[PATCH v0 0/5] cgroup: Assign subsystem IDs during compile time

From: Daniel Wagner <redacted>

Hi,

The patch #1 and #2 are there to be able to introduce (#3, #4) the 
jump labels in task_cls_classid() and task_netprioidx(). The jump
labels are needed to know when it is safe to access the controller. 
For example not safe means the module is not yet loaded.

All those patches are just preparation for the center piece (#5) 
of these series. This one will remove the dynamic subsystem ID
generation and falls back to compile time generated IDs. 

This is the first result from the discussion around on the
"cgroup cls & netprio 'cleanups'" patches.

This patches are against net-next

cheers,
daniel

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Gao feng <redacted>
Cc: Glauber Costa <redacted>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: John Fastabend <redacted>
Cc: Kamezawa Hiroyuki <redacted>
Cc: Li Zefan <redacted>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: netdev@vger.kernel.org
Cc: cgroups@vger.kernel.org

Daniel Wagner (5):
  cgroup: Use empty task_cls_classid() when !CONFIG_NET_CLS(_MODULE)
  cgroup: Move sock_update_classid() decleration to cls_cgroup.h
  cgroup: Protect access to task_cls_classid() when built as module
  cgroup: Protect access to task_netprioidx() when built as module
  cgroup: Assign subsystem IDs during compile time

 include/linux/cgroup.h        | 20 +++++++++++++-------
 include/linux/cgroup_subsys.h | 24 ++++++++++++------------
 include/net/cls_cgroup.h      | 42 +++++++++++++++++++++++++++++-------------
 include/net/netprio_cgroup.h  | 23 +++++++++++------------
 include/net/sock.h            |  8 --------
 kernel/cgroup.c               | 31 +++++++++----------------------
 net/core/netprio_cgroup.c     | 17 ++++++-----------
 net/core/sock.c               | 12 ++++++------
 net/sched/cls_cgroup.c        | 18 +++++-------------
 9 files changed, 91 insertions(+), 104 deletions(-)

-- 
1.7.12.rc1.16.g05a20c8

From: Daniel Wagner <redacted>

The only user of sock_update_classid() is net/socket.c which
happens to include cls_cgroup.h direclty.

Signed-off-by: Daniel Wagner <redacted>
Cc: Gao feng <redacted>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: John Fastabend <redacted>
Cc: Li Zefan <redacted>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: netdev@vger.kernel.org
Cc: cgroups@vger.kernel.org
---
 include/net/cls_cgroup.h | 8 ++++++++
 include/net/sock.h       | 8 --------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h
index e2fe2b9..401672c 100644
--- a/include/net/cls_cgroup.h
+++ b/include/net/cls_cgroup.h

@@ -24,6 +24,8 @@ struct cgroup_cls_state
 	u32 classid;
 };
 
+extern void sock_update_classid(struct sock *sk);
+
 #if IS_BUILTIN(CONFIG_NET_CLS_CGROUP)
 
 static inline u32 task_cls_classid(struct task_struct *p)

@@ -73,6 +75,12 @@ static inline u32 task_cls_classid(struct task_struct *p)
 
 #endif /* CONFIG_NET_CLS_CGROUP */
 
+#else /* !CONFIG_CGROUPS */
+
+static inline void sock_update_classid(struct sock *sk)
+{
+}
+
 #endif /* CONFIG_CGROURPS */
 
 #endif  /* _NET_CLS_CGROUP_H */

diff --git a/include/net/sock.h b/include/net/sock.h
index 72132ae..160a680 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h

@@ -1486,14 +1486,6 @@ extern void *sock_kmalloc(struct sock *sk, int size,
 extern void sock_kfree_s(struct sock *sk, void *mem, int size);
 extern void sk_send_sigurg(struct sock *sk);
 
-#ifdef CONFIG_CGROUPS
-extern void sock_update_classid(struct sock *sk);
-#else
-static inline void sock_update_classid(struct sock *sk)
-{
-}
-#endif
-
 /*
  * Functions to fill in entries in struct proto_ops when a protocol
  * does not implement a particular function.

-- 
1.7.12.rc1.16.g05a20c8

From: Daniel Wagner <redacted>

The module version of task_cls_classid() checks if net_cls_sbusys_id
is valid to indentify when it is okay to access the controller.

Instead relying on the subusys_id to be set, make it explicit
with a jump label.

Signed-off-by: Daniel Wagner <redacted>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gao feng <redacted>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: John Fastabend <redacted>
Cc: Li Zefan <redacted>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: netdev@vger.kernel.org
Cc: cgroups@vger.kernel.org
---
 include/net/cls_cgroup.h | 8 +++++++-
 net/core/sock.c          | 5 +++++
 net/sched/cls_cgroup.c   | 5 +++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h
index 401672c..5b91220 100644
--- a/include/net/cls_cgroup.h
+++ b/include/net/cls_cgroup.h

@@ -16,6 +16,7 @@
 #include <linux/cgroup.h>
 #include <linux/hardirq.h>
 #include <linux/rcupdate.h>
+#include <linux/jump_label.h>
 
 #ifdef CONFIG_CGROUPS
 struct cgroup_cls_state

@@ -24,6 +25,11 @@ struct cgroup_cls_state
 	u32 classid;
 };
 
+#if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
+extern struct static_key cgroup_cls_enabled;
+#define clscg_enabled static_key_false(&cgroup_cls_enabled)
+#endif
+
 extern void sock_update_classid(struct sock *sk);
 
 #if IS_BUILTIN(CONFIG_NET_CLS_CGROUP)

@@ -52,7 +58,7 @@ static inline u32 task_cls_classid(struct task_struct *p)
 	int id;
 	u32 classid = 0;
 
-	if (in_interrupt())
+	if (!clscg_enabled || in_interrupt())
 		return 0;
 
 	rcu_read_lock();

diff --git a/net/core/sock.c b/net/core/sock.c
index 8f67ced..8d3a400 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c

@@ -327,6 +327,11 @@ int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 EXPORT_SYMBOL(__sk_backlog_rcv);
 
 #if defined(CONFIG_CGROUPS)
+#if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
+struct static_key cgroup_cls_enabled = STATIC_KEY_INIT_FALSE;
+EXPORT_SYMBOL_GPL(cgroup_cls_enabled);
+#endif
+
 #if !defined(CONFIG_NET_CLS_CGROUP)
 int net_cls_subsys_id = -1;
 EXPORT_SYMBOL_GPL(net_cls_subsys_id);

diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index 7743ea8..f40086b 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c

@@ -44,12 +44,17 @@ static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
 
 	if (cgrp->parent)
 		cs->classid = cgrp_cls_state(cgrp->parent)->classid;
+	else if (!clscg_enabled)
+                static_key_slow_inc(&cgroup_cls_enabled);
 
 	return &cs->css;
 }
 
 static void cgrp_destroy(struct cgroup *cgrp)
 {
+	if (!cgrp->parent && clscg_enabled)
+                static_key_slow_dec(&cgroup_cls_enabled);
+
 	kfree(cgrp_cls_state(cgrp));
 }
 

-- 
1.7.12.rc1.16.g05a20c8