From: Alex Elder <elder@inktank.com>
To: xfs@oss.sgi.com
Subject: [PATCH 2/2] xfs: another memory barrier before wake_up_bit()
Date: Mon, 04 Feb 2013 10:13:23 -0600 [thread overview]
Message-ID: <510FDE23.9050801@inktank.com> (raw)
In-Reply-To: <510FDDE5.4050103@inktank.com>
In xfs_inode_item_unpin() there is a call to wake_up_bit() following
an independent test for whether waiters should be awakened. This
requires a memory barrier in order to guarantee correct operation
(see the comment above wake_up_bit()).
Signed-off-by: Alex Elder <elder@inktank.com>
---
fs/xfs/xfs_inode_item.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index d041d47..a7cacf7 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -474,8 +474,10 @@ xfs_inode_item_unpin(
trace_xfs_inode_unpin(ip, _RET_IP_);
ASSERT(atomic_read(&ip->i_pincount) > 0);
- if (atomic_dec_and_test(&ip->i_pincount))
- wake_up_bit(&ip->i_flags, __XFS_IPINNED_BIT);
+ if (!atomic_dec_and_test(&ip->i_pincount))
+ return;
+ smp_mb();
+ wake_up_bit(&ip->i_flags, __XFS_IPINNED_BIT);
}
STATIC uint
--
1.7.9.5
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next prev parent reply other threads:[~2013-02-04 16:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-04 16:12 [PATCH 0/2] xfs: insert memory barriers before wake_up_bit() Alex Elder
2013-02-04 16:13 ` [PATCH 1/2] xfs: memory barrier " Alex Elder
2013-02-04 23:06 ` Dave Chinner
2013-02-05 1:35 ` Alex Elder
2013-02-07 15:44 ` Ben Myers
2013-02-04 16:13 ` Alex Elder [this message]
2013-02-04 23:26 ` [PATCH 2/2] xfs: another " Dave Chinner
2013-02-05 1:38 ` Alex Elder
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