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authorSteven Whitehouse <swhiteho@redhat.com>2009-09-22 10:56:16 +0100
committerSteven Whitehouse <swhiteho@redhat.com>2009-12-03 11:42:25 +0000
commit7e71c55ee73988d0cb61045660b899eaac23bf8f (patch)
treeef96dc44cd067cc758a8df0408ba36818c9ebc35
parent22763c5cf3690a681551162c15d34d935308c8d7 (diff)
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@redhat.com>
-rw-r--r--fs/gfs2/glock.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 8b674b1f3a55..a3f90ad2af80 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;
}