netdev - [PATCH net-next 3/8] mptcp: schedule worker when subflow is closed

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Date:   Fri, 12 Feb 2021 15:59:56 -0800
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Florian Westphal <fw@...len.de>, davem@...emloft.net,
        kuba@...nel.org, mptcp@...ts.01.org, matthieu.baerts@...sares.net,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>
Subject: [PATCH net-next 3/8] mptcp: schedule worker when subflow is closed

From: Florian Westphal <fw@...len.de>

When remote side closes a subflow we should schedule the worker to
dispose of the subflow in a timely manner.

Otherwise, SF_CLOSED event won't be generated until the mptcp
socket itself is closing or local side is closing another subflow.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 net/mptcp/protocol.c |  4 ++++
 net/mptcp/subflow.c  | 25 +++++++++++++++++++++++--
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 3fd8aef979a3..267c5521692d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2170,6 +2170,10 @@ static void __mptcp_close_subflow(struct mptcp_sock *msk)
 		if (inet_sk_state_load(ssk) != TCP_CLOSE)
 			continue;
 
+		/* 'subflow_data_ready' will re-sched once rx queue is empty */
+		if (!skb_queue_empty_lockless(&ssk->sk_receive_queue))
+			continue;
+
 		mptcp_close_ssk((struct sock *)msk, ssk, subflow);
 	}
 }
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 280da418d60b..36b15726f851 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -953,6 +953,22 @@ static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
 		subflow->map_valid = 0;
 }
 
+/* sched mptcp worker to remove the subflow if no more data is pending */
+static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
+{
+	struct sock *sk = (struct sock *)msk;
+
+	if (likely(ssk->sk_state != TCP_CLOSE))
+		return;
+
+	if (skb_queue_empty(&ssk->sk_receive_queue) &&
+	    !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) {
+		sock_hold(sk);
+		if (!schedule_work(&msk->work))
+			sock_put(sk);
+	}
+}
+
 static bool subflow_check_data_avail(struct sock *ssk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
@@ -991,11 +1007,11 @@ static bool subflow_check_data_avail(struct sock *ssk)
 		}
 
 		if (status != MAPPING_OK)
-			return false;
+			goto no_data;
 
 		skb = skb_peek(&ssk->sk_receive_queue);
 		if (WARN_ON_ONCE(!skb))
-			return false;
+			goto no_data;
 
 		/* if msk lacks the remote key, this subflow must provide an
 		 * MP_CAPABLE-based mapping
@@ -1029,6 +1045,9 @@ static bool subflow_check_data_avail(struct sock *ssk)
 	}
 	return true;
 
+no_data:
+	subflow_sched_work_if_closed(msk, ssk);
+	return false;
 fatal:
 	/* fatal protocol error, close the socket */
 	/* This barrier is coupled with smp_rmb() in tcp_poll() */
@@ -1413,6 +1432,8 @@ static void subflow_state_change(struct sock *sk)
 	if (mptcp_subflow_data_available(sk))
 		mptcp_data_ready(parent, sk);
 
+	subflow_sched_work_if_closed(mptcp_sk(parent), sk);
+
 	if (__mptcp_check_fallback(mptcp_sk(parent)) &&
 	    !subflow->rx_eof && subflow_is_done(sk)) {
 		subflow->rx_eof = 1;
-- 
2.30.1