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authorTejun Heo <tj@kernel.org>2013-08-15 11:43:15 -0400
committerTejun Heo <tj@kernel.org>2013-08-19 09:56:34 -0400
commit6e6eab0efdf48fb2d8d7aee904d7740acb4661c6 (patch)
tree7805e157bdbe18844f650fa0a691cd8d1a6e1baf /kernel/cgroup.c
parent0bfb4aa67cef4982adc70590a31624d7b35a0bda (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>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c25
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;