From: Jens Axboe <jens.axboe@oracle.com>
Date: Sat, 26 Sep 2009 15:31:32 +0000 (+0200)
Subject: wait: add wait_bit_cleared() helper
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=38d25eaa96ea02ec6b83e1165bc246657fd89eda;p=linux-block.git

wait: add wait_bit_cleared() helper

Check whether we got woken because our bit cleared or not.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

diff --git a/fs/aio.c b/fs/aio.c
index 36ee51a6d761..961f62a32109 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1533,8 +1533,7 @@ static int aio_wake_function(wait_queue_t *wait, unsigned mode,
 		= container_of(wait, struct wait_bit_queue, wait);
 	struct kiocb *iocb = container_of(wb, struct kiocb, ki_wq);
 
-	if (wb->key.flags != key->flags || wb->key.bit_nr != key->bit_nr ||
-			test_bit(key->bit_nr, key->flags))
+	if (!wait_bit_cleared(wb, key))
 		return 0;
 
 	list_del_init(&wait->task_list);
diff --git a/include/linux/wait.h b/include/linux/wait.h
index d6a073f3c3e0..586198803c0d 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -457,6 +457,16 @@ void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 
+static inline int wait_bit_cleared(struct wait_bit_queue *wb,
+				   struct wait_bit_key *key)
+{
+	if (wb->key.flags != key->flags || wb->key.bit_nr != key->bit_nr ||
+	    test_bit(key->bit_nr, key->flags))
+		return 0;
+
+	return 1;
+}
+
 #define DEFINE_WAIT_FUNC(name, function)				\
 	wait_queue_t name = {						\
 		.private	= current,				\
diff --git a/kernel/wait.c b/kernel/wait.c
index ca0b832d5ff3..1c95aa386edc 100644
--- a/kernel/wait.c
+++ b/kernel/wait.c
@@ -178,12 +178,10 @@ int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *arg)
 	struct wait_bit_queue *wait_bit
 		= container_of(wait, struct wait_bit_queue, wait);
 
-	if (wait_bit->key.flags != key->flags ||
-			wait_bit->key.bit_nr != key->bit_nr ||
-			test_bit(key->bit_nr, key->flags))
+	if (!wait_bit_cleared(wait_bit, key))
 		return 0;
-	else
-		return autoremove_wake_function(wait, mode, sync, key);
+
+	return autoremove_wake_function(wait, mode, sync, key);
 }
 EXPORT_SYMBOL(wake_bit_function);