netprio_cgroup: use cgroup->id instead of cgroup_netprio_state->prioidx

With priomap expansion no longer depending on knowing max id
allocated, netprio_cgroup can use cgroup->id insted of cs->prioidx.
Drop prioidx alloc/free logic and convert all uses to cgroup->id.

* In cgrp_css_alloc(), parent->id test is moved above @cs allocation
  to simplify error path.

* In cgrp_css_free(), @cs assignment is made initialization.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Tested-and-Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 7 deletions

diff --git a/include/net/netprio_cgroup.h b/include/net/netprio_cgroup.h
index 2760f4f4ae9b..1d04b6f0fbd4 100644
--- a/include/net/netprio_cgroup.h
+++ b/include/net/netprio_cgroup.h
@@ -27,7 +27,6 @@ struct netprio_map {
 
 struct cgroup_netprio_state {
         struct cgroup_subsys_state css;
-        u32 prioidx;
 };
 
 extern void sock_update_netprioidx(struct sock *sk, struct task_struct *task);
@@ -36,13 +35,12 @@ extern void sock_update_netprioidx(struct sock *sk, struct task_struct *task);
 
 static inline u32 task_netprioidx(struct task_struct *p)
 {
-        struct cgroup_netprio_state *state;
+        struct cgroup_subsys_state *css;
         u32 idx;
 
         rcu_read_lock();
-        state = container_of(task_subsys_state(p, net_prio_subsys_id),
-                             struct cgroup_netprio_state, css);
-        idx = state->prioidx;
+        css = task_subsys_state(p, net_prio_subsys_id);
+        idx = css->cgroup->id;
         rcu_read_unlock();
         return idx;
 }
@@ -57,8 +55,7 @@ static inline u32 task_netprioidx(struct task_struct *p)
         rcu_read_lock();
         css = task_subsys_state(p, net_prio_subsys_id);
         if (css)
-                idx = container_of(css,
-                                   struct cgroup_netprio_state, css)->prioidx;
+                idx = css->cgroup->id;
         rcu_read_unlock();
         return idx;
 }