From: Tejun Heo <tj@kernel.org>
Date: Wed, 14 Aug 2013 00:22:50 +0000 (-0400)
Subject: cgroup: move cgroup->subsys[] assignment to online_css()
X-Git-Tag: v3.12-rc1~173^2~17
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ae7f164a09408bf21ab3c82a9e80a3ff37aa9e3e;p=pandora-kernel.git

cgroup: move cgroup->subsys[] assignment to online_css()

Currently, css (cgroup_subsys_state) lifetime is tied to that of the
associated cgroup.  With the planned unified hierarchy, css's will be
dynamically created and destroyed within the lifetime of a cgroup.  To
enable such usages, css's will be individually RCU protected instead
of being tied to the cgroup.

In preparation, this patch moves cgroup->subsys[] assignment from
init_css() to online_css().  As this means that a newly initialized
css should be remembered separately and that cgroup_css() returns NULL
between init and online, cgroup_create() is updated so that it stores
newly created css's in a local array css_ar[] and
cgroup_init/load_subsys() are updated to use local variable @css
instead of using cgroup_css().  This change also slightly simplifies
error path of cgroup_create().

While this patch changes when cgroup->subsys[] is initialized, this
change isn't visible to subsystems or userland.

v2: This patch wasn't updated accordingly after the previous "cgroup:
    reorganize css init / exit paths" was updated leading to missing a
    css_ar[] conversion in cgroup_create() and thus boot failure.  Fix
    it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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