netdev - [PATCH net 6/6] mptcp: add a missing retransmission timer scheduling

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Date:   Thu, 11 Feb 2021 15:30:42 -0800
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Paolo Abeni <pabeni@...hat.com>, 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 6/6] mptcp: add a missing retransmission timer scheduling

From: Paolo Abeni <pabeni@...hat.com>

Currently we do not schedule the MPTCP retransmission
timer after pushing the data when such action happens
in the subflow context.

This may cause hang-up on active-backup scenarios, or
even when only single subflow msks are involved, if we lost
some peer's ack.

Fixes: 6e628cd3a8f7 ("mptcp: use mptcp release_cb for delayed tasks")
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 net/mptcp/options.c  | 3 +--
 net/mptcp/protocol.c | 3 +++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 82a37cc26776..8fec3dabe109 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -880,8 +880,7 @@ static void ack_update_msk(struct mptcp_sock *msk,
 		msk->wnd_end = new_wnd_end;
 
 	/* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
-	if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)) &&
-	    sk_stream_memory_free(ssk))
+	if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
 		__mptcp_check_push(sk, ssk);
 
 	if (after64(new_snd_una, old_snd_una)) {
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 0dbf5cbd7e56..06da6ad31c87 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1582,6 +1582,9 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
 		mptcp_set_timeout(sk, ssk);
 		tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
 			 info.size_goal);
+		if (!mptcp_timer_pending(sk))
+			mptcp_reset_timer(sk);
+
 		if (msk->snd_data_fin_enable &&
 		    msk->snd_nxt + 1 == msk->write_seq)
 			mptcp_schedule_work(sk);
-- 
2.30.1