Merge tag 'kbuild-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy...

[linux.git] / kernel / sched / wait.c

diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index c1e566a114ca64d5ef4d27a7db41c2d66f8039c0..ba059fbfc53a3dd4bdef4cc3e90a6ea97f6dd167 100644 (file)
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -169,7 +169,6 @@ EXPORT_SYMBOL_GPL(__wake_up_locked_key_bookmark);
  * __wake_up_sync_key - wake up threads blocked on a waitqueue.
  * @wq_head: the waitqueue
  * @mode: which threads
- * @nr_exclusive: how many wake-one or wake-many threads to wake up
  * @key: opaque value to be passed to wakeup targets
  *
  * The sync wakeup differs that the waker knows that it will schedule
@@ -183,26 +182,44 @@ EXPORT_SYMBOL_GPL(__wake_up_locked_key_bookmark);
  * accessing the task state.
  */
 void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode,
-                       int nr_exclusive, void *key)
+                       void *key)
 {
-       int wake_flags = 1; /* XXX WF_SYNC */
-
        if (unlikely(!wq_head))
                return;
 
-       if (unlikely(nr_exclusive != 1))
-               wake_flags = 0;
-
-       __wake_up_common_lock(wq_head, mode, nr_exclusive, wake_flags, key);
+       __wake_up_common_lock(wq_head, mode, 1, WF_SYNC, key);
 }
 EXPORT_SYMBOL_GPL(__wake_up_sync_key);
 
+/**
+ * __wake_up_locked_sync_key - wake up a thread blocked on a locked waitqueue.
+ * @wq_head: the waitqueue
+ * @mode: which threads
+ * @key: opaque value to be passed to wakeup targets
+ *
+ * The sync wakeup differs in that the waker knows that it will schedule
+ * away soon, so while the target thread will be woken up, it will not
+ * be migrated to another CPU - ie. the two threads are 'synchronized'
+ * with each other. This can prevent needless bouncing between CPUs.
+ *
+ * On UP it can prevent extra preemption.
+ *
+ * If this function wakes up a task, it executes a full memory barrier before
+ * accessing the task state.
+ */
+void __wake_up_locked_sync_key(struct wait_queue_head *wq_head,
+                              unsigned int mode, void *key)
+{
+        __wake_up_common(wq_head, mode, 1, WF_SYNC, key, NULL);
+}
+EXPORT_SYMBOL_GPL(__wake_up_locked_sync_key);
+
 /*
  * __wake_up_sync - see __wake_up_sync_key()
  */
-void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode, int nr_exclusive)
+void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode)
 {
-       __wake_up_sync_key(wq_head, mode, nr_exclusive, NULL);
+       __wake_up_sync_key(wq_head, mode, NULL);
 }
 EXPORT_SYMBOL_GPL(__wake_up_sync);     /* For internal use only */