diff options
| author | Tejun Heo <tj@kernel.org> | 2013-08-15 11:43:15 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-08-19 09:56:34 -0400 |
| commit | 6e6eab0efdf48fb2d8d7aee904d7740acb4661c6 (patch) | |
| tree | 7805e157bdbe18844f650fa0a691cd8d1a6e1baf | |
| parent | 0bfb4aa67cef4982adc70590a31624d7b35a0bda (diff) | |
cgroup: fix cgroup_write_event_control()
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. Note that
cgroup_write_event_control() now disallows cgroup core files from
being event sources. This is for simplicity and doesn't matter as
cgroup_event will be moved and made specific to memcg.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
| -rw-r--r-- | kernel/cgroup.c | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 896e035eb6e4..ef43e3f453ef 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4040,10 +4040,10 @@ static void cgroup_event_ptable_queue_proc(struct file *file, * Input must be in format '<event_fd> <control_fd> <args>'. * 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; @@ -4065,7 +4065,7 @@ 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); @@ -4101,6 +4101,23 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css, goto out_put_cfile; } + if (!event->cft->ss) { + ret = -EBADF; + 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->subsys_id); + 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. @@ -4116,7 +4133,7 @@ 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; |