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>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 25247a8..ad1b9be 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4370,8 +4370,7 @@
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;
}