--- /dev/null
+/* flow.c: Generic flow cache.
+ *
+ * Copyright (C) 2003 Alexey N. Kuznetsov (kuznet@ms2.inr.ac.ru)
+ * Copyright (C) 2003 David S. Miller (davem@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/interrupt.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/completion.h>
+#include <linux/percpu.h>
+#include <linux/bitops.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/mutex.h>
+#include <net/flow.h>
+#include <linux/atomic.h>
+#include <linux/security.h>
+#include <net/net_namespace.h>
+
+struct flow_cache_entry {
+ union {
+ struct hlist_node hlist;
+ struct list_head gc_list;
+ } u;
+ struct net *net;
+ u16 family;
+ u8 dir;
+ u32 genid;
+ struct flowi key;
+ struct flow_cache_object *object;
+};
+
+struct flow_flush_info {
+ struct flow_cache *cache;
+ atomic_t cpuleft;
+ struct completion completion;
+};
+
+static struct kmem_cache *flow_cachep __read_mostly;
+
+#define flow_cache_hash_size(cache) (1 << (cache)->hash_shift)
+#define FLOW_HASH_RND_PERIOD (10 * 60 * HZ)
+
+static void flow_cache_new_hashrnd(unsigned long arg)
+{
+ struct flow_cache *fc = (void *) arg;
+ int i;
+
+ for_each_possible_cpu(i)
+ per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
+
+ fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+ add_timer(&fc->rnd_timer);
+}
+
+static int flow_entry_valid(struct flow_cache_entry *fle,
+ struct netns_xfrm *xfrm)
+{
+ if (atomic_read(&xfrm->flow_cache_genid) != fle->genid)
+ return 0;
+ if (fle->object && !fle->object->ops->check(fle->object))
+ return 0;
+ return 1;
+}
+
+static void flow_entry_kill(struct flow_cache_entry *fle,
+ struct netns_xfrm *xfrm)
+{
+ if (fle->object)
+ fle->object->ops->delete(fle->object);
+ kmem_cache_free(flow_cachep, fle);
+}
+
+static void flow_cache_gc_task(struct work_struct *work)
+{
+ struct list_head gc_list;
+ struct flow_cache_entry *fce, *n;
+ struct netns_xfrm *xfrm = container_of(work, struct netns_xfrm,
+ flow_cache_gc_work);
+
+ INIT_LIST_HEAD(&gc_list);
+ spin_lock_bh(&xfrm->flow_cache_gc_lock);
+ list_splice_tail_init(&xfrm->flow_cache_gc_list, &gc_list);
+ spin_unlock_bh(&xfrm->flow_cache_gc_lock);
+
+ list_for_each_entry_safe(fce, n, &gc_list, u.gc_list)
+ flow_entry_kill(fce, xfrm);
+}
+
+static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
+ int deleted, struct list_head *gc_list,
+ struct netns_xfrm *xfrm)
+{
+ if (deleted) {
+ fcp->hash_count -= deleted;
+ spin_lock_bh(&xfrm->flow_cache_gc_lock);
+ list_splice_tail(gc_list, &xfrm->flow_cache_gc_list);
+ spin_unlock_bh(&xfrm->flow_cache_gc_lock);
+ schedule_work(&xfrm->flow_cache_gc_work);
+ }
+}
+
+static void __flow_cache_shrink(struct flow_cache *fc,
+ struct flow_cache_percpu *fcp,
+ int shrink_to)
+{
+ struct flow_cache_entry *fle;
+ struct hlist_node *tmp;
+ LIST_HEAD(gc_list);
+ int i, deleted = 0;
+ struct netns_xfrm *xfrm = container_of(fc, struct netns_xfrm,
+ flow_cache_global);
+
+ for (i = 0; i < flow_cache_hash_size(fc); i++) {
+ int saved = 0;
+
+ hlist_for_each_entry_safe(fle, tmp,
+ &fcp->hash_table[i], u.hlist) {
+ if (saved < shrink_to &&
+ flow_entry_valid(fle, xfrm)) {
+ saved++;
+ } else {
+ deleted++;
+ hlist_del(&fle->u.hlist);
+ list_add_tail(&fle->u.gc_list, &gc_list);
+ }
+ }
+ }
+
+ flow_cache_queue_garbage(fcp, deleted, &gc_list, xfrm);
+}
+
+static void flow_cache_shrink(struct flow_cache *fc,
+ struct flow_cache_percpu *fcp)
+{
+ int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
+
+ __flow_cache_shrink(fc, fcp, shrink_to);
+}
+
+static void flow_new_hash_rnd(struct flow_cache *fc,
+ struct flow_cache_percpu *fcp)
+{
+ get_random_bytes(&fcp->hash_rnd, sizeof(u32));
+ fcp->hash_rnd_recalc = 0;
+ __flow_cache_shrink(fc, fcp, 0);
+}
+
+static u32 flow_hash_code(struct flow_cache *fc,
+ struct flow_cache_percpu *fcp,
+ const struct flowi *key,
+ size_t keysize)
+{
+ const u32 *k = (const u32 *) key;
+ const u32 length = keysize * sizeof(flow_compare_t) / sizeof(u32);
+
+ return jhash2(k, length, fcp->hash_rnd)
+ & (flow_cache_hash_size(fc) - 1);
+}
+
+/* I hear what you're saying, use memcmp. But memcmp cannot make
+ * important assumptions that we can here, such as alignment.
+ */
+static int flow_key_compare(const struct flowi *key1, const struct flowi *key2,
+ size_t keysize)
+{
+ const flow_compare_t *k1, *k1_lim, *k2;
+
+ k1 = (const flow_compare_t *) key1;
+ k1_lim = k1 + keysize;
+
+ k2 = (const flow_compare_t *) key2;
+
+ do {
+ if (*k1++ != *k2++)
+ return 1;
+ } while (k1 < k1_lim);
+
+ return 0;
+}
+
+struct flow_cache_object *
+flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
+ flow_resolve_t resolver, void *ctx)
+{
+ struct flow_cache *fc = &net->xfrm.flow_cache_global;
+ struct flow_cache_percpu *fcp;
+ struct flow_cache_entry *fle, *tfle;
+ struct flow_cache_object *flo;
+ size_t keysize;
+ unsigned int hash;
+
+ local_bh_disable();
+ fcp = this_cpu_ptr(fc->percpu);
+
+ fle = NULL;
+ flo = NULL;
+
+ keysize = flow_key_size(family);
+ if (!keysize)
+ goto nocache;
+
+ /* Packet really early in init? Making flow_cache_init a
+ * pre-smp initcall would solve this. --RR */
+ if (!fcp->hash_table)
+ goto nocache;
+
+ if (fcp->hash_rnd_recalc)
+ flow_new_hash_rnd(fc, fcp);
+
+ hash = flow_hash_code(fc, fcp, key, keysize);
+ hlist_for_each_entry(tfle, &fcp->hash_table[hash], u.hlist) {
+ if (tfle->net == net &&
+ tfle->family == family &&
+ tfle->dir == dir &&
+ flow_key_compare(key, &tfle->key, keysize) == 0) {
+ fle = tfle;
+ break;
+ }
+ }
+
+ if (unlikely(!fle)) {
+ if (fcp->hash_count > fc->high_watermark)
+ flow_cache_shrink(fc, fcp);
+
+ fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
+ if (fle) {
+ fle->net = net;
+ fle->family = family;
+ fle->dir = dir;
+ memcpy(&fle->key, key, keysize * sizeof(flow_compare_t));
+ fle->object = NULL;
+ hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
+ fcp->hash_count++;
+ }
+ } else if (likely(fle->genid == atomic_read(&net->xfrm.flow_cache_genid))) {
+ flo = fle->object;
+ if (!flo)
+ goto ret_object;
+ flo = flo->ops->get(flo);
+ if (flo)
+ goto ret_object;
+ } else if (fle->object) {
+ flo = fle->object;
+ flo->ops->delete(flo);
+ fle->object = NULL;
+ }
+
+nocache:
+ flo = NULL;
+ if (fle) {
+ flo = fle->object;
+ fle->object = NULL;
+ }
+ flo = resolver(net, key, family, dir, flo, ctx);
+ if (fle) {
+ fle->genid = atomic_read(&net->xfrm.flow_cache_genid);
+ if (!IS_ERR(flo))
+ fle->object = flo;
+ else
+ fle->genid--;
+ } else {
+ if (!IS_ERR_OR_NULL(flo))
+ flo->ops->delete(flo);
+ }
+ret_object:
+ local_bh_enable();
+ return flo;
+}
+EXPORT_SYMBOL(flow_cache_lookup);
+
+static void flow_cache_flush_tasklet(unsigned long data)
+{
+ struct flow_flush_info *info = (void *)data;
+ struct flow_cache *fc = info->cache;
+ struct flow_cache_percpu *fcp;
+ struct flow_cache_entry *fle;
+ struct hlist_node *tmp;
+ LIST_HEAD(gc_list);
+ int i, deleted = 0;
+ struct netns_xfrm *xfrm = container_of(fc, struct netns_xfrm,
+ flow_cache_global);
+
+ fcp = this_cpu_ptr(fc->percpu);
+ for (i = 0; i < flow_cache_hash_size(fc); i++) {
+ hlist_for_each_entry_safe(fle, tmp,
+ &fcp->hash_table[i], u.hlist) {
+ if (flow_entry_valid(fle, xfrm))
+ continue;
+
+ deleted++;
+ hlist_del(&fle->u.hlist);
+ list_add_tail(&fle->u.gc_list, &gc_list);
+ }
+ }
+
+ flow_cache_queue_garbage(fcp, deleted, &gc_list, xfrm);
+
+ if (atomic_dec_and_test(&info->cpuleft))
+ complete(&info->completion);
+}
+
+/*
+ * Return whether a cpu needs flushing. Conservatively, we assume
+ * the presence of any entries means the core may require flushing,
+ * since the flow_cache_ops.check() function may assume it's running
+ * on the same core as the per-cpu cache component.
+ */
+static int flow_cache_percpu_empty(struct flow_cache *fc, int cpu)
+{
+ struct flow_cache_percpu *fcp;
+ int i;
+
+ fcp = per_cpu_ptr(fc->percpu, cpu);
+ for (i = 0; i < flow_cache_hash_size(fc); i++)
+ if (!hlist_empty(&fcp->hash_table[i]))
+ return 0;
+ return 1;
+}
+
+static void flow_cache_flush_per_cpu(void *data)
+{
+ struct flow_flush_info *info = data;
+ struct tasklet_struct *tasklet;
+
+ tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet;
+ tasklet->data = (unsigned long)info;
+ tasklet_schedule(tasklet);
+}
+
+void flow_cache_flush(struct net *net)
+{
+ struct flow_flush_info info;
+ cpumask_var_t mask;
+ int i, self;
+
+ /* Track which cpus need flushing to avoid disturbing all cores. */
+ if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+ return;
+ cpumask_clear(mask);
+
+ /* Don't want cpus going down or up during this. */
+ get_online_cpus();
+ mutex_lock(&net->xfrm.flow_flush_sem);
+ info.cache = &net->xfrm.flow_cache_global;
+ for_each_online_cpu(i)
+ if (!flow_cache_percpu_empty(info.cache, i))
+ cpumask_set_cpu(i, mask);
+ atomic_set(&info.cpuleft, cpumask_weight(mask));
+ if (atomic_read(&info.cpuleft) == 0)
+ goto done;
+
+ init_completion(&info.completion);
+
+ local_bh_disable();
+ self = cpumask_test_and_clear_cpu(smp_processor_id(), mask);
+ on_each_cpu_mask(mask, flow_cache_flush_per_cpu, &info, 0);
+ if (self)
+ flow_cache_flush_tasklet((unsigned long)&info);
+ local_bh_enable();
+
+ wait_for_completion(&info.completion);
+
+done:
+ mutex_unlock(&net->xfrm.flow_flush_sem);
+ put_online_cpus();
+ free_cpumask_var(mask);
+}
+
+static void flow_cache_flush_task(struct work_struct *work)
+{
+ struct netns_xfrm *xfrm = container_of(work, struct netns_xfrm,
+ flow_cache_flush_work);
+ struct net *net = container_of(xfrm, struct net, xfrm);
+
+ flow_cache_flush(net);
+}
+
+void flow_cache_flush_deferred(struct net *net)
+{
+ schedule_work(&net->xfrm.flow_cache_flush_work);
+}
+
+static int flow_cache_cpu_prepare(struct flow_cache *fc, int cpu)
+{
+ struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
+ size_t sz = sizeof(struct hlist_head) * flow_cache_hash_size(fc);
+
+ if (!fcp->hash_table) {
+ fcp->hash_table = kzalloc_node(sz, GFP_KERNEL, cpu_to_node(cpu));
+ if (!fcp->hash_table) {
+ pr_err("NET: failed to allocate flow cache sz %zu\n", sz);
+ return -ENOMEM;
+ }
+ fcp->hash_rnd_recalc = 1;
+ fcp->hash_count = 0;
+ tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
+ }
+ return 0;
+}
+
+static int flow_cache_cpu(struct notifier_block *nfb,
+ unsigned long action,
+ void *hcpu)
+{
+ struct flow_cache *fc = container_of(nfb, struct flow_cache,
+ hotcpu_notifier);
+ int res, cpu = (unsigned long) hcpu;
+ struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ res = flow_cache_cpu_prepare(fc, cpu);
+ if (res)
+ return notifier_from_errno(res);
+ break;
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ __flow_cache_shrink(fc, fcp, 0);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+int flow_cache_init(struct net *net)
+{
+ int i;
+ struct flow_cache *fc = &net->xfrm.flow_cache_global;
+
+ if (!flow_cachep)
+ flow_cachep = kmem_cache_create("flow_cache",
+ sizeof(struct flow_cache_entry),
+ 0, SLAB_PANIC, NULL);
+ spin_lock_init(&net->xfrm.flow_cache_gc_lock);
+ INIT_LIST_HEAD(&net->xfrm.flow_cache_gc_list);
+ INIT_WORK(&net->xfrm.flow_cache_gc_work, flow_cache_gc_task);
+ INIT_WORK(&net->xfrm.flow_cache_flush_work, flow_cache_flush_task);
+ mutex_init(&net->xfrm.flow_flush_sem);
+
+ fc->hash_shift = 10;
+ fc->low_watermark = 2 * flow_cache_hash_size(fc);
+ fc->high_watermark = 4 * flow_cache_hash_size(fc);
+
+ fc->percpu = alloc_percpu(struct flow_cache_percpu);
+ if (!fc->percpu)
+ return -ENOMEM;
+
+ cpu_notifier_register_begin();
+
+ for_each_online_cpu(i) {
+ if (flow_cache_cpu_prepare(fc, i))
+ goto err;
+ }
+ fc->hotcpu_notifier = (struct notifier_block){
+ .notifier_call = flow_cache_cpu,
+ };
+ __register_hotcpu_notifier(&fc->hotcpu_notifier);
+
+ cpu_notifier_register_done();
+
+ setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
+ (unsigned long) fc);
+ fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+ add_timer(&fc->rnd_timer);
+
+ return 0;
+
+err:
+ for_each_possible_cpu(i) {
+ struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
+ kfree(fcp->hash_table);
+ fcp->hash_table = NULL;
+ }
+
+ cpu_notifier_register_done();
+
+ free_percpu(fc->percpu);
+ fc->percpu = NULL;
+
+ return -ENOMEM;
+}
+EXPORT_SYMBOL(flow_cache_init);
+
+void flow_cache_fini(struct net *net)
+{
+ int i;
+ struct flow_cache *fc = &net->xfrm.flow_cache_global;
+
+ del_timer_sync(&fc->rnd_timer);
+ unregister_hotcpu_notifier(&fc->hotcpu_notifier);
+
+ for_each_possible_cpu(i) {
+ struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
+ kfree(fcp->hash_table);
+ fcp->hash_table = NULL;
+ }
+
+ free_percpu(fc->percpu);
+ fc->percpu = NULL;
+}
+EXPORT_SYMBOL(flow_cache_fini);
Code Review / kvmfornfv.git / blobdiff