Commits
Tejun Heo committed 069df3b7aeb
cgroup: remove cgroup_pidlist->rwsem cgroup_pidlist locking is needlessly complicated. It has outer cgroup->pidlist_mutex to protect the list of pidlists associated with a cgroup and then each pidlist has rwsem to synchronize updates and reads. Given that the only read access is from seq_file operations which are always invoked back-to-back, the rwsem is a giant overkill. All it does is adding unnecessary complexity. This patch removes cgroup_pidlist->rwsem and protects all accesses to pidlists belonging to a cgroup with cgroup->pidlist_mutex. pidlist->rwsem locking is removed if it's nested inside cgroup->pidlist_mutex; otherwise, it's replaced with cgroup->pidlist_mutex locking. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>