memcg: cgroup_write_event_control() now knows @css is for memcg
@css for cgroup_write_event_control() is now always for memcg and the
target file should be a memcg file too. Drop code which assumes @css
is dummy_css and the target file may belong to different subsystems.
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>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 02dae32..d003681 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6056,10 +6056,10 @@
* 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 *dummy_css,
+static int cgroup_write_event_control(struct cgroup_subsys_state *css,
struct cftype *cft, const char *buffer)
{
- struct cgroup *cgrp = dummy_css->cgroup;
+ struct cgroup *cgrp = css->cgroup;
struct cgroup_event *event;
struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
@@ -6082,6 +6082,7 @@
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);
@@ -6117,23 +6118,17 @@
goto out_put_cfile;
}
- if (!event->cft->ss) {
- ret = -EBADF;
- goto out_put_cfile;
- }
-
/*
- * 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.
+ * Verify @cfile should belong to @css. Also, remaining events are
+ * automatically removed on cgroup destruction but the removal is
+ * asynchronous, so take an extra ref on @css.
*/
rcu_read_lock();
ret = -EINVAL;
- event->css = cgroup_css(cgrp, event->cft->ss);
- cfile_css = css_from_dir(cfile.file->f_dentry->d_parent, event->cft->ss);
- if (event->css && event->css == cfile_css && css_tryget(event->css))
+ cfile_css = css_from_dir(cfile.file->f_dentry->d_parent,
+ &mem_cgroup_subsys);
+ if (cfile_css == css && css_tryget(css))
ret = 0;
rcu_read_unlock();
@@ -6145,7 +6140,7 @@
goto out_put_css;
}
- ret = event->cft->register_event(event->css, event->cft,
+ ret = event->cft->register_event(css, event->cft,
event->eventfd, buffer);
if (ret)
goto out_put_css;
@@ -6162,7 +6157,7 @@
return 0;
out_put_css:
- css_put(event->css);
+ css_put(css);
out_put_cfile:
fdput(cfile);
out_put_eventfd: