4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
commit bbb427e342495df1cda10051d0566388697499c0 upstream.
Unlocking a mutex twice is wrong. Hence modify blkcg_policy_register()
such that blkcg_pol_mutex is unlocked once if cpd == NULL. This patch
avoids that smatch reports the following error:
block/blk-cgroup.c:1378: blkcg_policy_register() error: double unlock 'mutex:&blkcg_pol_mutex'
Fixes: 06b285bd1125 ("blkcg: fix blkcg_policy_data allocation bug")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/blk-cgroup.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1331,10 +1331,8 @@ int blkcg_policy_register(struct blkcg_p
struct blkcg_policy_data *cpd;
cpd = pol->cpd_alloc_fn(GFP_KERNEL);
- if (!cpd) {
- mutex_unlock(&blkcg_pol_mutex);
+ if (!cpd)
goto err_free_cpds;
- }
blkcg->cpd[pol->plid] = cpd;
cpd->blkcg = blkcg;
--
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