cgroup: pass around cgroup_subsys_state instead of cgroup in file methods

cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup.
Please see the previous commit which converts the subsystem methods
for rationale.

This patch converts all cftype file operations to take @css instead of
@cgroup.  cftypes for the cgroup core files don't have their subsytem
pointer set.  These will automatically use the dummy_css added by the
previous patch and can be converted the same way.

Most subsystem conversions are straight forwards but there are some
interesting ones.

* freezer: update_if_frozen() is also converted to take @css instead
  of @cgroup for consistency.  This will make the code look simpler
  too once iterators are converted to use css.

* memory/vmpressure: mem_cgroup_from_css() needs to be exported to
  vmpressure while mem_cgroup_from_cont() can be made static.
  Updated accordingly.

* cpu: cgroup_tg() doesn't have any user left.  Removed.

* cpuacct: cgroup_ca() doesn't have any user left.  Removed.

* hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
  Removed.

* net_cls: cgrp_cls_state() doesn't have any user left.  Removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 15 insertions, 21 deletions

diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 8d095b4c2f6f..e00f60e5baea 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -168,15 +168,14 @@ static void cgrp_css_free(struct cgroup_subsys_state *css)
         kfree(css);
 }
 
-static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
+static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft)
 {
-        return cgrp->id;
+        return css->cgroup->id;
 }
 
-static int read_priomap(struct cgroup *cont, struct cftype *cft,
+static int read_priomap(struct cgroup_subsys_state *css, struct cftype *cft,
                         struct cgroup_map_cb *cb)
 {
-        struct cgroup_subsys_state *css = cgroup_css(cont, net_prio_subsys_id);
         struct net_device *dev;
 
         rcu_read_lock();
@@ -186,10 +185,9 @@ static int read_priomap(struct cgroup *cont, struct cftype *cft,
         return 0;
 }
 
-static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
+static int write_priomap(struct cgroup_subsys_state *css, struct cftype *cft,
                          const char *buffer)
 {
-        struct cgroup_subsys_state *css = cgroup_css(cgrp, net_prio_subsys_id);
         char devname[IFNAMSIZ + 1];
         struct net_device *dev;
         u32 prio;
diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index da14436c1735..8a57d79b0b16 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -132,10 +132,10 @@ static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
         return 0;
 }
 
-static int tcp_cgroup_write(struct cgroup *cont, struct cftype *cft,
+static int tcp_cgroup_write(struct cgroup_subsys_state *css, struct cftype *cft,
                             const char *buffer)
 {
-        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+        struct mem_cgroup *memcg = mem_cgroup_from_css(css);
         unsigned long long val;
         int ret = 0;
 
@@ -180,9 +180,9 @@ static u64 tcp_read_usage(struct mem_cgroup *memcg)
         return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
 }
 
-static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)
+static u64 tcp_cgroup_read(struct cgroup_subsys_state *css, struct cftype *cft)
 {
-        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+        struct mem_cgroup *memcg = mem_cgroup_from_css(css);
         u64 val;
 
         switch (cft->private) {
@@ -202,13 +202,13 @@ static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)
         return val;
 }
 
-static int tcp_cgroup_reset(struct cgroup *cont, unsigned int event)
+static int tcp_cgroup_reset(struct cgroup_subsys_state *css, unsigned int event)
 {
         struct mem_cgroup *memcg;
         struct tcp_memcontrol *tcp;
         struct cg_proto *cg_proto;
 
-        memcg = mem_cgroup_from_cont(cont);
+        memcg = mem_cgroup_from_css(css);
         cg_proto = tcp_prot.proto_cgroup(memcg);
         if (!cg_proto)
                 return 0;
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index dc3983835893..8ea1184cec92 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -28,11 +28,6 @@ static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state
         return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
 }
 
-static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
-{
-        return css_cls_state(cgroup_css(cgrp, net_cls_subsys_id));
-}
-
 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
 {
         return css_cls_state(task_css(p, net_cls_subsys_id));
@@ -87,14 +82,15 @@ static void cgrp_attach(struct cgroup_subsys_state *css,
         }
 }
 
-static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
+static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
 {
-        return cgrp_cls_state(cgrp)->classid;
+        return css_cls_state(css)->classid;
 }
 
-static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
+static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
+                         u64 value)
 {
-        cgrp_cls_state(cgrp)->classid = (u32) value;
+        css_cls_state(css)->classid = (u32) value;
         return 0;
 }