]> nv-tegra.nvidia Code Review - linux-2.6.git/blobdiff - kernel/sched.c
Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6.git] / kernel / sched.c
index 040807196b33c09bbc9fed95fe3522b78117e38d..9a1ddb84e26d56e7d6b283daab1edbad20ae2042 100644 (file)
@@ -4669,6 +4669,52 @@ int __sched wait_for_completion_killable(struct completion *x)
 }
 EXPORT_SYMBOL(wait_for_completion_killable);
 
+/**
+ *     try_wait_for_completion - try to decrement a completion without blocking
+ *     @x:     completion structure
+ *
+ *     Returns: 0 if a decrement cannot be done without blocking
+ *              1 if a decrement succeeded.
+ *
+ *     If a completion is being used as a counting completion,
+ *     attempt to decrement the counter without blocking. This
+ *     enables us to avoid waiting if the resource the completion
+ *     is protecting is not available.
+ */
+bool try_wait_for_completion(struct completion *x)
+{
+       int ret = 1;
+
+       spin_lock_irq(&x->wait.lock);
+       if (!x->done)
+               ret = 0;
+       else
+               x->done--;
+       spin_unlock_irq(&x->wait.lock);
+       return ret;
+}
+EXPORT_SYMBOL(try_wait_for_completion);
+
+/**
+ *     completion_done - Test to see if a completion has any waiters
+ *     @x:     completion structure
+ *
+ *     Returns: 0 if there are waiters (wait_for_completion() in progress)
+ *              1 if there are no waiters.
+ *
+ */
+bool completion_done(struct completion *x)
+{
+       int ret = 1;
+
+       spin_lock_irq(&x->wait.lock);
+       if (!x->done)
+               ret = 0;
+       spin_unlock_irq(&x->wait.lock);
+       return ret;
+}
+EXPORT_SYMBOL(completion_done);
+
 static long __sched
 sleep_on_common(wait_queue_head_t *q, int state, long timeout)
 {