[Patch] Add smp_mb__after_clear_bit() to unlock_kiocb()

[Zach Brown <zach.brown@oracle.com>]

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().

Please apply.

Signed-off-by: Zach Brown <zach.brown@oracle.com>

Index: 2.6.13-git12-mb-lock-kiocb/fs/aio.c
===================================================================
--- 2.6.13-git12-mb-lock-kiocb.orig/fs/aio.c
+++ 2.6.13-git12-mb-lock-kiocb/fs/aio.c
@@ -562,6 +562,7 @@ static inline void lock_kiocb(struct kio
 static inline void unlock_kiocb(struct kiocb *iocb)
 {
 	kiocbClearLocked(iocb);
+	smp_mb__after_clear_bit();
 	wake_up_bit(&iocb->ki_flags, KIF_LOCKED);
 }
 
  Signed-off-by: Zach Brown <zach.brown@oracle.com>

 aio.c |    1 +
 1 files changed, 1 insertion(+)
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