[dm-6.4,v2,5/9] dm bufio: use waitqueue_active in __free_buffer_wake

Commit Message

Mike Snitzer March 24, 2023, 5:56 p.m. UTC

From: Mikulas Patocka <[e-mail]>

Save one spinlock by using waitqueue_active. We hold the bufio lock at
this place, so no one can add entries to the waitqueue at this point.

Signed-off-by: Mikulas Patocka <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>
---
 drivers/md/dm-bufio.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Patch

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 929685011e02..b638ddd161b4 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1669,7 +1669,12 @@  static void __free_buffer_wake(struct dm_buffer *b)
 		c->need_reserved_buffers--;
 	}
 
-	wake_up(&c->free_buffer_wait);
+	/*
+	 * We hold the bufio lock here, so no one can add entries to the
+	 * wait queue anyway.
+	 */
+	if (unlikely(waitqueue_active(&c->free_buffer_wait)))
+		wake_up(&c->free_buffer_wait);
 }
 
 static enum evict_result cleaned(struct dm_buffer *b, void *context)