Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / kernel / sched / wait-simple.c

diff --git a/kernel/kernel/sched/wait-simple.c b/kernel/kernel/sched/wait-simple.c
new file mode 100644 (file)
index 0000000..7dfa86d
--- /dev/null
+++ b/kernel/kernel/sched/wait-simple.c
@@ -0,0 +1,115 @@
+/*
+ * Simple waitqueues without fancy flags and callbacks
+ *
+ * (C) 2011 Thomas Gleixner <tglx@linutronix.de>
+ *
+ * Based on kernel/wait.c
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/wait-simple.h>
+
+/* Adds w to head->list. Must be called with head->lock locked. */
+static inline void __swait_enqueue(struct swait_head *head, struct swaiter *w)
+{
+       list_add(&w->node, &head->list);
+       /* We can't let the condition leak before the setting of head */
+       smp_mb();
+}
+
+/* Removes w from head->list. Must be called with head->lock locked. */
+static inline void __swait_dequeue(struct swaiter *w)
+{
+       list_del_init(&w->node);
+}
+
+void __init_swait_head(struct swait_head *head, struct lock_class_key *key)
+{
+       raw_spin_lock_init(&head->lock);
+       lockdep_set_class(&head->lock, key);
+       INIT_LIST_HEAD(&head->list);
+}
+EXPORT_SYMBOL(__init_swait_head);
+
+void swait_prepare_locked(struct swait_head *head, struct swaiter *w)
+{
+       w->task = current;
+       if (list_empty(&w->node))
+               __swait_enqueue(head, w);
+}
+
+void swait_prepare(struct swait_head *head, struct swaiter *w, int state)
+{
+       unsigned long flags;
+
+       raw_spin_lock_irqsave(&head->lock, flags);
+       swait_prepare_locked(head, w);
+       __set_current_state(state);
+       raw_spin_unlock_irqrestore(&head->lock, flags);
+}
+EXPORT_SYMBOL(swait_prepare);
+
+void swait_finish_locked(struct swait_head *head, struct swaiter *w)
+{
+       __set_current_state(TASK_RUNNING);
+       if (w->task)
+               __swait_dequeue(w);
+}
+
+void swait_finish(struct swait_head *head, struct swaiter *w)
+{
+       unsigned long flags;
+
+       __set_current_state(TASK_RUNNING);
+       if (w->task) {
+               raw_spin_lock_irqsave(&head->lock, flags);
+               __swait_dequeue(w);
+               raw_spin_unlock_irqrestore(&head->lock, flags);
+       }
+}
+EXPORT_SYMBOL(swait_finish);
+
+unsigned int
+__swait_wake_locked(struct swait_head *head, unsigned int state, unsigned int num)
+{
+       struct swaiter *curr, *next;
+       int woken = 0;
+
+       list_for_each_entry_safe(curr, next, &head->list, node) {
+               if (wake_up_state(curr->task, state)) {
+                       __swait_dequeue(curr);
+                       /*
+                        * The waiting task can free the waiter as
+                        * soon as curr->task = NULL is written,
+                        * without taking any locks. A memory barrier
+                        * is required here to prevent the following
+                        * store to curr->task from getting ahead of
+                        * the dequeue operation.
+                        */
+                       smp_wmb();
+                       curr->task = NULL;
+                       if (++woken == num)
+                               break;
+               }
+       }
+       return woken;
+}
+
+unsigned int
+__swait_wake(struct swait_head *head, unsigned int state, unsigned int num)
+{
+       unsigned long flags;
+       int woken;
+
+       if (!swaitqueue_active(head))
+               return 0;
+
+       raw_spin_lock_irqsave(&head->lock, flags);
+       woken = __swait_wake_locked(head, state, num);
+       raw_spin_unlock_irqrestore(&head->lock, flags);
+       return woken;
+}
+EXPORT_SYMBOL(__swait_wake);