Re: [PATCH v0 3/4] cgroup: net_cls: Pass in task to sock_update_classid()

On 17.10.2012 15:37, Eric Dumazet wrote:

On Wed, 2012-10-17 at 15:04 +0200, Daniel Wagner wrote:

quoted

From: Daniel Wagner <redacted>

sock_update_classid() assumes that the update operation always are
applied on the current task. sock_update_classid() needs to know on
which tasks to work on in order to be able to migrate task between
cgroups using the struct cgroup_subsys attach() callback.

...

quoted

-extern void sock_update_classid(struct sock *sk);
+extern void sock_update_classid(struct sock *sk, struct task_struct *task);

  #if IS_BUILTIN(CONFIG_NET_CLS_CGROUP)
  static inline u32 task_cls_classid(struct task_struct *p)

diff --git a/net/core/sock.c b/net/core/sock.c
index 8a146cf..68c2f3b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c

@@ -1214,12 +1214,12 @@ static void sk_prot_free(struct proto *prot, struct sock *sk)

  #ifdef CONFIG_CGROUPS
  #if IS_ENABLED(CONFIG_NET_CLS_CGROUP)
-void sock_update_classid(struct sock *sk)
+void sock_update_classid(struct sock *sk, struct task_struct *task)
  {
  	u32 classid;

  	rcu_read_lock();  /* doing current task, which cannot vanish. */
-	classid = task_cls_classid(current);
+	classid = task_cls_classid(task);
  	rcu_read_unlock();

Comment is now misleading (since task might not be current) and
rcu_read_lock()/rcu_read_unlock() protects nothing here, but avoid a
lockdep splat...

Hey task_cls_classid() has its own rcu protection since commit
3fb5a991916091a908d (cls_cgroup: Fix rcu lockdep warning)

So we can safely revert Paul commit (1144182a8757f2a1)
(We no longer need rcu_read_lock/unlock here)

Good point. Will update the series accordingly.

(BTW net-next is not opened yet, its content outdated, although I like
your patch series !)

I still have not figured all details on the patch submission procedure. Sorry about that. The time to send patches for net-next will be annonced by David, is this correct?