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Commit 7c918cbb authored by Tejun Heo's avatar Tejun Heo
Browse files

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



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: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
parent 7941cb02

kernel/cgroup.c

+5 −13
Original line number Diff line number Diff line
@@ -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;