1 files changed, 46 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index d601fb0406ca..95e6ad3c231d 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)
 {