| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 081/112] blkcg: Unlock blkcg_pol_mutex only once when cpd == NULL | Date | Wed, 26 Oct 2016 14:23:04 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Bart Van Assche <bart.vanassche@sandisk.com>
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@sandisk.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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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