cgroup: net_cls: Pass in task to sock_update_classid()

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.

Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Joe Perches <joe@perches.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <netdev@vger.kernel.org>
Cc: <cgroups@vger.kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index 9fedbbf..0a023b8 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1217,11 +1217,11 @@
 
 #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;
 
-	classid = task_cls_classid(current);
+	classid = task_cls_classid(task);
 	if (classid != sk->sk_classid)
 		sk->sk_classid = classid;
 }
@@ -1264,7 +1264,7 @@
 		sock_net_set(sk, get_net(net));
 		atomic_set(&sk->sk_wmem_alloc, 1);
 
-		sock_update_classid(sk);
+		sock_update_classid(sk, current);
 		sock_update_netprioidx(sk, current);
 	}