mptcp: introduce mptcp_schedule_work

remove some of code duplications an allow preventing
rescheduling on close.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/mptcp/pm.c

@@ -89,8 +89,7 @@ static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
 		return false;
 
 	msk->pm.status |= BIT(new_status);
-	if (schedule_work(&msk->work))
-		sock_hold((struct sock *)msk);
+	mptcp_schedule_work((struct sock *)msk);
 	return true;
 }
 

net/mptcp/protocol.c

@@ -620,9 +620,8 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
 		 * this is not a good place to change state. Let the workqueue
 		 * do it.
 		 */
-		if (mptcp_pending_data_fin(sk, NULL) &&
-		    schedule_work(&msk->work))
-			sock_hold(sk);
+		if (mptcp_pending_data_fin(sk, NULL))
+			mptcp_schedule_work(sk);
 	}
 
 	spin_unlock_bh(&sk->sk_lock.slock);
@@ -699,23 +698,32 @@ static void mptcp_reset_timer(struct sock *sk)
 	sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
 }
 
+bool mptcp_schedule_work(struct sock *sk)
+{
+	if (inet_sk_state_load(sk) != TCP_CLOSE &&
+	    schedule_work(&mptcp_sk(sk)->work)) {
+		/* each subflow already holds a reference to the sk, and the
+		 * workqueue is invoked by a subflow, so sk can't go away here.
+		 */
+		sock_hold(sk);
+		return true;
+	}
+	return false;
+}
+
 void mptcp_data_acked(struct sock *sk)
 {
 	mptcp_reset_timer(sk);
 
 	if ((!test_bit(MPTCP_SEND_SPACE, &mptcp_sk(sk)->flags) ||
-	     (inet_sk_state_load(sk) != TCP_ESTABLISHED)) &&
-	    schedule_work(&mptcp_sk(sk)->work))
-		sock_hold(sk);
+	     (inet_sk_state_load(sk) != TCP_ESTABLISHED)))
+		mptcp_schedule_work(sk);
 }
 
 void mptcp_subflow_eof(struct sock *sk)
 {
-	struct mptcp_sock *msk = mptcp_sk(sk);
-
-	if (!test_and_set_bit(MPTCP_WORK_EOF, &msk->flags) &&
-	    schedule_work(&msk->work))
-		sock_hold(sk);
+	if (!test_and_set_bit(MPTCP_WORK_EOF, &mptcp_sk(sk)->flags))
+		mptcp_schedule_work(sk);
 }
 
 static void mptcp_check_for_eof(struct mptcp_sock *msk)
@@ -1620,8 +1628,7 @@ static void mptcp_retransmit_handler(struct sock *sk)
 		mptcp_stop_timer(sk);
 	} else {
 		set_bit(MPTCP_WORK_RTX, &msk->flags);
-		if (schedule_work(&msk->work))
-			sock_hold(sk);
+		mptcp_schedule_work(sk);
 	}
 }
 
@@ -2334,7 +2341,8 @@ static void mptcp_release_cb(struct sock *sk)
 		struct sock *ssk;
 
 		ssk = mptcp_subflow_recv_lookup(msk);
-		if (!ssk || !schedule_work(&msk->work))
+		if (!ssk || sk->sk_state == TCP_CLOSE ||
+		    !schedule_work(&msk->work))
 			__sock_put(sk);
 	}
 

net/mptcp/protocol.h

@@ -408,6 +408,7 @@ static inline bool mptcp_is_fully_established(struct sock *sk)
 void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk);
 void mptcp_data_ready(struct sock *sk, struct sock *ssk);
 bool mptcp_finish_join(struct sock *sk);
+bool mptcp_schedule_work(struct sock *sk);
 void mptcp_data_acked(struct sock *sk);
 void mptcp_subflow_eof(struct sock *sk);
 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit);