]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
cgroup: Remove task_lock() from cgroup_post_fork()
authorFrederic Weisbecker <fweisbec@gmail.com>
Fri, 23 Dec 2011 03:25:23 +0000 (04:25 +0100)
committerTejun Heo <tj@kernel.org>
Tue, 27 Dec 2011 17:05:20 +0000 (09:05 -0800)
commit7e3aa30ac8c904a706518b725c451bb486daaae9
tree1a6ad0678271d1cba5eba2fcafcbfa71b4e4c66d
parentc6ca57500c23d57a4ccec9874b6a3c99c297e1b5
cgroup: Remove task_lock() from cgroup_post_fork()

cgroup_post_fork() is protected between threadgroup_change_begin()
and threadgroup_change_end() against concurrent changes of the
child's css_set in cgroup_task_migrate(). Also the child can't
exit and call cgroup_exit() at this stage, this means it's css_set
can't be changed with init_css_set concurrently.

For these reasons, we don't need to hold task_lock() on the child
because it's css_set can only remain stable in this place.

Let's remove the lock there.

v2: Update comment to explain that we are safe against
cgroup_exit()

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Containers <containers@lists.linux-foundation.org>
Cc: Cgroups <cgroups@vger.kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Mandeep Singh Baines <msb@chromium.org>
kernel/cgroup.c