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Message-Id: <1259158975-28499-2-git-send-email-swhiteho@redhat.com>
Date: Wed, 25 Nov 2009 14:22:26 +0000
From: Steven Whitehouse <swhiteho@...hat.com>
To: linux-kernel@...r.kernel.org, cluster-devel@...hat.com
Cc: Steven Whitehouse <swhiteho@...hat.com>
Subject: [PATCH 01/30] GFS2: Fix potential race in glock code
We need to be careful of the ordering between clearing the
GLF_LOCK bit and scheduling the workqueue.
Signed-off-by: Steven Whitehouse <swhiteho@...hat.com>
---
fs/gfs2/glock.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 8b674b1..a3f90ad 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -672,12 +672,17 @@ out:
return;
out_sched:
+ clear_bit(GLF_LOCK, &gl->gl_flags);
+ smp_mb__after_clear_bit();
gfs2_glock_hold(gl);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put_nolock(gl);
+ return;
+
out_unlock:
clear_bit(GLF_LOCK, &gl->gl_flags);
- goto out;
+ smp_mb__after_clear_bit();
+ return;
}
static void delete_work_func(struct work_struct *work)
@@ -1375,10 +1380,11 @@ static int gfs2_shrink_glock_memory(int nr, gfp_t gfp_mask)
handle_callback(gl, LM_ST_UNLOCKED, 0);
nr--;
}
+ clear_bit(GLF_LOCK, &gl->gl_flags);
+ smp_mb__after_clear_bit();
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put_nolock(gl);
spin_unlock(&gl->gl_spin);
- clear_bit(GLF_LOCK, &gl->gl_flags);
spin_lock(&lru_lock);
continue;
}
--
1.6.2.5
--
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