cgroup: make cftype->[un]register_event() deal with cgroup_subsys_state instead of cgroup

cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle.  This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.

cftype->[un]register_event() is among the remaining couple interfaces
which still use struct cgroup.  Convert it to cgroup_subsys_state.
The conversion is mostly mechanical and removes the last users of
mem_cgroup_from_cont() and cg_to_vmpressure(), which are removed.

v2: indentation update as suggested by Li Zefan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>

1 files changed, 8 insertions, 13 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 95106a993777..2885e3e85047 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1034,11 +1034,6 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
 		preempt_enable();
 }
 
-static inline struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
-{
-	return mem_cgroup_from_css(cgroup_css(cont, mem_cgroup_subsys_id));
-}
-
 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 {
 	/*
@@ -5620,10 +5615,10 @@ static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
 		mem_cgroup_oom_notify_cb(iter);
 }
 
-static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
+static int mem_cgroup_usage_register_event(struct cgroup_subsys_state *css,
 	struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup_thresholds *thresholds;
 	struct mem_cgroup_threshold_ary *new;
 	enum res_type type = MEMFILE_TYPE(cft->private);
@@ -5703,10 +5698,10 @@ unlock:
 	return ret;
 }
 
-static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
+static void mem_cgroup_usage_unregister_event(struct cgroup_subsys_state *css,
 	struct cftype *cft, struct eventfd_ctx *eventfd)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup_thresholds *thresholds;
 	struct mem_cgroup_threshold_ary *new;
 	enum res_type type = MEMFILE_TYPE(cft->private);
@@ -5782,10 +5777,10 @@ unlock:
 	mutex_unlock(&memcg->thresholds_lock);
 }
 
-static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
+static int mem_cgroup_oom_register_event(struct cgroup_subsys_state *css,
 	struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup_eventfd_list *event;
 	enum res_type type = MEMFILE_TYPE(cft->private);
 
@@ -5807,10 +5802,10 @@ static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
 	return 0;
 }
 
-static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
+static void mem_cgroup_oom_unregister_event(struct cgroup_subsys_state *css,
 	struct cftype *cft, struct eventfd_ctx *eventfd)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 	struct mem_cgroup_eventfd_list *ev, *tmp;
 	enum res_type type = MEMFILE_TYPE(cft->private);