4.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: Bart Van Assche <[email protected]> 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 <[email protected]> Cc: Tejun Heo <[email protected]> Signed-off-by: Tejun Heo <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- block/blk-cgroup.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1340,10 +1340,8 @@ 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;
