From: Zach Brown <zach.brown@oracle.com>
Date: Sat, 17 Sep 2005 02:28:09 +0000 (-0700)
Subject: [PATCH] Add smp_mb__after_clear_bit() to unlock_kiocb()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=a464adeb7e8f1cd65ca911e20a7c02e452dc2c17;p=openwrt%2Fstaging%2Fblogic.git

[PATCH] Add smp_mb__after_clear_bit() to unlock_kiocb()

Add smp_mb__after_clear_bit() to unlock_kiocb()

AIO's use of wait_on_bit_lock()/wake_up_bit() forgot to add a barrier
between clearing its lock bit and calling wake_up_bit() so wake_up_bit()'s
unlocked waitqueue_active() can race.  This puts AIO's use in line with the
others and the comment above wake_up_bit().

Signed-off-by: Zach Brown <zach.brown@oracle.com>
Acked-by: Benjamin LaHaise <bcrl@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/fs/aio.c b/fs/aio.c
index 38f62680fd63..0e11e31dbb77 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -562,6 +562,7 @@ static inline void lock_kiocb(struct kiocb *iocb)
 static inline void unlock_kiocb(struct kiocb *iocb)
 {
 	kiocbClearLocked(iocb);
+	smp_mb__after_clear_bit();
 	wake_up_bit(&iocb->ki_flags, KIF_LOCKED);
 }