*
+ * Test whether @work is being queued from another work executing on the
+ * same workqueue.
+ */
+static bool is_chained_work(struct workqueue_struct *wq)
+{
+ struct worker *worker;
+
+ worker = current_wq_worker();
+ /*
+ * Return %true iff I'm a worker execuing a work item on @wq. If
+ * I'm @worker, it's safe to dereference it without locking.
+ */
+ return worker && worker->current_pwq->wq == wq;
+}
+
+static void __queue_work(int cpu, struct workqueue_struct *wq,
+ struct work_struct *work)
+{
+ struct pool_workqueue *pwq;
+ struct worker_pool *last_pool;
+ struct list_head *worklist;
+ unsigned int work_flags;
+ unsigned int req_cpu = cpu;
+
+ /*
+ * While a work item is PENDING && off queue, a task trying to
+ * steal the PENDING will busy-loop waiting for it to either get
+ * queued or lose PENDING. Grabbing PENDING and queueing should
+ * happen with IRQ disabled.
+ */
+ WARN_ON_ONCE_NONRT(!irqs_disabled());
+
+ debug_work_activate(work);
+
+ /* if draining, only works from the same workqueue are allowed */
+ if (unlikely(wq->flags & __WQ_DRAINING) &&
+ WARN_ON_ONCE(!is_chained_work(wq)))
+ return;
+
+ rcu_read_lock();
+retry:
+ if (req_cpu == WORK_CPU_UNBOUND)
+ cpu = raw_smp_processor_id();
+
+ /* pwq which will be used unless @work is executing elsewhere */
+ if (!(wq->flags & WQ_UNBOUND))
+ pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
+ else
+ pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
+
+ /*
+ * If @work was previously on a different pool, it might still be
+ * running there, in which case the work needs to be queued on that
+ * pool to guarantee non-reentrancy.
+ */
+ last_pool = get_work_pool(work);
+ if (last_pool && last_pool != pwq->pool) {
+ struct worker *worker;
+
+ spin_lock(&last_pool->lock);
+
+ worker = find_worker_executing_work(last_pool, work);
+
+ if (worker && worker->current_pwq->wq == wq) {
+ pwq = worker->current_pwq;
+ } else {
+ /* meh... not running there, queue here */
+ spin_unlock(&last_pool->lock);
+ spin_lock(&pwq->pool->lock);
+ }
+ } else {
+ spin_lock(&pwq->pool->lock);
+ }
+
+ /*
+ * pwq is determined and locked. For unbound pools, we could have
+ * raced with pwq release and it could already be dead. If its
+ * refcnt is zero, repeat pwq selection. Note that pwqs never die
+ * without another pwq replacing it in the numa_pwq_tbl or while
+ * work items are executing on it, so the retrying is guaranteed to
+ * make forward-progress.
+ */
+ if (unlikely(!pwq->refcnt)) {
+ if (wq->flags & WQ_UNBOUND) {
+ spin_unlock(&pwq->pool->lock);
+ cpu_relax();
+ goto retry;
+ }
+ /* oops */
+ WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
+ wq->name, cpu);
+ }
+
+ /* pwq determined, queue */
+ trace_workqueue_queue_work(req_cpu, pwq, work);
+
+ if (WARN_ON(!list_empty(&work->entry)))
+ goto out;
+
+ pwq->nr_in_flight[pwq->work_color]++;
+ work_flags = work_color_to_flags(pwq->work_color);
+
+ if (likely(pwq->nr_active < pwq->max_active)) {
+ trace_workqueue_activate_work(work);
+ pwq->nr_active++;
+ worklist = &pwq->pool->worklist;
+ } else {
+ work_flags |= WORK_STRUCT_DELAYED;
+ worklist = &pwq->delayed_works;
+ }
+
+ insert_work(pwq, work, worklist, work_flags);
+
+out:
+ spin_unlock(&pwq->pool->lock);
+ rcu_read_unlock();
+}
+
+/**
+ * queue_work_on - queue work on specific cpu
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @work: work to queue
+ *
+ * We queue the work to a specific CPU, the caller must ensure it
+ * can't go away.
+ *
+ * Return: %false if @work was already on a queue, %true otherwise.
+ */
+bool queue_work_on(int cpu, struct workqueue_struct *wq,
+ struct work_struct *work)
+{
+ bool ret = false;
+ unsigned long flags;
+
+ local_lock_irqsave(pendingb_lock,flags);
+
+ if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+ __queue_work(cpu, wq, work);
+ ret = true;
+ }
+
+ local_unlock_irqrestore(pendingb_lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(queue_work_on);
+
+void delayed_work_timer_fn(unsigned long __data)
+{
+ struct delayed_work *dwork = (struct delayed_work *)__data;
+
+ /* should have been called from irqsafe timer with irq already off */
+ __queue_work(dwork->cpu, dwork->wq, &dwork->work);
+}
+EXPORT_SYMBOL(delayed_work_timer_fn);
+
+static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay)
+{
+ struct timer_list *timer = &dwork->timer;
+ struct work_struct *work = &dwork->work;
+
+ WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
+ timer->data != (unsigned long)dwork);
+ WARN_ON_ONCE(timer_pending(timer));
+ WARN_ON_ONCE(!list_empty(&work->entry));
+
+ /*
+ * If @delay is 0, queue @dwork->work immediately. This is for
+ * both optimization and correctness. The earliest @timer can
+ * expire is on the closest next tick and delayed_work users depend
+ * on that there's no such delay when @delay is 0.
+ */
+ if (!delay) {
+ __queue_work(cpu, wq, &dwork->work);
+ return;
+ }
+
+ timer_stats_timer_set_start_info(&dwork->timer);
+
+ dwork->wq = wq;
+ dwork->cpu = cpu;
+ timer->expires = jiffies + delay;
+
+ if (unlikely(cpu != WORK_CPU_UNBOUND))
+ add_timer_on(timer, cpu);
+ else
+ add_timer(timer);
+}
+
+/**
+ * queue_delayed_work_on - queue work on specific CPU after delay
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @dwork: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * Return: %false if @work was already on a queue, %true otherwise. If
+ * @delay is zero and @dwork is idle, it will be scheduled for immediate
+ * execution.
+ */
+bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay)
+{
+ struct work_struct *work = &dwork->work;
+ bool ret = false;
+ unsigned long flags;
+
+ /* read the comment in __queue_work() */
+ local_lock_irqsave(pendingb_lock, flags);
+
+ if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+ __queue_delayed_work(cpu, wq, dwork, delay);
+ ret = true;
+ }
+
+ local_unlock_irqrestore(pendingb_lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(queue_delayed_work_on);
+
+/**
+ * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @dwork: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
+ * modify @dwork's timer so that it expires after @delay. If @delay is
+ * zero, @work is guaranteed to be scheduled immediately regardless of its
+ * current state.
+ *
+ * Return: %false if @dwork was idle and queued, %true if @dwork was
+ * pending and its timer was modified.
+ *
+ * This function is safe to call from any context including IRQ handler.
+ * See try_to_grab_pending() for details.
+ */
+bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay)
+{
+ unsigned long flags;
+ int ret;
+
+ do {
+ ret = try_to_grab_pending(&dwork->work, true, &flags);
+ } while (unlikely(ret == -EAGAIN));
+
+ if (likely(ret >= 0)) {
+ __queue_delayed_work(cpu, wq, dwork, delay);
+ local_unlock_irqrestore(pendingb_lock, flags);
+ }
+
+ /* -ENOENT from try_to_grab_pending() becomes %true */
+ return ret;
+}
+EXPORT_SYMBOL_GPL(mod_delayed_work_on);
+
+/**
+ * worker_enter_idle - enter idle state
+ * @worker: worker which is entering idle state
+ *
+ * @worker is entering idle state. Update stats and idle timer if
+ * necessary.
+ *
+ * LOCKING:
+ * spin_lock_irq(pool->lock).
+ */
+static void worker_enter_idle(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
+ WARN_ON_ONCE(!list_empty(&worker->entry) &&
+ (worker->hentry.next || worker->hentry.pprev)))
+ return;
+
+ /* can't use worker_set_flags(), also called from create_worker() */
+ worker->flags |= WORKER_IDLE;
+ pool->nr_idle++;
+ worker->last_active = jiffies;
+
+ /* idle_list is LIFO */
+ rt_lock_idle_list(pool);
+ list_add(&worker->entry, &pool->idle_list);
+ rt_unlock_idle_list(pool);
+
+ if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
+ mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
+
+ /*
+ * Sanity check nr_running. Because wq_unbind_fn() releases
+ * pool->lock between setting %WORKER_UNBOUND and zapping
+ * nr_running, the warning may trigger spuriously. Check iff
+ * unbind is not in progress.
+ */
+ WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
+ pool->nr_workers == pool->nr_idle &&
+ atomic_read(&pool->nr_running));
+}
+
+/**
+ * worker_leave_idle - leave idle state
+ * @worker: worker which is leaving idle state
+ *
+ * @worker is leaving idle state. Update stats.
+ *
+ * LOCKING:
+ * spin_lock_irq(pool->lock).
+ */
+static void worker_leave_idle(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
+ return;
+ worker_clr_flags(worker, WORKER_IDLE);
+ pool->nr_idle--;
+ rt_lock_idle_list(pool);
+ list_del_init(&worker->entry);
+ rt_unlock_idle_list(pool);
+}
+
+static struct worker *alloc_worker(int node)
+{
+ struct worker *worker;
+
+ worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node);
+ if (worker) {
+ INIT_LIST_HEAD(&worker->entry);
+ INIT_LIST_HEAD(&worker->scheduled);
+ INIT_LIST_HEAD(&worker->node);
+ /* on creation a worker is in !idle && prep state */
+ worker->flags = WORKER_PREP;
+ }
+ return worker;
+}
+
+/**
+ * worker_attach_to_pool() - attach a worker to a pool
+ * @worker: worker to be attached
+ * @pool: the target pool
+ *
+ * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
+ * cpu-binding of @worker are kept coordinated with the pool across
+ * cpu-[un]hotplugs.
+ */
+static void worker_attach_to_pool(struct worker *worker,
+ struct worker_pool *pool)
+{
+ mutex_lock(&pool->attach_mutex);
+
+ /*
+ * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
+ * online CPUs. It'll be re-applied when any of the CPUs come up.
+ */
+ set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
+
+ /*
+ * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
+ * stable across this function. See the comments above the
+ * flag definition for details.
+ */
+ if (pool->flags & POOL_DISASSOCIATED)
+ worker->flags |= WORKER_UNBOUND;
+
+ list_add_tail(&worker->node, &pool->workers);
+
+ mutex_unlock(&pool->attach_mutex);
+}
+
+/**
+ * worker_detach_from_pool() - detach a worker from its pool
+ * @worker: worker which is attached to its pool
+ * @pool: the pool @worker is attached to
+ *
+ * Undo the attaching which had been done in worker_attach_to_pool(). The
+ * caller worker shouldn't access to the pool after detached except it has
+ * other reference to the pool.
+ */
+static void worker_detach_from_pool(struct worker *worker,
+ struct worker_pool *pool)
+{
+ struct completion *detach_completion = NULL;
+
+ mutex_lock(&pool->attach_mutex);
+ list_del(&worker->node);
+ if (list_empty(&pool->workers))
+ detach_completion = pool->detach_completion;
+ mutex_unlock(&pool->attach_mutex);
+
+ /* clear leftover flags without pool->lock after it is detached */
+ worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND);
+
+ if (detach_completion)
+ complete(detach_completion);
+}
+
+/**
+ * create_worker - create a new workqueue worker
+ * @pool: pool the new worker will belong to
+ *
+ * Create and start a new worker which is attached to @pool.
+ *
+ * CONTEXT:
+ * Might sleep. Does GFP_KERNEL allocations.
+ *
+ * Return:
+ * Pointer to the newly created worker.
+ */
+static struct worker *create_worker(struct worker_pool *pool)
+{
+ struct worker *worker = NULL;
+ int id = -1;
+ char id_buf[16];
+
+ /* ID is needed to determine kthread name */
+ id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
+ if (id < 0)
+ goto fail;
+
+ worker = alloc_worker(pool->node);
+ if (!worker)
+ goto fail;
+
+ worker->pool = pool;
+ worker->id = id;
+
+ if (pool->cpu >= 0)
+ snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
+ pool->attrs->nice < 0 ? "H" : "");
+ else
+ snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
+
+ worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
+ "kworker/%s", id_buf);
+ if (IS_ERR(worker->task))
+ goto fail;
+
+ set_user_nice(worker->task, pool->attrs->nice);
+
+ /* prevent userland from meddling with cpumask of workqueue workers */
+ worker->task->flags |= PF_NO_SETAFFINITY;
+
+ /* successful, attach the worker to the pool */
+ worker_attach_to_pool(worker, pool);
+
+ /* start the newly created worker */
+ spin_lock_irq(&pool->lock);
+ worker->pool->nr_workers++;
+ worker_enter_idle(worker);
+ wake_up_process(worker->task);
+ spin_unlock_irq(&pool->lock);
+
+ return worker;
+
+fail:
+ if (id >= 0)
+ ida_simple_remove(&pool->worker_ida, id);
+ kfree(worker);
+ return NULL;
+}
+
+/**
+ * destroy_worker - destroy a workqueue worker
+ * @worker: worker to be destroyed
+ *
+ * Destroy @worker and adjust @pool stats accordingly. The worker should
+ * be idle.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ */
+static void destroy_worker(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ lockdep_assert_held(&pool->lock);
+
+ /* sanity check frenzy */
+ if (WARN_ON(worker->current_work) ||
+ WARN_ON(!list_empty(&worker->scheduled)) ||
+ WARN_ON(!(worker->flags & WORKER_IDLE)))
+ return;
+
+ pool->nr_workers--;
+ pool->nr_idle--;
+
+ rt_lock_idle_list(pool);
+ list_del_init(&worker->entry);
+ rt_unlock_idle_list(pool);
+ worker->flags |= WORKER_DIE;
+ wake_up_process(worker->task);
+}
+
+static void idle_worker_timeout(unsigned long __pool)
+{
+ struct worker_pool *pool = (void *)__pool;
+
+ spin_lock_irq(&pool->lock);
+
+ while (too_many_workers(pool)) {
+ struct worker *worker;
+ unsigned long expires;
+
+ /* idle_list is kept in LIFO order, check the last one */
+ worker = list_entry(pool->idle_list.prev, struct worker, entry);
+ expires = worker->last_active + IDLE_WORKER_TIMEOUT;
+
+ if (time_before(jiffies, expires)) {
+ mod_timer(&pool->idle_timer, expires);
+ break;
+ }
+
+ destroy_worker(worker);
+ }
+
+ spin_unlock_irq(&pool->lock);
+}
+
+static void send_mayday(struct work_struct *work)
+{
+ struct pool_workqueue *pwq = get_work_pwq(work);
+ struct workqueue_struct *wq = pwq->wq;
+
+ lockdep_assert_held(&wq_mayday_lock);
+
+ if (!wq->rescuer)
+ return;
+
+ /* mayday mayday mayday */
+ if (list_empty(&pwq->mayday_node)) {
+ /*
+ * If @pwq is for an unbound wq, its base ref may be put at
+ * any time due to an attribute change. Pin @pwq until the
+ * rescuer is done with it.
+ */
+ get_pwq(pwq);
+ list_add_tail(&pwq->mayday_node, &wq->maydays);
+ wake_up_process(wq->rescuer->task);
+ }
+}
+
+static void pool_mayday_timeout(unsigned long __pool)
+{
+ struct worker_pool *pool = (void *)__pool;
+ struct work_struct *work;
+
+ spin_lock_irq(&pool->lock);
+ spin_lock(&wq_mayday_lock); /* for wq->maydays */
+
+ if (need_to_create_worker(pool)) {
+ /*
+ * We've been trying to create a new worker but
+ * haven't been successful. We might be hitting an
+ * allocation deadlock. Send distress signals to
+ * rescuers.
+ */
+ list_for_each_entry(work, &pool->worklist, entry)
+ send_mayday(work);
+ }
+
+ spin_unlock(&wq_mayday_lock);
+ spin_unlock_irq(&pool->lock);
+
+ mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
+}
+
+/**
+ * maybe_create_worker - create a new worker if necessary
+ * @pool: pool to create a new worker for
+ *
+ * Create a new worker for @pool if necessary. @pool is guaranteed to
+ * have at least one idle worker on return from this function. If
+ * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
+ * sent to all rescuers with works scheduled on @pool to resolve
+ * possible allocation deadlock.
+ *
+ * On return, need_to_create_worker() is guaranteed to be %false and
+ * may_start_working() %true.
+ *
+ * LOCKING:
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * multiple times. Does GFP_KERNEL allocations. Called only from
+ * manager.
+ */
+static void maybe_create_worker(struct worker_pool *pool)
+__releases(&pool->lock)
+__acquires(&pool->lock)
+{
+restart:
+ spin_unlock_irq(&pool->lock);
+
+ /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
+ mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
+
+ while (true) {
+ if (create_worker(pool) || !need_to_create_worker(pool))
+ break;
+
+ schedule_timeout_interruptible(CREATE_COOLDOWN);
+
+ if (!need_to_create_worker(pool))
+ break;
+ }
+
+ del_timer_sync(&pool->mayday_timer);
+ spin_lock_irq(&pool->lock);
+ /*
+ * This is necessary even after a new worker was just successfully
+ * created as @pool->lock was dropped and the new worker might have
+ * already become busy.
+ */
+ if (need_to_create_worker(pool))
+ goto restart;
+}
+
+/**
+ * manage_workers - manage worker pool
+ * @worker: self
+ *
+ * Assume the manager role and manage the worker pool @worker belongs
+ * to. At any given time, there can be only zero or one manager per
+ * pool. The exclusion is handled automatically by this function.
+ *
+ * The caller can safely start processing works on false return. On
+ * true return, it's guaranteed that need_to_create_worker() is false
+ * and may_start_working() is true.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * multiple times. Does GFP_KERNEL allocations.
+ *
+ * Return:
+ * %false if the pool doesn't need management and the caller can safely
+ * start processing works, %true if management function was performed and
+ * the conditions that the caller verified before calling the function may
+ * no longer be true.
+ */
+static bool manage_workers(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ /*
+ * Anyone who successfully grabs manager_arb wins the arbitration
+ * and becomes the manager. mutex_trylock() on pool->manager_arb
+ * failure while holding pool->lock reliably indicates that someone
+ * else is managing the pool and the worker which failed trylock
+ * can proceed to executing work items. This means that anyone
+ * grabbing manager_arb is responsible for actually performing
+ * manager duties. If manager_arb is grabbed and released without
+ * actual management, the pool may stall indefinitely.
+ */
+ if (!mutex_trylock(&pool->manager_arb))
+ return false;
+ pool->manager = worker;
+
+ maybe_create_worker(pool);
+
+ pool->manager = NULL;
+ mutex_unlock(&pool->manager_arb);
+ return true;
+}
+
+/**
+ * process_one_work - process single work
+ * @worker: self
+ * @work: work to process
+ *
+ * Process @work. This function contains all the logics necessary to
+ * process a single work including synchronization against and
+ * interaction with other workers on the same cpu, queueing and
+ * flushing. As long as context requirement is met, any worker can
+ * call this function to process a work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock) which is released and regrabbed.
+ */
+static void process_one_work(struct worker *worker, struct work_struct *work)
+__releases(&pool->lock)
+__acquires(&pool->lock)
+{
+ struct pool_workqueue *pwq = get_work_pwq(work);
+ struct worker_pool *pool = worker->pool;
+ bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
+ int work_color;
+ struct worker *collision;
+#ifdef CONFIG_LOCKDEP
+ /*
+ * It is permissible to free the struct work_struct from
+ * inside the function that is called from it, this we need to
+ * take into account for lockdep too. To avoid bogus "held
+ * lock freed" warnings as well as problems when looking into
+ * work->lockdep_map, make a copy and use that here.
+ */
+ struct lockdep_map lockdep_map;
+
+ lockdep_copy_map(&lockdep_map, &work->lockdep_map);
+#endif
+ /* ensure we're on the correct CPU */
+ WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
+ raw_smp_processor_id() != pool->cpu);
+
+ /*
+ * A single work shouldn't be executed concurrently by
+ * multiple workers on a single cpu. Check whether anyone is
+ * already processing the work. If so, defer the work to the
+ * currently executing one.
+ */
+ collision = find_worker_executing_work(pool, work);
+ if (unlikely(collision)) {
+ move_linked_works(work, &collision->scheduled, NULL);
+ return;
+ }
+
+ /* claim and dequeue */
+ debug_work_deactivate(work);
+ hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
+ worker->current_work = work;
+ worker->current_func = work->func;
+ worker->current_pwq = pwq;
+ work_color = get_work_color(work);
+
+ list_del_init(&work->entry);
+
+ /*
+ * CPU intensive works don't participate in concurrency management.
+ * They're the scheduler's responsibility. This takes @worker out
+ * of concurrency management and the next code block will chain
+ * execution of the pending work items.
+ */
+ if (unlikely(cpu_intensive))
+ worker_set_flags(worker, WORKER_CPU_INTENSIVE);
+
+ /*
+ * Wake up another worker if necessary. The condition is always
+ * false for normal per-cpu workers since nr_running would always
+ * be >= 1 at this point. This is used to chain execution of the
+ * pending work items for WORKER_NOT_RUNNING workers such as the
+ * UNBOUND and CPU_INTENSIVE ones.
+ */
+ if (need_more_worker(pool))
+ wake_up_worker(pool);
+
+ /*
+ * Record the last pool and clear PENDING which should be the last
+ * update to @work. Also, do this inside @pool->lock so that
+ * PENDING and queued state changes happen together while IRQ is
+ * disabled.
+ */
+ set_work_pool_and_clear_pending(work, pool->id);
+
+ spin_unlock_irq(&pool->lock);
+
+ lock_map_acquire_read(&pwq->wq->lockdep_map);
+ lock_map_acquire(&lockdep_map);
+ trace_workqueue_execute_start(work);
+ worker->current_func(work);
+ /*
+ * While we must be careful to not use "work" after this, the trace
+ * point will only record its address.
+ */
+ trace_workqueue_execute_end(work);
+ lock_map_release(&lockdep_map);
+ lock_map_release(&pwq->wq->lockdep_map);
+
+ if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
+ pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
+ " last function: %pf\n",
+ current->comm, preempt_count(), task_pid_nr(current),
+ worker->current_func);
+ debug_show_held_locks(current);
+ dump_stack();
+ }
+
+ /*
+ * The following prevents a kworker from hogging CPU on !PREEMPT
+ * kernels, where a requeueing work item waiting for something to
+ * happen could deadlock with stop_machine as such work item could
+ * indefinitely requeue itself while all other CPUs are trapped in
+ * stop_machine. At the same time, report a quiescent RCU state so
+ * the same condition doesn't freeze RCU.
+ */
+ cond_resched_rcu_qs();
+
+ spin_lock_irq(&pool->lock);
+
+ /* clear cpu intensive status */
+ if (unlikely(cpu_intensive))
+ worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
+
+ /* we're done with it, release */
+ hash_del(&worker->hentry);
+ worker->current_work = NULL;
+ worker->current_func = NULL;
+ worker->current_pwq = NULL;
+ worker->desc_valid = false;
+ pwq_dec_nr_in_flight(pwq, work_color);
+}
+
+/**
+ * process_scheduled_works - process scheduled works
+ * @worker: self
+ *
+ * Process all scheduled works. Please note that the scheduled list
+ * may change while processing a work, so this function repeatedly
+ * fetches a work from the top and executes it.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * multiple times.
+ */
+static void process_scheduled_works(struct worker *worker)
+{
+ while (!list_empty(&worker->scheduled)) {
+ struct work_struct *work = list_first_entry(&worker->scheduled,
+ struct work_struct, entry);
+ process_one_work(worker, work);
+ }
+}
+
+/**
+ * worker_thread - the worker thread function
+ * @__worker: self
+ *
+ * The worker thread function. All workers belong to a worker_pool -
+ * either a per-cpu one or dynamic unbound one. These workers process all
+ * work items regardless of their specific target workqueue. The only
+ * exception is work items which belong to workqueues with a rescuer which
+ * will be explained in rescuer_thread().
+ *
+ * Return: 0
+ */
+static int worker_thread(void *__worker)
+{
+ struct worker *worker = __worker;
+ struct worker_pool *pool = worker->pool;
+
+ /* tell the scheduler that this is a workqueue worker */
+ worker->task->flags |= PF_WQ_WORKER;
+woke_up:
+ spin_lock_irq(&pool->lock);
+
+ /* am I supposed to die? */
+ if (unlikely(worker->flags & WORKER_DIE)) {
+ spin_unlock_irq(&pool->lock);
+ WARN_ON_ONCE(!list_empty(&worker->entry));
+ worker->task->flags &= ~PF_WQ_WORKER;
+
+ set_task_comm(worker->task, "kworker/dying");
+ ida_simple_remove(&pool->worker_ida, worker->id);
+ worker_detach_from_pool(worker, pool);
+ kfree(worker);
+ return 0;
+ }
+
+ worker_leave_idle(worker);
+recheck:
+ /* no more worker necessary? */
+ if (!need_more_worker(pool))
+ goto sleep;
+
+ /* do we need to manage? */
+ if (unlikely(!may_start_working(pool)) && manage_workers(worker))
+ goto recheck;
+
+ /*
+ * ->scheduled list can only be filled while a worker is
+ * preparing to process a work or actually processing it.
+ * Make sure nobody diddled with it while I was sleeping.
+ */
+ WARN_ON_ONCE(!list_empty(&worker->scheduled));
+
+ /*
+ * Finish PREP stage. We're guaranteed to have at least one idle
+ * worker or that someone else has already assumed the manager
+ * role. This is where @worker starts participating in concurrency
+ * management if applicable and concurrency management is restored
+ * after being rebound. See rebind_workers() for details.
+ */
+ worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
+
+ do {
+ struct work_struct *work =
+ list_first_entry(&pool->worklist,
+ struct work_struct, entry);
+
+ if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
+ /* optimization path, not strictly necessary */
+ process_one_work(worker, work);
+ if (unlikely(!list_empty(&worker->scheduled)))
+ process_scheduled_works(worker);
+ } else {
+ move_linked_works(work, &worker->scheduled, NULL);
+ process_scheduled_works(worker);
+ }
+ } while (keep_working(pool));
+
+ worker_set_flags(worker, WORKER_PREP);
+sleep:
+ /*
+ * pool->lock is held and there's no work to process and no need to
+ * manage, sleep. Workers are woken up only while holding
+ * pool->lock or from local cpu, so setting the current state
+ * before releasing pool->lock is enough to prevent losing any
+ * event.
+ */
+ worker_enter_idle(worker);
+ __set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&pool->lock);
+ schedule();
+ goto woke_up;
+}
+
+/**
+ * rescuer_thread - the rescuer thread function
+ * @__rescuer: self
+ *
+ * Workqueue rescuer thread function. There's one rescuer for each
+ * workqueue which has WQ_MEM_RECLAIM set.
+ *
+ * Regular work processing on a pool may block trying to create a new
+ * worker which uses GFP_KERNEL allocation which has slight chance of
+ * developing into deadlock if some works currently on the same queue
+ * need to be processed to satisfy the GFP_KERNEL allocation. This is
+ * the problem rescuer solves.
+ *
+ * When such condition is possible, the pool summons rescuers of all
+ * workqueues which have works queued on the pool and let them process
+ * those works so that forward progress can be guaranteed.
+ *
+ * This should happen rarely.
+ *
+ * Return: 0
+ */
+static int rescuer_thread(void *__rescuer)
+{
+ struct worker *rescuer = __rescuer;
+ struct workqueue_struct *wq = rescuer->rescue_wq;
+ struct list_head *scheduled = &rescuer->scheduled;
+ bool should_stop;
+
+ set_user_nice(current, RESCUER_NICE_LEVEL);
+
+ /*
+ * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
+ * doesn't participate in concurrency management.
+ */
+ rescuer->task->flags |= PF_WQ_WORKER;
+repeat:
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ /*
+ * By the time the rescuer is requested to stop, the workqueue
+ * shouldn't have any work pending, but @wq->maydays may still have
+ * pwq(s) queued. This can happen by non-rescuer workers consuming
+ * all the work items before the rescuer got to them. Go through
+ * @wq->maydays processing before acting on should_stop so that the
+ * list is always empty on exit.
+ */
+ should_stop = kthread_should_stop();
+
+ /* see whether any pwq is asking for help */
+ spin_lock_irq(&wq_mayday_lock);
+
+ while (!list_empty(&wq->maydays)) {
+ struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
+ struct pool_workqueue, mayday_node);
+ struct worker_pool *pool = pwq->pool;
+ struct work_struct *work, *n;
+
+ __set_current_state(TASK_RUNNING);
+ list_del_init(&pwq->mayday_node);
+
+ spin_unlock_irq(&wq_mayday_lock);
+
+ worker_attach_to_pool(rescuer, pool);
+
+ spin_lock_irq(&pool->lock);
+ rescuer->pool = pool;
+
+ /*
+ * Slurp in all works issued via this workqueue and
+ * process'em.
+ */
+ WARN_ON_ONCE(!list_empty(scheduled));
+ list_for_each_entry_safe(work, n, &pool->worklist, entry)
+ if (get_work_pwq(work) == pwq)
+ move_linked_works(work, scheduled, &n);
+
+ if (!list_empty(scheduled)) {
+ process_scheduled_works(rescuer);
+
+ /*
+ * The above execution of rescued work items could
+ * have created more to rescue through
+ * pwq_activate_first_delayed() or chained
+ * queueing. Let's put @pwq back on mayday list so
+ * that such back-to-back work items, which may be
+ * being used to relieve memory pressure, don't
+ * incur MAYDAY_INTERVAL delay inbetween.
+ */
+ if (need_to_create_worker(pool)) {
+ spin_lock(&wq_mayday_lock);
+ get_pwq(pwq);
+ list_move_tail(&pwq->mayday_node, &wq->maydays);
+ spin_unlock(&wq_mayday_lock);
+ }
+ }
+
+ /*
+ * Put the reference grabbed by send_mayday(). @pool won't
+ * go away while we're still attached to it.
+ */
+ put_pwq(pwq);
+
+ /*
+ * Leave this pool. If need_more_worker() is %true, notify a
+ * regular worker; otherwise, we end up with 0 concurrency
+ * and stalling the execution.
+ */
+ if (need_more_worker(pool))
+ wake_up_worker(pool);
+
+ rescuer->pool = NULL;
+ spin_unlock_irq(&pool->lock);
+
+ worker_detach_from_pool(rescuer, pool);
+
+ spin_lock_irq(&wq_mayday_lock);
+ }
+
+ spin_unlock_irq(&wq_mayday_lock);
+
+ if (should_stop) {
+ __set_current_state(TASK_RUNNING);
+ rescuer->task->flags &= ~PF_WQ_WORKER;
+ return 0;
+ }
+
+ /* rescuers should never participate in concurrency management */
+ WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
+ schedule();
+ goto repeat;
+}
+
+struct wq_barrier {
+ struct work_struct work;
+ struct completion done;
+ struct task_struct *task; /* purely informational */
+};
+
+static void wq_barrier_func(struct work_struct *work)
+{
+ struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
+ complete(&barr->done);
+}
+
+/**
+ * insert_wq_barrier - insert a barrier work
+ * @pwq: pwq to insert barrier into
+ * @barr: wq_barrier to insert
+ * @target: target work to attach @barr to
+ * @worker: worker currently executing @target, NULL if @target is not executing
+ *
+ * @barr is linked to @target such that @barr is completed only after
+ * @target finishes execution. Please note that the ordering
+ * guarantee is observed only with respect to @target and on the local
+ * cpu.
+ *
+ * Currently, a queued barrier can't be canceled. This is because
+ * try_to_grab_pending() can't determine whether the work to be
+ * grabbed is at the head of the queue and thus can't clear LINKED
+ * flag of the previous work while there must be a valid next work
+ * after a work with LINKED flag set.
+ *
+ * Note that when @worker is non-NULL, @target may be modified
+ * underneath us, so we can't reliably determine pwq from @target.
+ *
+ * CONTEXT:
+ * spin_lock_irq(pool->lock).
+ */
+static void insert_wq_barrier(struct pool_workqueue *pwq,
+ struct wq_barrier *barr,
+ struct work_struct *target, struct worker *worker)
+{
+ struct list_head *head;
+ unsigned int linked = 0;
+
+ /*
+ * debugobject calls are safe here even with pool->lock locked
+ * as we know for sure that this will not trigger any of the
+ * checks and call back into the fixup functions where we
+ * might deadlock.
+ */
+ INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
+ __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
+ init_completion(&barr->done);
+ barr->task = current;
+
+ /*
+ * If @target is currently being executed, schedule the
+ * barrier to the worker; otherwise, put it after @target.
+ */
+ if (worker)
+ head = worker->scheduled.next;
+ else {
+ unsigned long *bits = work_data_bits(target);
+
+ head = target->entry.next;
+ /* there can already be other linked works, inherit and set */
+ linked = *bits & WORK_STRUCT_LINKED;
+ __set_bit(WORK_STRUCT_LINKED_BIT, bits);
+ }
+
+ debug_work_activate(&barr->work);
+ insert_work(pwq, &barr->work, head,
+ work_color_to_flags(WORK_NO_COLOR) | linked);
+}
+
+/**
+ * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
+ * @wq: workqueue being flushed
+ * @flush_color: new flush color, < 0 for no-op
+ * @work_color: new work color, < 0 for no-op
+ *
+ * Prepare pwqs for workqueue flushing.
+ *
+ * If @flush_color is non-negative, flush_color on all pwqs should be
+ * -1. If no pwq has in-flight commands at the specified color, all
+ * pwq->flush_color's stay at -1 and %false is returned. If any pwq
+ * has in flight commands, its pwq->flush_color is set to
+ * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
+ * wakeup logic is armed and %true is returned.
+ *
+ * The caller should have initialized @wq->first_flusher prior to
+ * calling this function with non-negative @flush_color. If
+ * @flush_color is negative, no flush color update is done and %false
+ * is returned.
+ *
+ * If @work_color is non-negative, all pwqs should have the same
+ * work_color which is previous to @work_color and all will be
+ * advanced to @work_color.
+ *
+ * CONTEXT:
+ * mutex_lock(wq->mutex).
+ *
+ * Return:
+ * %true if @flush_color >= 0 and there's something to flush. %false
+ * otherwise.
+ */
+static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
+ int flush_color, int work_color)
+{
+ bool wait = false;
+ struct pool_workqueue *pwq;
+
+ if (flush_color >= 0) {
+ WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
+ atomic_set(&wq->nr_pwqs_to_flush, 1);
+ }
+
+ for_each_pwq(pwq, wq) {
+ struct worker_pool *pool = pwq->pool;
+
+ spin_lock_irq(&pool->lock);
+
+ if (flush_color >= 0) {
+ WARN_ON_ONCE(pwq->flush_color != -1);
+
+ if (pwq->nr_in_flight[flush_color]) {
+ pwq->flush_color = flush_color;
+ atomic_inc(&wq->nr_pwqs_to_flush);
+ wait = true;
+ }
+ }
+
+ if (work_color >= 0) {
+ WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
+ pwq->work_color = work_color;
+ }
+
+ spin_unlock_irq(&pool->lock);
+ }
+
+ if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
+ complete(&wq->first_flusher->done);
+
+ return wait;
+}
+
+/**
+ * flush_workqueue - ensure that any scheduled work has run to completion.
+ * @wq: workqueue to flush
+ *
+ * This function sleeps until all work items which were queued on entry
+ * have finished execution, but it is not livelocked by new incoming ones.
+ */
+void flush_workqueue(struct workqueue_struct *wq)
+{
+ struct wq_flusher this_flusher = {
+ .list = LIST_HEAD_INIT(this_flusher.list),
+ .flush_color = -1,
+ .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
+ };
+ int next_color;
+
+ lock_map_acquire(&wq->lockdep_map);
+ lock_map_release(&wq->lockdep_map);
+
+ mutex_lock(&wq->mutex);
+
+ /*
+ * Start-to-wait phase
+ */
+ next_color = work_next_color(wq->work_color);
+
+ if (next_color != wq->flush_color) {
+ /*
+ * Color space is not full. The current work_color
+ * becomes our flush_color and work_color is advanced
+ * by one.
+ */
+ WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
+ this_flusher.flush_color = wq->work_color;
+ wq->work_color = next_color;
+
+ if (!wq->first_flusher) {
+ /* no flush in progress, become the first flusher */
+ WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
+
+ wq->first_flusher = &this_flusher;
+
+ if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
+ wq->work_color)) {
+ /* nothing to flush, done */
+ wq->flush_color = next_color;
+ wq->first_flusher = NULL;
+ goto out_unlock;
+ }
+ } else {
+ /* wait in queue */
+ WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
+ list_add_tail(&this_flusher.list, &wq->flusher_queue);
+ flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
+ }
+ } else {
+ /*
+ * Oops, color space is full, wait on overflow queue.
+ * The next flush completion will assign us
+ * flush_color and transfer to flusher_queue.
+ */
+ list_add_tail(&this_flusher.list, &wq->flusher_overflow);
+ }
+
+ mutex_unlock(&wq->mutex);
+
+ wait_for_completion(&this_flusher.done);
+
+ /*
+ * Wake-up-and-cascade phase
+ *
+ * First flushers are responsible for cascading flushes and
+ * handling overflow. Non-first flushers can simply return.
+ */
+ if (wq->first_flusher != &this_flusher)
+ return;
+
+ mutex_lock(&wq->mutex);
+
+ /* we might have raced, check again with mutex held */
+ if (wq->first_flusher != &this_flusher)
+ goto out_unlock;
+
+ wq->first_flusher = NULL;
+
+ WARN_ON_ONCE(!list_empty(&this_flusher.list));
+ WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
+
+ while (true) {
+ struct wq_flusher *next, *tmp;
+
+ /* complete all the flushers sharing the current flush color */
+ list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
+ if (next->flush_color != wq->flush_color)
+ break;
+ list_del_init(&next->list);
+ complete(&next->done);
+ }
+
+ WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
+ wq->flush_color != work_next_color(wq->work_color));
+
+ /* this flush_color is finished, advance by one */
+ wq->flush_color = work_next_color(wq->flush_color);
+
+ /* one color has been freed, handle overflow queue */
+ if (!list_empty(&wq->flusher_overflow)) {
+ /*
+ * Assign the same color to all overflowed
+ * flushers, advance work_color and append to
+ * flusher_queue. This is the start-to-wait
+ * phase for these overflowed flushers.
+ */
+ list_for_each_entry(tmp, &wq->flusher_overflow, list)
+ tmp->flush_color = wq->work_color;
+
+ wq->work_color = work_next_color(wq->work_color);
+
+ list_splice_tail_init(&wq->flusher_overflow,
+ &wq->flusher_queue);
+ flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
+ }
+
+ if (list_empty(&wq->flusher_queue)) {
+ WARN_ON_ONCE(wq->flush_color != wq->work_color);
+ break;
+ }
+
+ /*
+ * Need to flush more colors. Make the next flusher
+ * the new first flusher and arm pwqs.
+ */
+ WARN_ON_ONCE(wq->flush_color == wq->work_color);
+ WARN_ON_ONCE(wq->flush_color != next->flush_color);
+
+ list_del_init(&next->list);
+ wq->first_flusher = next;
+
+ if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
+ break;
+
+ /*
+ * Meh... this color is already done, clear first
+ * flusher and repeat cascading.
+ */
+ wq->first_flusher = NULL;
+ }
+
+out_unlock:
+ mutex_unlock(&wq->mutex);
+}
+EXPORT_SYMBOL_GPL(flush_workqueue);
+
+/**
+ * drain_workqueue - drain a workqueue
+ * @wq: workqueue to drain
+ *
+ * Wait until the workqueue becomes empty. While draining is in progress,
+ * only chain queueing is allowed. IOW, only currently pending or running
+ * work items on @wq can queue further work items on it. @wq is flushed
+ * repeatedly until it becomes empty. The number of flushing is detemined
+ * by the depth of chaining and should be relatively short. Whine if it
+ * takes too long.
+ */
+void drain_workqueue(struct workqueue_struct *wq)
+{
+ unsigned int flush_cnt = 0;
+ struct pool_workqueue *pwq;
+
+ /*
+ * __queue_work() needs to test whether there are drainers, is much
+ * hotter than drain_workqueue() and already looks at @wq->flags.
+ * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
+ */
+ mutex_lock(&wq->mutex);
+ if (!wq->nr_drainers++)
+ wq->flags |= __WQ_DRAINING;
+ mutex_unlock(&wq->mutex);
+reflush:
+ flush_workqueue(wq);
+
+ mutex_lock(&wq->mutex);
+
+ for_each_pwq(pwq, wq) {
+ bool drained;
+
+ spin_lock_irq(&pwq->pool->lock);
+ drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
+ spin_unlock_irq(&pwq->pool->lock);
+
+ if (drained)
+ continue;
+
+ if (++flush_cnt == 10 ||
+ (flush_cnt % 100 == 0 && flush_cnt <= 1000))
+ pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
+ wq->name, flush_cnt);
+
+ mutex_unlock(&wq->mutex);
+ goto reflush;
+ }
+
+ if (!--wq->nr_drainers)
+ wq->flags &= ~__WQ_DRAINING;
+ mutex_unlock(&wq->mutex);
+}
+EXPORT_SYMBOL_GPL(drain_workqueue);
+
+static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
+{
+ struct worker *worker = NULL;
+ struct worker_pool *pool;
+ struct pool_workqueue *pwq;
+
+ might_sleep();
+
+ rcu_read_lock();
+ pool = get_work_pool(work);
+ if (!pool) {
+ rcu_read_unlock();
+ return false;
+ }
+
+ spin_lock_irq(&pool->lock);
+ /* see the comment in try_to_grab_pending() with the same code */
+ pwq = get_work_pwq(work);
+ if (pwq) {
+ if (unlikely(pwq->pool != pool))
+ goto already_gone;
+ } else {
+ worker = find_worker_executing_work(pool, work);
+ if (!worker)
+ goto already_gone;
+ pwq = worker->current_pwq;
+ }
+
+ insert_wq_barrier(pwq, barr, work, worker);
+ spin_unlock_irq(&pool->lock);
+
+ /*
+ * If @max_active is 1 or rescuer is in use, flushing another work
+ * item on the same workqueue may lead to deadlock. Make sure the
+ * flusher is not running on the same workqueue by verifying write
+ * access.
+ */
+ if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
+ lock_map_acquire(&pwq->wq->lockdep_map);
+ else
+ lock_map_acquire_read(&pwq->wq->lockdep_map);
+ lock_map_release(&pwq->wq->lockdep_map);
+ rcu_read_unlock();
+ return true;
+already_gone:
+ spin_unlock_irq(&pool->lock);
+ rcu_read_unlock();
+ return false;
+}
+
+/**
+ * flush_work - wait for a work to finish executing the last queueing instance
+ * @work: the work to flush
+ *
+ * Wait until @work has finished execution. @work is guaranteed to be idle
+ * on return if it hasn't been requeued since flush started.
+ *
+ * Return:
+ * %true if flush_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_work(struct work_struct *work)
+{
+ struct wq_barrier barr;
+
+ lock_map_acquire(&work->lockdep_map);
+ lock_map_release(&work->lockdep_map);
+
+ if (start_flush_work(work, &barr)) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ return true;
+ } else {
+ return false;
+ }
+}
+EXPORT_SYMBOL_GPL(flush_work);
+
+struct cwt_wait {
+ wait_queue_t wait;
+ struct work_struct *work;
+};
+
+static int cwt_wakefn(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+ struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait);
+
+ if (cwait->work != key)
+ return 0;
+ return autoremove_wake_function(wait, mode, sync, key);
+}
+
+static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
+{
+ static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq);
+ unsigned long flags;
+ int ret;
+
+ do {
+ ret = try_to_grab_pending(work, is_dwork, &flags);
+ /*
+ * If someone else is already canceling, wait for it to
+ * finish. flush_work() doesn't work for PREEMPT_NONE
+ * because we may get scheduled between @work's completion
+ * and the other canceling task resuming and clearing
+ * CANCELING - flush_work() will return false immediately
+ * as @work is no longer busy, try_to_grab_pending() will
+ * return -ENOENT as @work is still being canceled and the
+ * other canceling task won't be able to clear CANCELING as
+ * we're hogging the CPU.
+ *
+ * Let's wait for completion using a waitqueue. As this
+ * may lead to the thundering herd problem, use a custom
+ * wake function which matches @work along with exclusive
+ * wait and wakeup.
+ */
+ if (unlikely(ret == -ENOENT)) {
+ struct cwt_wait cwait;
+
+ init_wait(&cwait.wait);
+ cwait.wait.func = cwt_wakefn;
+ cwait.work = work;
+
+ prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait,
+ TASK_UNINTERRUPTIBLE);
+ if (work_is_canceling(work))
+ schedule();
+ finish_wait(&cancel_waitq, &cwait.wait);
+ }
+ } while (unlikely(ret < 0));
+
+ /* tell other tasks trying to grab @work to back off */
+ mark_work_canceling(work);
+ local_unlock_irqrestore(pendingb_lock, flags);
+
+ flush_work(work);
+ clear_work_data(work);
+
+ /*
+ * Paired with prepare_to_wait() above so that either
+ * waitqueue_active() is visible here or !work_is_canceling() is
+ * visible there.
+ */
+ smp_mb();
+ if (waitqueue_active(&cancel_waitq))
+ __wake_up(&cancel_waitq, TASK_NORMAL, 1, work);
+
+ return ret;
+}
+
+/**
+ * cancel_work_sync - cancel a work and wait for it to finish
+ * @work: the work to cancel
+ *
+ * Cancel @work and wait for its execution to finish. This function
+ * can be used even if the work re-queues itself or migrates to
+ * another workqueue. On return from this function, @work is
+ * guaranteed to be not pending or executing on any CPU.
+ *
+ * cancel_work_sync(&delayed_work->work) must not be used for
+ * delayed_work's. Use cancel_delayed_work_sync() instead.
+ *
+ * The caller must ensure that the workqueue on which @work was last
+ * queued can't be destroyed before this function returns.
+ *
+ * Return:
+ * %true if @work was pending, %false otherwise.
+ */
+bool cancel_work_sync(struct work_struct *work)
+{
+ return __cancel_work_timer(work, false);
+}
+EXPORT_SYMBOL_GPL(cancel_work_sync);
+
+/**
+ * flush_delayed_work - wait for a dwork to finish executing the last queueing
+ * @dwork: the delayed work to flush
+ *
+ * Delayed timer is cancelled and the pending work is queued for
+ * immediate execution. Like flush_work(), this function only
+ * considers the last queueing instance of @dwork.
+ *
+ * Return:
+ * %true if flush_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_delayed_work(struct delayed_work *dwork)
+{
+ local_lock_irq(pendingb_lock);
+ if (del_timer_sync(&dwork->timer))
+ __queue_work(dwork->cpu, dwork->wq, &dwork->work);
+ local_unlock_irq(pendingb_lock);
+ return flush_work(&dwork->work);
+}
+EXPORT_SYMBOL(flush_delayed_work);
+
+/**
+ * cancel_delayed_work - cancel a delayed work
+ * @dwork: delayed_work to cancel
+ *
+ * Kill off a pending delayed_work.
+ *
+ * Return: %true if @dwork was pending and canceled; %false if it wasn't
+ * pending.
+ *
+ * Note:
+ * The work callback function may still be running on return, unless
+ * it returns %true and the work doesn't re-arm itself. Explicitly flush or
+ * use cancel_delayed_work_sync() to wait on it.
+ *
+ * This function is safe to call from any context including IRQ handler.
+ */
+bool cancel_delayed_work(struct delayed_work *dwork)
+{
+ unsigned long flags;
+ int ret;
+
+ do {
+ ret = try_to_grab_pending(&dwork->work, true, &flags);
+ } while (unlikely(ret == -EAGAIN));
+
+ if (unlikely(ret < 0))
+ return false;
+
+ set_work_pool_and_clear_pending(&dwork->work,
+ get_work_pool_id(&dwork->work));
+ local_unlock_irqrestore(pendingb_lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(cancel_delayed_work);
+
+/**
+ * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
+ * @dwork: the delayed work cancel
+ *
+ * This is cancel_work_sync() for delayed works.
+ *
+ * Return:
+ * %true if @dwork was pending, %false otherwise.
+ */
+bool cancel_delayed_work_sync(struct delayed_work *dwork)
+{
+ return __cancel_work_timer(&dwork->work, true);
+}
+EXPORT_SYMBOL(cancel_delayed_work_sync);
+
+/**
+ * schedule_on_each_cpu - execute a function synchronously on each online CPU
+ * @func: the function to call
+ *
+ * schedule_on_each_cpu() executes @func on each online CPU using the
+ * system workqueue and blocks until all CPUs have completed.
+ * schedule_on_each_cpu() is very slow.
+ *
+ * Return:
+ * 0 on success, -errno on failure.
+ */
+int schedule_on_each_cpu(work_func_t func)
+{
+ int cpu;
+ struct work_struct __percpu *works;
+
+ works = alloc_percpu(struct work_struct);
+ if (!works)
+ return -ENOMEM;
+
+ get_online_cpus();
+
+ for_each_online_cpu(cpu) {
+ struct work_struct *work = per_cpu_ptr(works, cpu);
+
+ INIT_WORK(work, func);
+ schedule_work_on(cpu, work);
+ }
+
+ for_each_online_cpu(cpu)
+ flush_work(per_cpu_ptr(works, cpu));
+
+ put_online_cpus();
+ free_percpu(works);
+ return 0;
+}
+
+/**
+ * flush_scheduled_work - ensure that any scheduled work has run to completion.
+ *
+ * Forces execution of the kernel-global workqueue and blocks until its
+ * completion.
+ *
+ * Think twice before calling this function! It's very easy to get into
+ * trouble if you don't take great care. Either of the following situations
+ * will lead to deadlock:
+ *
+ * One of the work items currently on the workqueue needs to acquire
+ * a lock held by your code or its caller.
+ *
+ * Your code is running in the context of a work routine.
+ *
+ * They will be detected by lockdep when they occur, but the first might not
+ * occur very often. It depends on what work items are on the workqueue and
+ * what locks they need, which you have no control over.
+ *
+ * In most situations flushing the entire workqueue is overkill; you merely
+ * need to know that a particular work item isn't queued and isn't running.
+ * In such cases you should use cancel_delayed_work_sync() or
+ * cancel_work_sync() instead.
+ */
+void flush_scheduled_work(void)
+{
+ flush_workqueue(system_wq);
+}
+EXPORT_SYMBOL(flush_scheduled_work);
+
+/**
+ * execute_in_process_context - reliably execute the routine with user context
+ * @fn: the function to execute
+ * @ew: guaranteed storage for the execute work structure (must
+ * be available when the work executes)
+ *
+ * Executes the function immediately if process context is available,
+ * otherwise schedules the function for delayed execution.
+ *
+ * Return: 0 - function was executed
+ * 1 - function was scheduled for execution
+ */
+int execute_in_process_context(work_func_t fn, struct execute_work *ew)
+{
+ if (!in_interrupt()) {
+ fn(&ew->work);
+ return 0;
+ }
+
+ INIT_WORK(&ew->work, fn);
+ schedule_work(&ew->work);
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(execute_in_process_context);
+
+/**
+ * free_workqueue_attrs - free a workqueue_attrs
+ * @attrs: workqueue_attrs to free
+ *
+ * Undo alloc_workqueue_attrs().
+ */
+void free_workqueue_attrs(struct workqueue_attrs *attrs)
+{
+ if (attrs) {
+ free_cpumask_var(attrs->cpumask);
+ kfree(attrs);
+ }
+}
+
+/**
+ * alloc_workqueue_attrs - allocate a workqueue_attrs
+ * @gfp_mask: allocation mask to use
+ *
+ * Allocate a new workqueue_attrs, initialize with default settings and
+ * return it.
+ *
+ * Return: The allocated new workqueue_attr on success. %NULL on failure.
+ */
+struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
+{
+ struct workqueue_attrs *attrs;
+
+ attrs = kzalloc(sizeof(*attrs), gfp_mask);
+ if (!attrs)
+ goto fail;
+ if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
+ goto fail;
+
+ cpumask_copy(attrs->cpumask, cpu_possible_mask);
+ return attrs;
+fail:
+ free_workqueue_attrs(attrs);
+ return NULL;
+}
+
+static void copy_workqueue_attrs(struct workqueue_attrs *to,
+ const struct workqueue_attrs *from)
+{
+ to->nice = from->nice;
+ cpumask_copy(to->cpumask, from->cpumask);
+ /*
+ * Unlike hash and equality test, this function doesn't ignore
+ * ->no_numa as it is used for both pool and wq attrs. Instead,
+ * get_unbound_pool() explicitly clears ->no_numa after copying.
+ */
+ to->no_numa = from->no_numa;
+}
+
+/* hash value of the content of @attr */
+static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
+{
+ u32 hash = 0;
+
+ hash = jhash_1word(attrs->nice, hash);
+ hash = jhash(cpumask_bits(attrs->cpumask),
+ BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
+ return hash;
+}
+
+/* content equality test */
+static bool wqattrs_equal(const struct workqueue_attrs *a,
+ const struct workqueue_attrs *b)
+{
+ if (a->nice != b->nice)
+ return false;
+ if (!cpumask_equal(a->cpumask, b->cpumask))
+ return false;
+ return true;
+}
+
+/**
+ * init_worker_pool - initialize a newly zalloc'd worker_pool
+ * @pool: worker_pool to initialize
+ *
+ * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
+ *
+ * Return: 0 on success, -errno on failure. Even on failure, all fields
+ * inside @pool proper are initialized and put_unbound_pool() can be called
+ * on @pool safely to release it.
+ */
+static int init_worker_pool(struct worker_pool *pool)
+{
+ spin_lock_init(&pool->lock);
+ pool->id = -1;
+ pool->cpu = -1;
+ pool->node = NUMA_NO_NODE;
+ pool->flags |= POOL_DISASSOCIATED;
+ INIT_LIST_HEAD(&pool->worklist);
+ INIT_LIST_HEAD(&pool->idle_list);
+ hash_init(pool->busy_hash);
+
+ init_timer_deferrable(&pool->idle_timer);
+ pool->idle_timer.function = idle_worker_timeout;
+ pool->idle_timer.data = (unsigned long)pool;
+
+ setup_timer(&pool->mayday_timer, pool_mayday_timeout,
+ (unsigned long)pool);
+
+ mutex_init(&pool->manager_arb);
+ mutex_init(&pool->attach_mutex);
+ INIT_LIST_HEAD(&pool->workers);
+
+ ida_init(&pool->worker_ida);
+ INIT_HLIST_NODE(&pool->hash_node);
+ pool->refcnt = 1;
+
+ /* shouldn't fail above this point */
+ pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ if (!pool->attrs)
+ return -ENOMEM;
+ return 0;
+}
+
+static void rcu_free_wq(struct rcu_head *rcu)
+{
+ struct workqueue_struct *wq =
+ container_of(rcu, struct workqueue_struct, rcu);
+
+ if (!(wq->flags & WQ_UNBOUND))
+ free_percpu(wq->cpu_pwqs);
+ else
+ free_workqueue_attrs(wq->unbound_attrs);
+
+ kfree(wq->rescuer);
+ kfree(wq);
+}
+
+static void rcu_free_pool(struct rcu_head *rcu)
+{
+ struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
+
+ ida_destroy(&pool->worker_ida);
+ free_workqueue_attrs(pool->attrs);
+ kfree(pool);
+}
+
+/**
+ * put_unbound_pool - put a worker_pool
+ * @pool: worker_pool to put
+ *
+ * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU
+ * safe manner. get_unbound_pool() calls this function on its failure path
+ * and this function should be able to release pools which went through,
+ * successfully or not, init_worker_pool().
+ *
+ * Should be called with wq_pool_mutex held.
+ */
+static void put_unbound_pool(struct worker_pool *pool)
+{
+ DECLARE_COMPLETION_ONSTACK(detach_completion);
+ struct worker *worker;
+
+ lockdep_assert_held(&wq_pool_mutex);
+
+ if (--pool->refcnt)
+ return;
+
+ /* sanity checks */
+ if (WARN_ON(!(pool->cpu < 0)) ||
+ WARN_ON(!list_empty(&pool->worklist)))
+ return;
+
+ /* release id and unhash */
+ if (pool->id >= 0)
+ idr_remove(&worker_pool_idr, pool->id);
+ hash_del(&pool->hash_node);
+
+ /*
+ * Become the manager and destroy all workers. Grabbing
+ * manager_arb prevents @pool's workers from blocking on
+ * attach_mutex.
+ */
+ mutex_lock(&pool->manager_arb);
+
+ spin_lock_irq(&pool->lock);
+ while ((worker = first_idle_worker(pool)))
+ destroy_worker(worker);
+ WARN_ON(pool->nr_workers || pool->nr_idle);
+ spin_unlock_irq(&pool->lock);
+
+ mutex_lock(&pool->attach_mutex);
+ if (!list_empty(&pool->workers))
+ pool->detach_completion = &detach_completion;
+ mutex_unlock(&pool->attach_mutex);
+
+ if (pool->detach_completion)
+ wait_for_completion(pool->detach_completion);
+
+ mutex_unlock(&pool->manager_arb);
+
+ /* shut down the timers */
+ del_timer_sync(&pool->idle_timer);
+ del_timer_sync(&pool->mayday_timer);
+
+ /* RCU protected to allow dereferences from get_work_pool() */
+ call_rcu(&pool->rcu, rcu_free_pool);
+}
+
+/**
+ * get_unbound_pool - get a worker_pool with the specified attributes
+ * @attrs: the attributes of the worker_pool to get
+ *
+ * Obtain a worker_pool which has the same attributes as @attrs, bump the
+ * reference count and return it. If there already is a matching
+ * worker_pool, it will be used; otherwise, this function attempts to
+ * create a new one.
+ *
+ * Should be called with wq_pool_mutex held.
+ *
+ * Return: On success, a worker_pool with the same attributes as @attrs.
+ * On failure, %NULL.
+ */
+static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
+{
+ u32 hash = wqattrs_hash(attrs);
+ struct worker_pool *pool;
+ int node;
+
+ lockdep_assert_held(&wq_pool_mutex);
+
+ /* do we already have a matching pool? */
+ hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
+ if (wqattrs_equal(pool->attrs, attrs)) {
+ pool->refcnt++;
+ return pool;
+ }
+ }
+
+ /* nope, create a new one */
+ pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+ if (!pool || init_worker_pool(pool) < 0)
+ goto fail;
+
+ lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
+ copy_workqueue_attrs(pool->attrs, attrs);
+
+ /*
+ * no_numa isn't a worker_pool attribute, always clear it. See
+ * 'struct workqueue_attrs' comments for detail.
+ */
+ pool->attrs->no_numa = false;
+
+ /* if cpumask is contained inside a NUMA node, we belong to that node */
+ if (wq_numa_enabled) {
+ for_each_node(node) {
+ if (cpumask_subset(pool->attrs->cpumask,
+ wq_numa_possible_cpumask[node])) {
+ pool->node = node;
+ break;
+ }
+ }
+ }
+
+ if (worker_pool_assign_id(pool) < 0)
+ goto fail;
+
+ /* create and start the initial worker */
+ if (!create_worker(pool))
+ goto fail;
+
+ /* install */
+ hash_add(unbound_pool_hash, &pool->hash_node, hash);
+
+ return pool;
+fail:
+ if (pool)
+ put_unbound_pool(pool);
+ return NULL;
+}
+
+static void rcu_free_pwq(struct rcu_head *rcu)
+{
+ kmem_cache_free(pwq_cache,
+ container_of(rcu, struct pool_workqueue, rcu));
+}
+
+/*
+ * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
+ * and needs to be destroyed.
+ */
+static void pwq_unbound_release_workfn(struct work_struct *work)
+{
+ struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
+ unbound_release_work);
+ struct workqueue_struct *wq = pwq->wq;
+ struct worker_pool *pool = pwq->pool;
+ bool is_last;
+
+ if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
+ return;
+
+ mutex_lock(&wq->mutex);
+ list_del_rcu(&pwq->pwqs_node);
+ is_last = list_empty(&wq->pwqs);
+ mutex_unlock(&wq->mutex);
+
+ mutex_lock(&wq_pool_mutex);
+ put_unbound_pool(pool);
+ mutex_unlock(&wq_pool_mutex);
+
+ call_rcu(&pwq->rcu, rcu_free_pwq);
+
+ /*
+ * If we're the last pwq going away, @wq is already dead and no one
+ * is gonna access it anymore. Schedule RCU free.
+ */
+ if (is_last)
+ call_rcu(&wq->rcu, rcu_free_wq);
+}
+
+/**
+ * pwq_adjust_max_active - update a pwq's max_active to the current setting
+ * @pwq: target pool_workqueue
+ *
+ * If @pwq isn't freezing, set @pwq->max_active to the associated
+ * workqueue's saved_max_active and activate delayed work items
+ * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
+ */
+static void pwq_adjust_max_active(struct pool_workqueue *pwq)
+{
+ struct workqueue_struct *wq = pwq->wq;
+ bool freezable = wq->flags & WQ_FREEZABLE;
+
+ /* for @wq->saved_max_active */
+ lockdep_assert_held(&wq->mutex);
+
+ /* fast exit for non-freezable wqs */
+ if (!freezable && pwq->max_active == wq->saved_max_active)
+ return;
+
+ spin_lock_irq(&pwq->pool->lock);
+
+ /*
+ * During [un]freezing, the caller is responsible for ensuring that
+ * this function is called at least once after @workqueue_freezing
+ * is updated and visible.
+ */
+ if (!freezable || !workqueue_freezing) {
+ pwq->max_active = wq->saved_max_active;
+
+ while (!list_empty(&pwq->delayed_works) &&
+ pwq->nr_active < pwq->max_active)
+ pwq_activate_first_delayed(pwq);
+
+ /*
+ * Need to kick a worker after thawed or an unbound wq's
+ * max_active is bumped. It's a slow path. Do it always.
+ */
+ wake_up_worker(pwq->pool);
+ } else {
+ pwq->max_active = 0;
+ }
+
+ spin_unlock_irq(&pwq->pool->lock);
+}
+
+/* initialize newly alloced @pwq which is associated with @wq and @pool */
+static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
+ struct worker_pool *pool)
+{
+ BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
+
+ memset(pwq, 0, sizeof(*pwq));
+
+ pwq->pool = pool;
+ pwq->wq = wq;
+ pwq->flush_color = -1;
+ pwq->refcnt = 1;
+ INIT_LIST_HEAD(&pwq->delayed_works);
+ INIT_LIST_HEAD(&pwq->pwqs_node);
+ INIT_LIST_HEAD(&pwq->mayday_node);
+ INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
+}
+
+/* sync @pwq with the current state of its associated wq and link it */
+static void link_pwq(struct pool_workqueue *pwq)
+{
+ struct workqueue_struct *wq = pwq->wq;
+
+ lockdep_assert_held(&wq->mutex);
+
+ /* may be called multiple times, ignore if already linked */
+ if (!list_empty(&pwq->pwqs_node))
+ return;
+
+ /* set the matching work_color */
+ pwq->work_color = wq->work_color;
+
+ /* sync max_active to the current setting */
+ pwq_adjust_max_active(pwq);
+
+ /* link in @pwq */
+ list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
+}
+
+/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
+static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
+ const struct workqueue_attrs *attrs)
+{
+ struct worker_pool *pool;
+ struct pool_workqueue *pwq;
+
+ lockdep_assert_held(&wq_pool_mutex);
+
+ pool = get_unbound_pool(attrs);
+ if (!pool)
+ return NULL;
+
+ pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
+ if (!pwq) {
+ put_unbound_pool(pool);
+ return NULL;
+ }
+
+ init_pwq(pwq, wq, pool);
+ return pwq;
+}
+
+/* undo alloc_unbound_pwq(), used only in the error path */
+static void free_unbound_pwq(struct pool_workqueue *pwq)
+{
+ lockdep_assert_held(&wq_pool_mutex);
+
+ if (pwq) {
+ put_unbound_pool(pwq->pool);
+ kmem_cache_free(pwq_cache, pwq);
+ }
+}
+
+/**
+ * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
+ * @attrs: the wq_attrs of interest
+ * @node: the target NUMA node
+ * @cpu_going_down: if >= 0, the CPU to consider as offline
+ * @cpumask: outarg, the resulting cpumask
+ *
+ * Calculate the cpumask a workqueue with @attrs should use on @node. If
+ * @cpu_going_down is >= 0, that cpu is considered offline during
+ * calculation. The result is stored in @cpumask.
+ *
+ * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
+ * enabled and @node has online CPUs requested by @attrs, the returned
+ * cpumask is the intersection of the possible CPUs of @node and
+ * @attrs->cpumask.
+ *
+ * The caller is responsible for ensuring that the cpumask of @node stays
+ * stable.
+ *
+ * Return: %true if the resulting @cpumask is different from @attrs->cpumask,
+ * %false if equal.
+ */
+static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
+ int cpu_going_down, cpumask_t *cpumask)
+{
+ if (!wq_numa_enabled || attrs->no_numa)
+ goto use_dfl;
+
+ /* does @node have any online CPUs @attrs wants? */
+ cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
+ if (cpu_going_down >= 0)
+ cpumask_clear_cpu(cpu_going_down, cpumask);
+
+ if (cpumask_empty(cpumask))
+ goto use_dfl;
+
+ /* yeap, return possible CPUs in @node that @attrs wants */
+ cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
+ return !cpumask_equal(cpumask, attrs->cpumask);
+
+use_dfl:
+ cpumask_copy(cpumask, attrs->cpumask);
+ return false;
+}
+
+/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
+static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
+ int node,
+ struct pool_workqueue *pwq)
+{
+ struct pool_workqueue *old_pwq;
+
+ lockdep_assert_held(&wq->mutex);
+
+ /* link_pwq() can handle duplicate calls */
+ link_pwq(pwq);
+
+ old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
+ rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
+ return old_pwq;
+}
+
+/**
+ * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
+ * @wq: the target workqueue
+ * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
+ *
+ * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
+ * machines, this function maps a separate pwq to each NUMA node with
+ * possibles CPUs in @attrs->cpumask so that work items are affine to the
+ * NUMA node it was issued on. Older pwqs are released as in-flight work
+ * items finish. Note that a work item which repeatedly requeues itself
+ * back-to-back will stay on its current pwq.
+ *
+ * Performs GFP_KERNEL allocations.
+ *
+ * Return: 0 on success and -errno on failure.
+ */
+int apply_workqueue_attrs(struct workqueue_struct *wq,
+ const struct workqueue_attrs *attrs)
+{
+ struct workqueue_attrs *new_attrs, *tmp_attrs;
+ struct pool_workqueue **pwq_tbl, *dfl_pwq;
+ int node, ret;
+
+ /* only unbound workqueues can change attributes */
+ if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
+ return -EINVAL;
+
+ /* creating multiple pwqs breaks ordering guarantee */
+ if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
+ return -EINVAL;
+
+ pwq_tbl = kzalloc(nr_node_ids * sizeof(pwq_tbl[0]), GFP_KERNEL);
+ new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ if (!pwq_tbl || !new_attrs || !tmp_attrs)
+ goto enomem;
+
+ /* make a copy of @attrs and sanitize it */
+ copy_workqueue_attrs(new_attrs, attrs);
+ cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
+
+ /*
+ * We may create multiple pwqs with differing cpumasks. Make a
+ * copy of @new_attrs which will be modified and used to obtain
+ * pools.
+ */
+ copy_workqueue_attrs(tmp_attrs, new_attrs);
+
+ /*
+ * CPUs should stay stable across pwq creations and installations.
+ * Pin CPUs, determine the target cpumask for each node and create
+ * pwqs accordingly.
+ */
+ get_online_cpus();
+
+ mutex_lock(&wq_pool_mutex);
+
+ /*
+ * If something goes wrong during CPU up/down, we'll fall back to
+ * the default pwq covering whole @attrs->cpumask. Always create
+ * it even if we don't use it immediately.
+ */
+ dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
+ if (!dfl_pwq)
+ goto enomem_pwq;
+
+ for_each_node(node) {
+ if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) {
+ pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
+ if (!pwq_tbl[node])
+ goto enomem_pwq;
+ } else {
+ dfl_pwq->refcnt++;
+ pwq_tbl[node] = dfl_pwq;
+ }
+ }
+
+ mutex_unlock(&wq_pool_mutex);
+
+ /* all pwqs have been created successfully, let's install'em */
+ mutex_lock(&wq->mutex);
+
+ copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
+
+ /* save the previous pwq and install the new one */
+ for_each_node(node)
+ pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]);
+
+ /* @dfl_pwq might not have been used, ensure it's linked */
+ link_pwq(dfl_pwq);
+ swap(wq->dfl_pwq, dfl_pwq);
+
+ mutex_unlock(&wq->mutex);
+
+ /* put the old pwqs */
+ for_each_node(node)
+ put_pwq_unlocked(pwq_tbl[node]);
+ put_pwq_unlocked(dfl_pwq);
+
+ put_online_cpus();
+ ret = 0;
+ /* fall through */
+out_free:
+ free_workqueue_attrs(tmp_attrs);
+ free_workqueue_attrs(new_attrs);
+ kfree(pwq_tbl);
+ return ret;
+
+enomem_pwq:
+ free_unbound_pwq(dfl_pwq);
+ for_each_node(node)
+ if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
+ free_unbound_pwq(pwq_tbl[node]);
+ mutex_unlock(&wq_pool_mutex);
+ put_online_cpus();
+enomem:
+ ret = -ENOMEM;
+ goto out_free;
+}
+
+/**
+ * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
+ * @wq: the target workqueue
+ * @cpu: the CPU coming up or going down
+ * @online: whether @cpu is coming up or going down
+ *
+ * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
+ * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
+ * @wq accordingly.
+ *
+ * If NUMA affinity can't be adjusted due to memory allocation failure, it
+ * falls back to @wq->dfl_pwq which may not be optimal but is always
+ * correct.
+ *
+ * Note that when the last allowed CPU of a NUMA node goes offline for a
+ * workqueue with a cpumask spanning multiple nodes, the workers which were
+ * already executing the work items for the workqueue will lose their CPU
+ * affinity and may execute on any CPU. This is similar to how per-cpu
+ * workqueues behave on CPU_DOWN. If a workqueue user wants strict
+ * affinity, it's the user's responsibility to flush the work item from
+ * CPU_DOWN_PREPARE.
+ */
+static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
+ bool online)
+{
+ int node = cpu_to_node(cpu);
+ int cpu_off = online ? -1 : cpu;
+ struct pool_workqueue *old_pwq = NULL, *pwq;
+ struct workqueue_attrs *target_attrs;
+ cpumask_t *cpumask;
+
+ lockdep_assert_held(&wq_pool_mutex);
+
+ if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
+ return;
+
+ /*
+ * We don't wanna alloc/free wq_attrs for each wq for each CPU.
+ * Let's use a preallocated one. The following buf is protected by
+ * CPU hotplug exclusion.
+ */
+ target_attrs = wq_update_unbound_numa_attrs_buf;
+ cpumask = target_attrs->cpumask;
+
+ mutex_lock(&wq->mutex);
+ if (wq->unbound_attrs->no_numa)
+ goto out_unlock;
+
+ copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
+ pwq = unbound_pwq_by_node(wq, node);
+
+ /*
+ * Let's determine what needs to be done. If the target cpumask is
+ * different from wq's, we need to compare it to @pwq's and create
+ * a new one if they don't match. If the target cpumask equals
+ * wq's, the default pwq should be used.
+ */
+ if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) {
+ if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
+ goto out_unlock;
+ } else {
+ goto use_dfl_pwq;
+ }
+
+ mutex_unlock(&wq->mutex);
+
+ /* create a new pwq */
+ pwq = alloc_unbound_pwq(wq, target_attrs);
+ if (!pwq) {
+ pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
+ wq->name);
+ mutex_lock(&wq->mutex);
+ goto use_dfl_pwq;
+ }
+
+ /*
+ * Install the new pwq. As this function is called only from CPU
+ * hotplug callbacks and applying a new attrs is wrapped with
+ * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
+ * inbetween.
+ */
+ mutex_lock(&wq->mutex);
+ old_pwq = numa_pwq_tbl_install(wq, node, pwq);
+ goto out_unlock;
+
+use_dfl_pwq:
+ spin_lock_irq(&wq->dfl_pwq->pool->lock);
+ get_pwq(wq->dfl_pwq);
+ spin_unlock_irq(&wq->dfl_pwq->pool->lock);
+ old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
+out_unlock:
+ mutex_unlock(&wq->mutex);
+ put_pwq_unlocked(old_pwq);
+}
+
+static int alloc_and_link_pwqs(struct workqueue_struct *wq)
+{
+ bool highpri = wq->flags & WQ_HIGHPRI;
+ int cpu, ret;
+
+ if (!(wq->flags & WQ_UNBOUND)) {
+ wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
+ if (!wq->cpu_pwqs)
+ return -ENOMEM;
+
+ for_each_possible_cpu(cpu) {
+ struct pool_workqueue *pwq =
+ per_cpu_ptr(wq->cpu_pwqs, cpu);
+ struct worker_pool *cpu_pools =
+ per_cpu(cpu_worker_pools, cpu);
+
+ init_pwq(pwq, wq, &cpu_pools[highpri]);
+
+ mutex_lock(&wq->mutex);
+ link_pwq(pwq);
+ mutex_unlock(&wq->mutex);
+ }
+ return 0;
+ } else if (wq->flags & __WQ_ORDERED) {
+ ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
+ /* there should only be single pwq for ordering guarantee */
+ WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
+ wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
+ "ordering guarantee broken for workqueue %s\n", wq->name);
+ return ret;
+ } else {
+ return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
+ }
+}
+
+static int wq_clamp_max_active(int max_active, unsigned int flags,
+ const char *name)
+{
+ int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
+
+ if (max_active < 1 || max_active > lim)
+ pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
+ max_active, name, 1, lim);
+
+ return clamp_val(max_active, 1, lim);
+}
+
+struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
+ unsigned int flags,
+ int max_active,
+ struct lock_class_key *key,
+ const char *lock_name, ...)
+{
+ size_t tbl_size = 0;
+ va_list args;
+ struct workqueue_struct *wq;
+ struct pool_workqueue *pwq;
+
+ /* see the comment above the definition of WQ_POWER_EFFICIENT */
+ if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
+ flags |= WQ_UNBOUND;
+
+ /* allocate wq and format name */
+ if (flags & WQ_UNBOUND)
+ tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]);
+
+ wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
+ if (!wq)
+ return NULL;
+
+ if (flags & WQ_UNBOUND) {
+ wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ if (!wq->unbound_attrs)
+ goto err_free_wq;
+ }
+
+ va_start(args, lock_name);
+ vsnprintf(wq->name, sizeof(wq->name), fmt, args);
+ va_end(args);
+
+ max_active = max_active ?: WQ_DFL_ACTIVE;
+ max_active = wq_clamp_max_active(max_active, flags, wq->name);
+
+ /* init wq */
+ wq->flags = flags;
+ wq->saved_max_active = max_active;
+ mutex_init(&wq->mutex);
+ atomic_set(&wq->nr_pwqs_to_flush, 0);
+ INIT_LIST_HEAD(&wq->pwqs);
+ INIT_LIST_HEAD(&wq->flusher_queue);
+ INIT_LIST_HEAD(&wq->flusher_overflow);
+ INIT_LIST_HEAD(&wq->maydays);
+
+ lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
+ INIT_LIST_HEAD(&wq->list);
+
+ if (alloc_and_link_pwqs(wq) < 0)
+ goto err_free_wq;
+
+ /*
+ * Workqueues which may be used during memory reclaim should
+ * have a rescuer to guarantee forward progress.
+ */
+ if (flags & WQ_MEM_RECLAIM) {
+ struct worker *rescuer;
+
+ rescuer = alloc_worker(NUMA_NO_NODE);
+ if (!rescuer)
+ goto err_destroy;
+
+ rescuer->rescue_wq = wq;
+ rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
+ wq->name);
+ if (IS_ERR(rescuer->task)) {
+ kfree(rescuer);
+ goto err_destroy;
+ }
+
+ wq->rescuer = rescuer;
+ rescuer->task->flags |= PF_NO_SETAFFINITY;
+ wake_up_process(rescuer->task);
+ }
+
+ if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
+ goto err_destroy;
+
+ /*
+ * wq_pool_mutex protects global freeze state and workqueues list.
+ * Grab it, adjust max_active and add the new @wq to workqueues
+ * list.
+ */
+ mutex_lock(&wq_pool_mutex);
+
+ mutex_lock(&wq->mutex);
+ for_each_pwq(pwq, wq)
+ pwq_adjust_max_active(pwq);
+ mutex_unlock(&wq->mutex);
+
+ list_add_tail_rcu(&wq->list, &workqueues);
+
+ mutex_unlock(&wq_pool_mutex);
+
+ return wq;
+
+err_free_wq:
+ free_workqueue_attrs(wq->unbound_attrs);
+ kfree(wq);
+ return NULL;
+err_destroy:
+ destroy_workqueue(wq);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
+
+/**
+ * destroy_workqueue - safely terminate a workqueue
+ * @wq: target workqueue
+ *
+ * Safely destroy a workqueue. All work currently pending will be done first.
+ */
+void destroy_workqueue(struct workqueue_struct *wq)
+{
+ struct pool_workqueue *pwq;
+ int node;
+
+ /* drain it before proceeding with destruction */
+ drain_workqueue(wq);
+
+ /* sanity checks */
+ mutex_lock(&wq->mutex);
+ for_each_pwq(pwq, wq) {
+ int i;
+
+ for (i = 0; i < WORK_NR_COLORS; i++) {
+ if (WARN_ON(pwq->nr_in_flight[i])) {
+ mutex_unlock(&wq->mutex);
+ return;
+ }
+ }
+
+ if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
+ WARN_ON(pwq->nr_active) ||
+ WARN_ON(!list_empty(&pwq->delayed_works))) {
+ mutex_unlock(&wq->mutex);
+ return;
+ }
+ }
+ mutex_unlock(&wq->mutex);
+
+ /*
+ * wq list is used to freeze wq, remove from list after
+ * flushing is complete in case freeze races us.
+ */
+ mutex_lock(&wq_pool_mutex);
+ list_del_rcu(&wq->list);
+ mutex_unlock(&wq_pool_mutex);
+
+ workqueue_sysfs_unregister(wq);
+
+ if (wq->rescuer)
+ kthread_stop(wq->rescuer->task);
+
+ if (!(wq->flags & WQ_UNBOUND)) {
+ /*
+ * The base ref is never dropped on per-cpu pwqs. Directly
+ * schedule RCU free.
+ */
+ call_rcu(&wq->rcu, rcu_free_wq);
+ } else {
+ /*
+ * We're the sole accessor of @wq at this point. Directly
+ * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
+ * @wq will be freed when the last pwq is released.
+ */
+ for_each_node(node) {
+ pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
+ RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
+ put_pwq_unlocked(pwq);
+ }
+
+ /*
+ * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
+ * put. Don't access it afterwards.
+ */
+ pwq = wq->dfl_pwq;
+ wq->dfl_pwq = NULL;
+ put_pwq_unlocked(pwq);
+ }
+}
+EXPORT_SYMBOL_GPL(destroy_workqueue);
+
+/**
+ * workqueue_set_max_active - adjust max_active of a workqueue
+ * @wq: target workqueue
+ * @max_active: new max_active value.
+ *
+ * Set max_active of @wq to @max_active.
+ *
+ * CONTEXT:
+ * Don't call from IRQ context.
+ */
+void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
+{
+ struct pool_workqueue *pwq;
+
+ /* disallow meddling with max_active for ordered workqueues */
+ if (WARN_ON(wq->flags & __WQ_ORDERED))
+ return;
+
+ max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
+
+ mutex_lock(&wq->mutex);
+
+ wq->saved_max_active = max_active;
+
+ for_each_pwq(pwq, wq)
+ pwq_adjust_max_active(pwq);
+
+ mutex_unlock(&wq->mutex);
+}
+EXPORT_SYMBOL_GPL(workqueue_set_max_active);
+
+/**
+ * current_is_workqueue_rescuer - is %current workqueue rescuer?
+ *
+ * Determine whether %current is a workqueue rescuer. Can be used from
+ * work functions to determine whether it's being run off the rescuer task.
+ *
+ * Return: %true if %current is a workqueue rescuer. %false otherwise.
+ */
+bool current_is_workqueue_rescuer(void)
+{
+ struct worker *worker = current_wq_worker();
+
+ return worker && worker->rescue_wq;
+}
+
+/**
+ * workqueue_congested - test whether a workqueue is congested
+ * @cpu: CPU in question
+ * @wq: target workqueue
+ *
+ * Test whether @wq's cpu workqueue for @cpu is congested. There is
+ * no synchronization around this function and the test result is
+ * unreliable and only useful as advisory hints or for debugging.
+ *
+ * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
+ * Note that both per-cpu and unbound workqueues may be associated with
+ * multiple pool_workqueues which have separate congested states. A
+ * workqueue being congested on one CPU doesn't mean the workqueue is also
+ * contested on other CPUs / NUMA nodes.
+ *
+ * Return:
+ * %true if congested, %false otherwise.
+ */
+bool workqueue_congested(int cpu, struct workqueue_struct *wq)
+{
+ struct pool_workqueue *pwq;
+ bool ret;
+
+ rcu_read_lock();
+ preempt_disable();
+
+ if (cpu == WORK_CPU_UNBOUND)
+ cpu = smp_processor_id();
+
+ if (!(wq->flags & WQ_UNBOUND))
+ pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
+ else
+ pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
+
+ ret = !list_empty(&pwq->delayed_works);
+ preempt_enable();
+ rcu_read_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(workqueue_congested);
+
+/**
+ * work_busy - test whether a work is currently pending or running
+ * @work: the work to be tested
+ *
+ * Test whether @work is currently pending or running. There is no
+ * synchronization around this function and the test result is
+ * unreliable and only useful as advisory hints or for debugging.
+ *
+ * Return:
+ * OR'd bitmask of WORK_BUSY_* bits.
+ */
+unsigned int work_busy(struct work_struct *work)
+{
+ struct worker_pool *pool;
+ unsigned long flags;
+ unsigned int ret = 0;
+
+ if (work_pending(work))
+ ret |= WORK_BUSY_PENDING;
+
+ rcu_read_lock();
+ pool = get_work_pool(work);
+ if (pool) {
+ spin_lock_irqsave(&pool->lock, flags);
+ if (find_worker_executing_work(pool, work))
+ ret |= WORK_BUSY_RUNNING;
+ spin_unlock_irqrestore(&pool->lock, flags);
+ }
+ rcu_read_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(work_busy);
+
+/**
+ * set_worker_desc - set description for the current work item
+ * @fmt: printf-style format string
+ * @...: arguments for the format string
+ *
+ * This function can be called by a running work function to describe what
+ * the work item is about. If the worker task gets dumped, this
+ * information will be printed out together to help debugging. The
+ * description can be at most WORKER_DESC_LEN including the trailing '\0'.
+ */
+void set_worker_desc(const char *fmt, ...)
+{
+ struct worker *worker = current_wq_worker();
+ va_list args;
+
+ if (worker) {
+ va_start(args, fmt);
+ vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
+ va_end(args);
+ worker->desc_valid = true;
+ }
+}
+
+/**
+ * print_worker_info - print out worker information and description
+ * @log_lvl: the log level to use when printing
+ * @task: target task
+ *
+ * If @task is a worker and currently executing a work item, print out the
+ * name of the workqueue being serviced and worker description set with
+ * set_worker_desc() by the currently executing work item.
+ *
+ * This function can be safely called on any task as long as the
+ * task_struct itself is accessible. While safe, this function isn't
+ * synchronized and may print out mixups or garbages of limited length.
+ */
+void print_worker_info(const char *log_lvl, struct task_struct *task)
+{
+ work_func_t *fn = NULL;
+ char name[WQ_NAME_LEN] = { };
+ char desc[WORKER_DESC_LEN] = { };
+ struct pool_workqueue *pwq = NULL;
+ struct workqueue_struct *wq = NULL;
+ bool desc_valid = false;
+ struct worker *worker;
+
+ if (!(task->flags & PF_WQ_WORKER))
+ return;
+
+ /*
+ * This function is called without any synchronization and @task
+ * could be in any state. Be careful with dereferences.
+ */
+ worker = probe_kthread_data(task);
+
+ /*
+ * Carefully copy the associated workqueue's workfn and name. Keep
+ * the original last '\0' in case the original contains garbage.
+ */
+ probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
+ probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
+ probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
+ probe_kernel_read(name, wq->name, sizeof(name) - 1);
+
+ /* copy worker description */
+ probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid));
+ if (desc_valid)
+ probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
+
+ if (fn || name[0] || desc[0]) {
+ printk("%sWorkqueue: %s %pf", log_lvl, name, fn);
+ if (desc[0])
+ pr_cont(" (%s)", desc);
+ pr_cont("\n");
+ }
+}
+
+static void pr_cont_pool_info(struct worker_pool *pool)
+{
+ pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask);
+ if (pool->node != NUMA_NO_NODE)
+ pr_cont(" node=%d", pool->node);
+ pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice);
+}
+
+static void pr_cont_work(bool comma, struct work_struct *work)
+{
+ if (work->func == wq_barrier_func) {
+ struct wq_barrier *barr;
+
+ barr = container_of(work, struct wq_barrier, work);
+
+ pr_cont("%s BAR(%d)", comma ? "," : "",
+ task_pid_nr(barr->task));
+ } else {
+ pr_cont("%s %pf", comma ? "," : "", work->func);
+ }
+}
+
+static void show_pwq(struct pool_workqueue *pwq)
+{
+ struct worker_pool *pool = pwq->pool;
+ struct work_struct *work;
+ struct worker *worker;
+ bool has_in_flight = false, has_pending = false;
+ int bkt;
+
+ pr_info(" pwq %d:", pool->id);
+ pr_cont_pool_info(pool);
+
+ pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active,
+ !list_empty(&pwq->mayday_node) ? " MAYDAY" : "");
+
+ hash_for_each(pool->busy_hash, bkt, worker, hentry) {
+ if (worker->current_pwq == pwq) {
+ has_in_flight = true;
+ break;
+ }
+ }
+ if (has_in_flight) {
+ bool comma = false;
+
+ pr_info(" in-flight:");
+ hash_for_each(pool->busy_hash, bkt, worker, hentry) {
+ if (worker->current_pwq != pwq)
+ continue;
+
+ pr_cont("%s %d%s:%pf", comma ? "," : "",
+ task_pid_nr(worker->task),
+ worker == pwq->wq->rescuer ? "(RESCUER)" : "",
+ worker->current_func);
+ list_for_each_entry(work, &worker->scheduled, entry)
+ pr_cont_work(false, work);
+ comma = true;
+ }
+ pr_cont("\n");
+ }
+
+ list_for_each_entry(work, &pool->worklist, entry) {
+ if (get_work_pwq(work) == pwq) {
+ has_pending = true;
+ break;
+ }
+ }
+ if (has_pending) {
+ bool comma = false;
+
+ pr_info(" pending:");
+ list_for_each_entry(work, &pool->worklist, entry) {
+ if (get_work_pwq(work) != pwq)
+ continue;
+
+ pr_cont_work(comma, work);
+ comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
+ }
+ pr_cont("\n");
+ }
+
+ if (!list_empty(&pwq->delayed_works)) {
+ bool comma = false;
+
+ pr_info(" delayed:");
+ list_for_each_entry(work, &pwq->delayed_works, entry) {
+ pr_cont_work(comma, work);
+ comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
+ }
+ pr_cont("\n");
+ }
+}
+
+/**
+ * show_workqueue_state - dump workqueue state
+ *
+ * Called from a sysrq handler and prints out all busy workqueues and
+ * pools.
+ */
+void show_workqueue_state(void)
+{
+ struct workqueue_struct *wq;
+ struct worker_pool *pool;
+ unsigned long flags;
+ int pi;
+
+ rcu_read_lock();
+
+ pr_info("Showing busy workqueues and worker pools:\n");
+
+ list_for_each_entry_rcu(wq, &workqueues, list) {
+ struct pool_workqueue *pwq;
+ bool idle = true;
+
+ for_each_pwq(pwq, wq) {
+ if (pwq->nr_active || !list_empty(&pwq->delayed_works)) {
+ idle = false;
+ break;
+ }
+ }
+ if (idle)
+ continue;
+
+ pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);
+
+ for_each_pwq(pwq, wq) {
+ spin_lock_irqsave(&pwq->pool->lock, flags);
+ if (pwq->nr_active || !list_empty(&pwq->delayed_works))
+ show_pwq(pwq);
+ spin_unlock_irqrestore(&pwq->pool->lock, flags);
+ }
+ }
+
+ for_each_pool(pool, pi) {
+ struct worker *worker;
+ bool first = true;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ if (pool->nr_workers == pool->nr_idle)
+ goto next_pool;
+
+ pr_info("pool %d:", pool->id);
+ pr_cont_pool_info(pool);
+ pr_cont(" workers=%d", pool->nr_workers);
+ if (pool->manager)
+ pr_cont(" manager: %d",
+ task_pid_nr(pool->manager->task));
+ list_for_each_entry(worker, &pool->idle_list, entry) {
+ pr_cont(" %s%d", first ? "idle: " : "",
+ task_pid_nr(worker->task));
+ first = false;
+ }
+ pr_cont("\n");
+ next_pool:
+ spin_unlock_irqrestore(&pool->lock, flags);
+ }
+
+ rcu_read_unlock();
+}
+
+/*
+ * CPU hotplug.
+ *
+ * There are two challenges in supporting CPU hotplug. Firstly, there
+ * are a lot of assumptions on strong associations among work, pwq and
+ * pool which make migrating pending and scheduled works very
+ * difficult to implement without impacting hot paths. Secondly,
+ * worker pools serve mix of short, long and very long running works making
+ * blocked draining impractical.
+ *
+ * This is solved by allowing the pools to be disassociated from the CPU
+ * running as an unbound one and allowing it to be reattached later if the
+ * cpu comes back online.
+ */
+
+static void wq_unbind_fn(struct work_struct *work)
+{
+ int cpu = smp_processor_id();
+ struct worker_pool *pool;
+ struct worker *worker;
+
+ for_each_cpu_worker_pool(pool, cpu) {
+ mutex_lock(&pool->attach_mutex);
+ spin_lock_irq(&pool->lock);
+
+ /*
+ * We've blocked all attach/detach operations. Make all workers
+ * unbound and set DISASSOCIATED. Before this, all workers
+ * except for the ones which are still executing works from
+ * before the last CPU down must be on the cpu. After
+ * this, they may become diasporas.
+ */
+ for_each_pool_worker(worker, pool)
+ worker->flags |= WORKER_UNBOUND;
+
+ pool->flags |= POOL_DISASSOCIATED;
+
+ spin_unlock_irq(&pool->lock);
+ mutex_unlock(&pool->attach_mutex);
+
+ /*
+ * Call schedule() so that we cross rq->lock and thus can
+ * guarantee sched callbacks see the %WORKER_UNBOUND flag.
+ * This is necessary as scheduler callbacks may be invoked
+ * from other cpus.
+ */
+ schedule();
+
+ /*
+ * Sched callbacks are disabled now. Zap nr_running.
+ * After this, nr_running stays zero and need_more_worker()
+ * and keep_working() are always true as long as the
+ * worklist is not empty. This pool now behaves as an
+ * unbound (in terms of concurrency management) pool which
+ * are served by workers tied to the pool.
+ */
+ atomic_set(&pool->nr_running, 0);
+
+ /*
+ * With concurrency management just turned off, a busy
+ * worker blocking could lead to lengthy stalls. Kick off
+ * unbound chain execution of currently pending work items.
+ */
+ spin_lock_irq(&pool->lock);
+ wake_up_worker(pool);
+ spin_unlock_irq(&pool->lock);
+ }
+}
+
+/**
+ * rebind_workers - rebind all workers of a pool to the associated CPU
+ * @pool: pool of interest
+ *
+ * @pool->cpu is coming online. Rebind all workers to the CPU.
+ */
+static void rebind_workers(struct worker_pool *pool)
+{
+ struct worker *worker;
+
+ lockdep_assert_held(&pool->attach_mutex);
+
+ /*
+ * Restore CPU affinity of all workers. As all idle workers should
+ * be on the run-queue of the associated CPU before any local
+ * wake-ups for concurrency management happen, restore CPU affinty
+ * of all workers first and then clear UNBOUND. As we're called
+ * from CPU_ONLINE, the following shouldn't fail.
+ */
+ for_each_pool_worker(worker, pool)
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
+ pool->attrs->cpumask) < 0);
+
+ spin_lock_irq(&pool->lock);
+ pool->flags &= ~POOL_DISASSOCIATED;
+
+ for_each_pool_worker(worker, pool) {
+ unsigned int worker_flags = worker->flags;
+
+ /*
+ * A bound idle worker should actually be on the runqueue
+ * of the associated CPU for local wake-ups targeting it to
+ * work. Kick all idle workers so that they migrate to the
+ * associated CPU. Doing this in the same loop as
+ * replacing UNBOUND with REBOUND is safe as no worker will
+ * be bound before @pool->lock is released.
+ */
+ if (worker_flags & WORKER_IDLE)
+ wake_up_process(worker->task);
+
+ /*
+ * We want to clear UNBOUND but can't directly call
+ * worker_clr_flags() or adjust nr_running. Atomically
+ * replace UNBOUND with another NOT_RUNNING flag REBOUND.
+ * @worker will clear REBOUND using worker_clr_flags() when
+ * it initiates the next execution cycle thus restoring
+ * concurrency management. Note that when or whether
+ * @worker clears REBOUND doesn't affect correctness.
+ *
+ * ACCESS_ONCE() is necessary because @worker->flags may be
+ * tested without holding any lock in
+ * wq_worker_waking_up(). Without it, NOT_RUNNING test may
+ * fail incorrectly leading to premature concurrency
+ * management operations.
+ */
+ WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
+ worker_flags |= WORKER_REBOUND;
+ worker_flags &= ~WORKER_UNBOUND;
+ ACCESS_ONCE(worker->flags) = worker_flags;
+ }
+
+ spin_unlock_irq(&pool->lock);
+}
+
+/**
+ * restore_unbound_workers_cpumask - restore cpumask of unbound workers
+ * @pool: unbound pool of interest
+ * @cpu: the CPU which is coming up
+ *
+ * An unbound pool may end up with a cpumask which doesn't have any online
+ * CPUs. When a worker of such pool get scheduled, the scheduler resets
+ * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
+ * online CPU before, cpus_allowed of all its workers should be restored.
+ */
+static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
+{
+ static cpumask_t cpumask;
+ struct worker *worker;
+
+ lockdep_assert_held(&pool->attach_mutex);
+
+ /* is @cpu allowed for @pool? */
+ if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
+ return;
+
+ /* is @cpu the only online CPU? */
+ cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
+ if (cpumask_weight(&cpumask) != 1)
+ return;
+
+ /* as we're called from CPU_ONLINE, the following shouldn't fail */
+ for_each_pool_worker(worker, pool)
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
+ pool->attrs->cpumask) < 0);
+}
+
+/*
+ * Workqueues should be brought up before normal priority CPU notifiers.
+ * This will be registered high priority CPU notifier.
+ */
+static int workqueue_cpu_up_callback(struct notifier_block *nfb,
+ unsigned long action,
+ void *hcpu)
+{
+ int cpu = (unsigned long)hcpu;
+ struct worker_pool *pool;
+ struct workqueue_struct *wq;
+ int pi;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_UP_PREPARE:
+ for_each_cpu_worker_pool(pool, cpu) {
+ if (pool->nr_workers)
+ continue;
+ if (!create_worker(pool))
+ return NOTIFY_BAD;
+ }
+ break;
+
+ case CPU_DOWN_FAILED:
+ case CPU_ONLINE:
+ mutex_lock(&wq_pool_mutex);
+
+ for_each_pool(pool, pi) {
+ mutex_lock(&pool->attach_mutex);
+
+ if (pool->cpu == cpu)
+ rebind_workers(pool);
+ else if (pool->cpu < 0)
+ restore_unbound_workers_cpumask(pool, cpu);
+
+ mutex_unlock(&pool->attach_mutex);
+ }
+
+ /* update NUMA affinity of unbound workqueues */
+ list_for_each_entry(wq, &workqueues, list)
+ wq_update_unbound_numa(wq, cpu, true);
+
+ mutex_unlock(&wq_pool_mutex);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+/*
+ * Workqueues should be brought down after normal priority CPU notifiers.
+ * This will be registered as low priority CPU notifier.
+ */
+static int workqueue_cpu_down_callback(struct notifier_block *nfb,
+ unsigned long action,
+ void *hcpu)
+{
+ int cpu = (unsigned long)hcpu;
+ struct work_struct unbind_work;
+ struct workqueue_struct *wq;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_DOWN_PREPARE:
+ /* unbinding per-cpu workers should happen on the local CPU */
+ INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
+ queue_work_on(cpu, system_highpri_wq, &unbind_work);
+
+ /* update NUMA affinity of unbound workqueues */
+ mutex_lock(&wq_pool_mutex);
+ list_for_each_entry(wq, &workqueues, list)
+ wq_update_unbound_numa(wq, cpu, false);
+ mutex_unlock(&wq_pool_mutex);
+
+ /* wait for per-cpu unbinding to finish */
+ flush_work(&unbind_work);
+ destroy_work_on_stack(&unbind_work);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+#ifdef CONFIG_SMP
+
+struct work_for_cpu {
+ struct work_struct work;
+ long (*fn)(void *);
+ void *arg;
+ long ret;
+};
+
+static void work_for_cpu_fn(struct work_struct *work)
+{
+ struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
+
+ wfc->ret = wfc->fn(wfc->arg);
+}
+
+/**
+ * work_on_cpu - run a function in user context on a particular cpu
+ * @cpu: the cpu to run on
+ * @fn: the function to run
+ * @arg: the function arg
+ *
+ * It is up to the caller to ensure that the cpu doesn't go offline.
+ * The caller must not hold any locks which would prevent @fn from completing.
+ *
+ * Return: The value @fn returns.
+ */
+long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
+{
+ struct work_for_cpu wfc = { .fn = fn, .arg = arg };
+
+ INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
+ schedule_work_on(cpu, &wfc.work);
+ flush_work(&wfc.work);
+ destroy_work_on_stack(&wfc.work);
+ return wfc.ret;
+}
+EXPORT_SYMBOL_GPL(work_on_cpu);
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_FREEZER
+
+/**
+ * freeze_workqueues_begin - begin freezing workqueues
+ *
+ * Start freezing workqueues. After this function returns, all freezable
+ * workqueues will queue new works to their delayed_works list instead of
+ * pool->worklist.
+ *
+ * CONTEXT:
+ * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
+ */
+void freeze_workqueues_begin(void)
+{
+ struct workqueue_struct *wq;
+ struct pool_workqueue *pwq;
+
+ mutex_lock(&wq_pool_mutex);
+
+ WARN_ON_ONCE(workqueue_freezing);
+ workqueue_freezing = true;
+
+ list_for_each_entry(wq, &workqueues, list) {
+ mutex_lock(&wq->mutex);
+ for_each_pwq(pwq, wq)
+ pwq_adjust_max_active(pwq);
+ mutex_unlock(&wq->mutex);
+ }
+
+ mutex_unlock(&wq_pool_mutex);
+}
+
+/**
+ * freeze_workqueues_busy - are freezable workqueues still busy?
+ *
+ * Check whether freezing is complete. This function must be called
+ * between freeze_workqueues_begin() and thaw_workqueues().
+ *
+ * CONTEXT:
+ * Grabs and releases wq_pool_mutex.
+ *
+ * Return:
+ * %true if some freezable workqueues are still busy. %false if freezing
+ * is complete.
+ */
+bool freeze_workqueues_busy(void)
+{
+ bool busy = false;
+ struct workqueue_struct *wq;
+ struct pool_workqueue *pwq;
+
+ mutex_lock(&wq_pool_mutex);
+
+ WARN_ON_ONCE(!workqueue_freezing);
+
+ list_for_each_entry(wq, &workqueues, list) {
+ if (!(wq->flags & WQ_FREEZABLE))
+ continue;
+ /*
+ * nr_active is monotonically decreasing. It's safe
+ * to peek without lock.
+ */
+ rcu_read_lock();
+ for_each_pwq(pwq, wq) {
+ WARN_ON_ONCE(pwq->nr_active < 0);
+ if (pwq->nr_active) {
+ busy = true;
+ rcu_read_unlock();
+ goto out_unlock;
+ }
+ }
+ rcu_read_unlock();
+ }
+out_unlock:
+ mutex_unlock(&wq_pool_mutex);
+ return busy;
+}
+
+/**
+ * thaw_workqueues - thaw workqueues
+ *
+ * Thaw workqueues. Normal queueing is restored and all collected
+ * frozen works are transferred to their respective pool worklists.
+ *
+ * CONTEXT:
+ * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
+ */
+void thaw_workqueues(void)
+{
+ struct workqueue_struct *wq;
+ struct pool_workqueue *pwq;
+
+ mutex_lock(&wq_pool_mutex);
+
+ if (!workqueue_freezing)
+ goto out_unlock;
+
+ workqueue_freezing = false;
+
+ /* restore max_active and repopulate worklist */
+ list_for_each_entry(wq, &workqueues, list) {
+ mutex_lock(&wq->mutex);
+ for_each_pwq(pwq, wq)
+ pwq_adjust_max_active(pwq);
+ mutex_unlock(&wq->mutex);
+ }
+
+out_unlock:
+ mutex_unlock(&wq_pool_mutex);
+}
+#endif /* CONFIG_FREEZER */
+
+#ifdef CONFIG_SYSFS
+/*
+ * Workqueues with WQ_SYSFS flag set is visible to userland via
+ * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
+ * following attributes.
+ *
+ * per_cpu RO bool : whether the workqueue is per-cpu or unbound
+ * max_active RW int : maximum number of in-flight work items
+ *
+ * Unbound workqueues have the following extra attributes.
+ *
+ * id RO int : the associated pool ID
+ * nice RW int : nice value of the workers
+ * cpumask RW mask : bitmask of allowed CPUs for the workers
+ */
+struct wq_device {
+ struct workqueue_struct *wq;
+ struct device dev;
+};
+
+static struct workqueue_struct *dev_to_wq(struct device *dev)
+{
+ struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
+
+ return wq_dev->wq;
+}
+
+static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
+}
+static DEVICE_ATTR_RO(per_cpu);
+
+static ssize_t max_active_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
+}
+
+static ssize_t max_active_store(struct device *dev,
+ struct device_attribute *attr, const char *buf,
+ size_t count)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ int val;
+
+ if (sscanf(buf, "%d", &val) != 1 || val <= 0)
+ return -EINVAL;
+
+ workqueue_set_max_active(wq, val);
+ return count;
+}
+static DEVICE_ATTR_RW(max_active);
+
+static struct attribute *wq_sysfs_attrs[] = {
+ &dev_attr_per_cpu.attr,
+ &dev_attr_max_active.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(wq_sysfs);
+
+static ssize_t wq_pool_ids_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ const char *delim = "";
+ int node, written = 0;
+
+ get_online_cpus();
+ rcu_read_lock();
+ for_each_node(node) {
+ written += scnprintf(buf + written, PAGE_SIZE - written,
+ "%s%d:%d", delim, node,
+ unbound_pwq_by_node(wq, node)->pool->id);
+ delim = " ";
+ }
+ written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
+ rcu_read_unlock();
+ put_online_cpus();
+
+ return written;
+}
+
+static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ int written;
+
+ mutex_lock(&wq->mutex);
+ written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
+ mutex_unlock(&wq->mutex);
+
+ return written;
+}
+
+/* prepare workqueue_attrs for sysfs store operations */
+static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
+{
+ struct workqueue_attrs *attrs;
+
+ attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ if (!attrs)
+ return NULL;
+
+ mutex_lock(&wq->mutex);
+ copy_workqueue_attrs(attrs, wq->unbound_attrs);
+ mutex_unlock(&wq->mutex);
+ return attrs;
+}
+
+static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ struct workqueue_attrs *attrs;
+ int ret;
+
+ attrs = wq_sysfs_prep_attrs(wq);
+ if (!attrs)
+ return -ENOMEM;
+
+ if (sscanf(buf, "%d", &attrs->nice) == 1 &&
+ attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
+ ret = apply_workqueue_attrs(wq, attrs);
+ else
+ ret = -EINVAL;
+
+ free_workqueue_attrs(attrs);
+ return ret ?: count;
+}
+
+static ssize_t wq_cpumask_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ int written;
+
+ mutex_lock(&wq->mutex);
+ written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
+ cpumask_pr_args(wq->unbound_attrs->cpumask));
+ mutex_unlock(&wq->mutex);
+ return written;
+}
+
+static ssize_t wq_cpumask_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ struct workqueue_attrs *attrs;
+ int ret;
+
+ attrs = wq_sysfs_prep_attrs(wq);
+ if (!attrs)
+ return -ENOMEM;
+
+ ret = cpumask_parse(buf, attrs->cpumask);
+ if (!ret)
+ ret = apply_workqueue_attrs(wq, attrs);
+
+ free_workqueue_attrs(attrs);
+ return ret ?: count;
+}
+
+static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ int written;
+
+ mutex_lock(&wq->mutex);
+ written = scnprintf(buf, PAGE_SIZE, "%d\n",
+ !wq->unbound_attrs->no_numa);
+ mutex_unlock(&wq->mutex);
+
+ return written;
+}
+
+static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ struct workqueue_attrs *attrs;
+ int v, ret;
+
+ attrs = wq_sysfs_prep_attrs(wq);
+ if (!attrs)
+ return -ENOMEM;
+
+ ret = -EINVAL;
+ if (sscanf(buf, "%d", &v) == 1) {
+ attrs->no_numa = !v;
+ ret = apply_workqueue_attrs(wq, attrs);
+ }
+
+ free_workqueue_attrs(attrs);
+ return ret ?: count;
+}
+
+static struct device_attribute wq_sysfs_unbound_attrs[] = {
+ __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
+ __ATTR(nice, 0644, wq_nice_show, wq_nice_store),
+ __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
+ __ATTR(numa, 0644, wq_numa_show, wq_numa_store),
+ __ATTR_NULL,
+};
+
+static struct bus_type wq_subsys = {
+ .name = "workqueue",
+ .dev_groups = wq_sysfs_groups,
+};
+
+static int __init wq_sysfs_init(void)
+{
+ return subsys_virtual_register(&wq_subsys, NULL);
+}
+core_initcall(wq_sysfs_init);
+
+static void wq_device_release(struct device *dev)
+{
+ struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
+
+ kfree(wq_dev);
+}
+
+/**
+ * workqueue_sysfs_register - make a workqueue visible in sysfs
+ * @wq: the workqueue to register
+ *
+ * Expose @wq in sysfs under /sys/bus/workqueue/devices.
+ * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
+ * which is the preferred method.
+ *
+ * Workqueue user should use this function directly iff it wants to apply
+ * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
+ * apply_workqueue_attrs() may race against userland updating the
+ * attributes.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int workqueue_sysfs_register(struct workqueue_struct *wq)
+{
+ struct wq_device *wq_dev;
+ int ret;
+
+ /*
+ * Adjusting max_active or creating new pwqs by applyting
+ * attributes breaks ordering guarantee. Disallow exposing ordered
+ * workqueues.
+ */
+ if (WARN_ON(wq->flags & __WQ_ORDERED))
+ return -EINVAL;
+
+ wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
+ if (!wq_dev)
+ return -ENOMEM;
+
+ wq_dev->wq = wq;
+ wq_dev->dev.bus = &wq_subsys;
+ wq_dev->dev.init_name = wq->name;
+ wq_dev->dev.release = wq_device_release;
+
+ /*
+ * unbound_attrs are created separately. Suppress uevent until
+ * everything is ready.
+ */
+ dev_set_uevent_suppress(&wq_dev->dev, true);
+
+ ret = device_register(&wq_dev->dev);
+ if (ret) {
+ kfree(wq_dev);
+ wq->wq_dev = NULL;
+ return ret;
+ }
+
+ if (wq->flags & WQ_UNBOUND) {
+ struct device_attribute *attr;
+
+ for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
+ ret = device_create_file(&wq_dev->dev, attr);
+ if (ret) {
+ device_unregister(&wq_dev->dev);
+ wq->wq_dev = NULL;
+ return ret;
+ }
+ }
+ }
+
+ dev_set_uevent_suppress(&wq_dev->dev, false);
+ kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
+ return 0;
+}
+
+/**
+ * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
+ * @wq: the workqueue to unregister
+ *
+ * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
+ */
+static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
+{
+ struct wq_device *wq_dev = wq->wq_dev;
+
+ if (!wq->wq_dev)
+ return;
+
+ wq->wq_dev = NULL;
+ device_unregister(&wq_dev->dev);
+}
+#else /* CONFIG_SYSFS */
+static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
+#endif /* CONFIG_SYSFS */
+
+static void __init wq_numa_init(void)
+{
+ cpumask_var_t *tbl;
+ int node, cpu;
+
+ if (num_possible_nodes() <= 1)
+ return;
+
+ if (wq_disable_numa) {
+ pr_info("workqueue: NUMA affinity support disabled\n");
+ return;
+ }
+
+ wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
+ BUG_ON(!wq_update_unbound_numa_attrs_buf);
+
+ /*
+ * We want masks of possible CPUs of each node which isn't readily
+ * available. Build one from cpu_to_node() which should have been
+ * fully initialized by now.
+ */
+ tbl = kzalloc(nr_node_ids * sizeof(tbl[0]), GFP_KERNEL);
+ BUG_ON(!tbl);
+
+ for_each_node(node)
+ BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
+ node_online(node) ? node : NUMA_NO_NODE));
+
+ for_each_possible_cpu(cpu) {
+ node = cpu_to_node(cpu);
+ if (WARN_ON(node == NUMA_NO_NODE)) {
+ pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
+ /* happens iff arch is bonkers, let's just proceed */
+ return;
+ }
+ cpumask_set_cpu(cpu, tbl[node]);
+ }
+
+ wq_numa_possible_cpumask = tbl;
+ wq_numa_enabled = true;
+}
+
+static int __init init_workqueues(void)
+{
+ int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
+ int i, cpu;
+
+ WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
+
+ pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
+
+ cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
+ hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
+
+ wq_numa_init();
+
+ /* initialize CPU pools */
+ for_each_possible_cpu(cpu) {
+ struct worker_pool *pool;
+
+ i = 0;
+ for_each_cpu_worker_pool(pool, cpu) {
+ BUG_ON(init_worker_pool(pool));
+ pool->cpu = cpu;
+ cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
+ pool->attrs->nice = std_nice[i++];
+ pool->node = cpu_to_node(cpu);
+
+ /* alloc pool ID */
+ mutex_lock(&wq_pool_mutex);
+ BUG_ON(worker_pool_assign_id(pool));
+ mutex_unlock(&wq_pool_mutex);
+ }
+ }
+
+ /* create the initial worker */
+ for_each_online_cpu(cpu) {
+ struct worker_pool *pool;
+
+ for_each_cpu_worker_pool(pool, cpu) {
+ pool->flags &= ~POOL_DISASSOCIATED;
+ BUG_ON(!create_worker(pool));
+ }
+ }
+
+ /* create default unbound and ordered wq attrs */
+ for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
+ struct workqueue_attrs *attrs;
+
+ BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
+ attrs->nice = std_nice[i];
+ unbound_std_wq_attrs[i] = attrs;
+
+ /*
+ * An ordered wq should have only one pwq as ordering is
+ * guaranteed by max_active which is enforced by pwqs.
+ * Turn off NUMA so that dfl_pwq is used for all nodes.
+ */
+ BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
+ attrs->nice = std_nice[i];
+ attrs->no_numa = true;
+ ordered_wq_attrs[i] = attrs;
+ }
+
+ system_wq = alloc_workqueue("events", 0, 0);
+ system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
+ system_long_wq = alloc_workqueue("events_long", 0, 0);
+ system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
+ WQ_UNBOUND_MAX_ACTIVE);
+ system_freezable_wq = alloc_workqueue("events_freezable",
+ WQ_FREEZABLE, 0);
+ system_power_efficient_wq = alloc_workqueue("events_power_efficient",
+ WQ_POWER_EFFICIENT, 0);
+ system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
+ WQ_FREEZABLE | WQ_POWER_EFFICIENT,
+ 0);
+ BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
+ !system_unbound_wq || !system_freezable_wq ||
+ !system_power_efficient_wq ||
+ !system_freezable_power_efficient_wq);
+ return 0;
+}
+early_initcall(init_workqueues);
Code Review / kvmfornfv.git / blobdiff