device_cgroup: don't grab mutex in rcu callback
device_cgroup: don't grab mutex in rcu callback

Commit 103a197c0c4e ("security/device_cgroup: lock assert fails in
dev_exception_clean()") grabs devcgroup_mutex to fix assert failure, but
a mutex can't be grabbed in rcu callback.  Since there shouldn't be any
other references when css_free is called, mutex isn't needed for list
cleanup in devcgroup_css_free().

Signed-off-by: Jerry Snitselaar <644a8fb9a239a96aabccc22c5424d4338ad8defe@oracle.com>
Acked-by: Tejun Heo <546b05909706652891a87f7bfe385ae147f61f91@kernel.org>
Acked-by: Aristeu Rozanski <78e305742ac743ecf22d8139502576ac8709e0ad@redhat.com>
Cc: James Morris <bb9ce606a3116cc7a99739bd8e2dd57a2d5b69c1@oracle.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas