memcg: remove cgroup_event->cft

The only use of cgroup_event->cft is distinguishing "usage_in_bytes"
and "memsw.usgae_in_bytes" for mem_cgroup_usage_[un]register_event(),
which can be done by adding an explicit argument to the function and
implementing two wrappers so that the two cases can be distinguished
from the function alone.

Remove cgroup_event->cft and the related code including
[un]register_events() methods.

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>
Acked-by: Michal Hocko <mhocko@suse.cz>

1 files changed, 3 insertions, 11 deletions

diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index e0f62837c3f4..0f25a996d150 100644
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -279,7 +279,6 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
 /**
  * vmpressure_register_event() - Bind vmpressure notifications to an eventfd
  * @css:	css that is interested in vmpressure notifications
- * @cft:	cgroup control files handle
  * @eventfd:	eventfd context to link notifications with
  * @args:	event arguments (used to set up a pressure level threshold)
  *
@@ -289,13 +288,10 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
  * threshold (one of vmpressure_str_levels, i.e. "low", "medium", or
  * "critical").
  *
- * This function should not be used directly, just pass it to (struct
- * cftype).register_event, and then cgroup core will handle everything by
- * itself.
+ * To be used as memcg event method.
  */
 int vmpressure_register_event(struct cgroup_subsys_state *css,
-			      struct cftype *cft, struct eventfd_ctx *eventfd,
-			      const char *args)
+			      struct eventfd_ctx *eventfd, const char *args)
 {
 	struct vmpressure *vmpr = css_to_vmpressure(css);
 	struct vmpressure_event *ev;
@@ -326,19 +322,15 @@ int vmpressure_register_event(struct cgroup_subsys_state *css,
 /**
  * vmpressure_unregister_event() - Unbind eventfd from vmpressure
  * @css:	css handle
- * @cft:	cgroup control files handle
  * @eventfd:	eventfd context that was used to link vmpressure with the @cg
  *
  * This function does internal manipulations to detach the @eventfd from
  * the vmpressure notifications, and then frees internal resources
  * associated with the @eventfd (but the @eventfd itself is not freed).
  *
- * This function should not be used directly, just pass it to (struct
- * cftype).unregister_event, and then cgroup core will handle everything
- * by itself.
+ * To be used as memcg event method.
  */
 void vmpressure_unregister_event(struct cgroup_subsys_state *css,
-				 struct cftype *cft,
 				 struct eventfd_ctx *eventfd)
 {
 	struct vmpressure *vmpr = css_to_vmpressure(css);