net: net_cls: move cgroupfs classid handling into core

Zefan Li requested [1] to perform the following cleanup/refactoring:

- Split cgroupfs classid handling into net core to better express a
  possible more generic use.

- Disable module support for cgroupfs bits as the majority of other
  cgroupfs subsystems do not have that, and seems to be not wished
  from cgroup side. Zefan probably might want to follow-up for netprio
  later on.

- By this, code can be further reduced which previously took care of
  functionality built when compiled as module.

cgroupfs bits are being placed under net/core/netclassid_cgroup.c, so
that we are consistent with {netclassid,netprio}_cgroup naming that is
under net/core/ as suggested by Zefan.

No change in functionality, but only code refactoring that is being
done here.

 [1] http://patchwork.ozlabs.org/patch/304825/

Suggested-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: cgroups@vger.kernel.org
Acked-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 13 insertions, 29 deletions

diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index b613ffd402d1..58bf94de4b8e 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -31,7 +31,7 @@ SUBSYS(devices)
 SUBSYS(freezer)
 #endif
 
-#if IS_SUBSYS_ENABLED(CONFIG_NET_CLS_CGROUP)
+#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_NET_CLASSID)
 SUBSYS(net_cls)
 #endif
 
diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h
index 33d03b648646..9cf2d5ef38d9 100644
--- a/include/net/cls_cgroup.h
+++ b/include/net/cls_cgroup.h
@@ -16,17 +16,16 @@
 #include <linux/cgroup.h>
 #include <linux/hardirq.h>
 #include <linux/rcupdate.h>
+#include <net/sock.h>
 
-#if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
-struct cgroup_cls_state
-{
+#ifdef CONFIG_CGROUP_NET_CLASSID
+struct cgroup_cls_state {
         struct cgroup_subsys_state css;
         u32 classid;
 };
 
-void sock_update_classid(struct sock *sk);
+struct cgroup_cls_state *task_cls_state(struct task_struct *p);
 
-#if IS_BUILTIN(CONFIG_NET_CLS_CGROUP)
 static inline u32 task_cls_classid(struct task_struct *p)
 {
         u32 classid;
@@ -41,33 +40,18 @@ static inline u32 task_cls_classid(struct task_struct *p)
 
         return classid;
 }
-#elif IS_MODULE(CONFIG_NET_CLS_CGROUP)
-static inline u32 task_cls_classid(struct task_struct *p)
-{
-        struct cgroup_subsys_state *css;
-        u32 classid = 0;
-
-        if (in_interrupt())
-                return 0;
-
-        rcu_read_lock();
-        css = task_css(p, net_cls_subsys_id);
-        if (css)
-                classid = container_of(css,
-                                       struct cgroup_cls_state, css)->classid;
-        rcu_read_unlock();
 
-        return classid;
-}
-#endif
-#else /* !CGROUP_NET_CLS_CGROUP */
 static inline void sock_update_classid(struct sock *sk)
 {
-}
+        u32 classid;
 
-static inline u32 task_cls_classid(struct task_struct *p)
+        classid = task_cls_classid(current);
+        if (classid != sk->sk_classid)
+                sk->sk_classid = classid;
+}
+#else /* !CONFIG_CGROUP_NET_CLASSID */
+static inline void sock_update_classid(struct sock *sk)
 {
-        return 0;
 }
-#endif /* CGROUP_NET_CLS_CGROUP */
+#endif /* CONFIG_CGROUP_NET_CLASSID */
 #endif  /* _NET_CLS_CGROUP_H */