mptcp: hold msk lock before removing id 0 address

In mptcp_pm_nl_remove_doit(), move 'lock_sock(sk)' before invoking the
function mptcp_userspace_pm_remove_id_zero_address(). Then no need to
hold and release this lock in this function. And 'sk' and 'err' variables
and 'remove_err' label in it can be dropped.

Signed-off-by: Geliang Tang <[email protected]>

Author: Geliang Tang

net/mptcp/pm_userspace.c

@@ -256,31 +256,24 @@ static int mptcp_userspace_pm_remove_id_zero_address(struct mptcp_sock *msk)
 {
 	struct mptcp_rm_list list = { .nr = 0 };
 	struct mptcp_subflow_context *subflow;
-	struct sock *sk = (struct sock *)msk;
 	bool has_id_0 = false;
-	int err = -EINVAL;
 
-	lock_sock(sk);
 	mptcp_for_each_subflow(msk, subflow) {
 		if (READ_ONCE(subflow->local_id) == 0) {
 			has_id_0 = true;
 			break;
 		}
 	}
 	if (!has_id_0)
-		goto remove_err;
+		return -EINVAL;
 
 	list.ids[list.nr++] = 0;
 
 	spin_lock_bh(&msk->pm.lock);
 	mptcp_pm_remove_addr(msk, &list);
 	spin_unlock_bh(&msk->pm.lock);
 
-	err = 0;
-
-remove_err:
-	release_sock(sk);
-	return err;
+	return 0;
 }
 
 void mptcp_pm_remove_addr_entry(struct mptcp_sock *msk,
@@ -324,13 +317,14 @@ int mptcp_pm_nl_remove_doit(struct sk_buff *skb, struct genl_info *info)
 
 	sk = (struct sock *)msk;
 
+	lock_sock(sk);
+
 	if (id_val == 0) {
 		err = mptcp_userspace_pm_remove_id_zero_address(msk);
+		release_sock(sk);
 		goto out;
 	}
 
-	lock_sock(sk);
-
 	spin_lock_bh(&msk->pm.lock);
 	match = mptcp_userspace_pm_lookup_addr_by_id(msk, id_val);
 	if (!match) {