On Wed, 2012-10-17 at 15:04 +0200, Daniel Wagner wrote:
> From: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>
>
> 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.
>
...
>
> -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)
(BTW net-next is not opened yet, its content outdated, although I like
your patch series !)
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