From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH cgroup/for-3.12 1/2] cgroup: fix cgroup_write_event_control() Date: Thu, 15 Aug 2013 11:40:32 -0400 Message-ID: <20130815154032.GE14606@htj.dyndns.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:subject:message-id:mime-version:content-type :content-disposition:user-agent; bh=uHOD/En9kqywCsWUGzPkahD/JuU2M7x4iXaQoyW/CqI=; b=WmWwEp+AeKo/ppB+1/bhyX/tSimmDEllGeUHVY463BYzA/8A+CSr3Aen7S9XErX3fZ xolZmIxX3uaYkARvxucDLpGq4LD1X3REILMAAVc2xhmt+2t4Tt+EkP+WhRKJKNcj/9Jv 6iRvyGGcKRSauBZcIaOuHV0xh1o7RRPoNeH4/RV4VpEXtiYp3Q6JCL8k3rQNknSvehca 3w0UPL+HfUOVbkxGDcDlE97SQFgrHaZm4ICgttazMdiigJFhRIl/lm19I27MDhXhzCDn ys/8AjcGor1Fv4vRim7saAv2k/Gpk+KBKbxprD5dZPlWf7ieUc+JvXt17qy2eF8qEfCZ 53iw== Content-Disposition: inline Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Li Zefan , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org >From 994a762080e4b136171c82ac78f7d7bbf17a451d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 14 Aug 2013 23:38:21 -0400 81eeaf0411 ("cgroup: make cftype->[un]register_event() deal with cgroup_subsys_state inst ead of cgroup") updated the cftype event methods to take @css (cgroup_subsys_state) instead of @cgroup; however, it incorrectly used @css passed to cgroup_write_event_control(), which the dummy_css for the cgroup as the file is a cgroup core file. This leads to oops on event registration. Fix it by using the css matching the event target file. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 66d0107..ef93bfd 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4044,10 +4044,10 @@ static void cgroup_event_ptable_queue_proc(struct file *file, * Input must be in format ' '. * Interpretation of args is defined by control file implementation. */ -static int cgroup_write_event_control(struct cgroup_subsys_state *css, +static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css, struct cftype *cft, const char *buffer) { - struct cgroup *cgrp = css->cgroup; + struct cgroup *cgrp = dummy_css->cgroup; struct cgroup_event *event; struct cgroup *cgrp_cfile; unsigned int efd, cfd; @@ -4069,7 +4069,7 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css, event = kzalloc(sizeof(*event), GFP_KERNEL); if (!event) return -ENOMEM; - event->css = css; + INIT_LIST_HEAD(&event->list); init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); init_waitqueue_func_entry(&event->wait, cgroup_event_wake); @@ -4105,6 +4105,18 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css, goto out_put_cfile; } + /* determine the css of @cfile and associate @event with it */ + rcu_read_lock(); + + ret = -EINVAL; + event->css = cgroup_css(cgrp, event->cft->ss); + if (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. @@ -4120,7 +4132,7 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css, goto out_put_cfile; } - ret = event->cft->register_event(css, event->cft, + ret = event->cft->register_event(event->css, event->cft, event->eventfd, buffer); if (ret) goto out_put_cfile; -- 1.8.3.1