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cgroup: make cgroup_write_event_control() use css_from_dir() instead of __d_cgrp()

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cgroup_event will be moved to its only user - memcg.  Replace
__d_cgrp() usage with css_from_dir(), which is already exported.  This
also simplifies the code a bit.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
This commit is contained in:
Tejun Heo 2013-08-26 18:40:56 -04:00
parent 7941cb027d
commit 7c918cbbd8
1 changed files with 5 additions and 13 deletions
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18
kernel/cgroup.c
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@ -4041,7 +4041,7 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
{
struct cgroup *cgrp = dummy_css->cgroup;
struct cgroup_event *event;
struct cgroup *cgrp_cfile;
struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
struct file *efile;
struct file *cfile;
@ -4103,7 +4103,8 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
}
/*
* Determine the css of @cfile and associate @event with it.
* Determine the css of @cfile, verify it belongs to the same
* cgroup as cgroup.event_control, and associate @event with it.
* Remaining events are automatically removed on cgroup destruction
* but the removal is asynchronous, so take an extra ref.
*/
@ -4111,23 +4112,14 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
ret = -EINVAL;
event->css = cgroup_css(cgrp, event->cft->ss);
if (event->css && css_tryget(event->css))
cfile_css = css_from_dir(cfile->f_dentry->d_parent, event->cft->ss);
if (event->css && event->css == cfile_css && css_tryget(event->css))
ret = 0;
rcu_read_unlock();
if (ret)
goto out_put_cfile;
/*
* The file to be monitored must be in the same cgroup as
* cgroup.event_control is.
*/
cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
if (cgrp_cfile != cgrp) {
ret = -EINVAL;
goto out_put_css;
}
if (!event->cft->register_event || !event->cft->unregister_event) {
ret = -EINVAL;
goto out_put_css;