X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fsched.c;h=9a1ddb84e26d56e7d6b283daab1edbad20ae2042;hb=4309e092421e08f411830b2675bc1538a9b90e9b;hp=040807196b33c09bbc9fed95fe3522b78117e38d;hpb=55cd53404c5cc5fd94708232e3b4aa4a9388917b;p=linux-2.6

diff --git a/kernel/sched.c b/kernel/sched.c
index 040807196b..9a1ddb84e2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -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)
 {