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authorShaohua Li <shli@kernel.org>2014-04-15 09:12:54 +0800
committerNeilBrown <neilb@suse.de>2014-04-17 17:05:28 +1000
commitc7a6d35e463caacab08ca0333bdec5b8bdce8bbb (patch)
treebf4abac968402f11ba3d26e238ab62173f2bb23a /drivers/md
parente240c1839d11152b0355442f8ac6d2d2d921be36 (diff)
downloadlinux-c7a6d35e463caacab08ca0333bdec5b8bdce8bbb.tar.gz
raid5: fix a race of stripe count check
I hit another BUG_ON with e240c1839d11152b0355442. In __get_priority_stripe(),
stripe count equals to 0 initially. Between atomic_inc and BUG_ON,
get_active_stripe() finds the stripe. So the stripe count isn't 1 any more.

V2: keeps the BUG_ON suggested by Neil.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/raid5.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 25247a852912..ad1b9bea446e 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4370,8 +4370,7 @@ static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
 		sh->group = NULL;
 	}
 	list_del_init(&sh->lru);
-	atomic_inc(&sh->count);
-	BUG_ON(atomic_read(&sh->count) != 1);
+	BUG_ON(atomic_inc_return(&sh->count) != 1);
 	return sh;
 }