Redundant subflows are not supported in __mptcp_subflow_push_pending()
yet. This patch adds a placeholder in mptcp_sched_get_send() to pick the
first subflow for the redundant subflows case.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/protocol.c |  8 +++++---
 net/mptcp/sched.c    | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 8bf48387f9d8..bcaf91562e2b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1629,13 +1629,13 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
 		info.limit = dfrag->data_len;
 		len = dfrag->data_len - dfrag->already_sent;
 		while (len > 0) {
-			int ret = 0;
+			int ret = 0, err = 0;
 
 			/* the caller already invoked the packet scheduler,
 			 * check for a different subflow usage only after
 			 * spooling the first chunk of data
 			 */
-			xmit_ssk = first ? ssk : mptcp_subflow_get_send(mptcp_sk(sk));
+			xmit_ssk = first ? ssk : mptcp_sched_get_send(mptcp_sk(sk), &err);
 			if (!xmit_ssk)
 				goto out;
 			if (xmit_ssk != ssk) {
@@ -3109,11 +3109,13 @@ void __mptcp_data_acked(struct sock *sk)
 
 void __mptcp_check_push(struct sock *sk, struct sock *ssk)
 {
+	int err = 0;
+
 	if (!mptcp_send_head(sk))
 		return;
 
 	if (!sock_owned_by_user(sk)) {
-		struct sock *xmit_ssk = mptcp_subflow_get_send(mptcp_sk(sk));
+		struct sock *xmit_ssk = mptcp_sched_get_send(mptcp_sk(sk), &err);
 
 		if (xmit_ssk == ssk)
 			__mptcp_subflow_push_pending(sk, ssk);
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index a0585182a2b1..527ea07982c5 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -119,6 +119,7 @@ static int mptcp_sched_data_init(struct mptcp_sock *msk, bool reinject,
 
 struct sock *mptcp_sched_get_send(struct mptcp_sock *msk, int *err)
 {
+	struct mptcp_subflow_context *subflow;
 	struct mptcp_sched_data data;
 	struct sock *ssk = NULL;
 
@@ -147,5 +148,19 @@ struct sock *mptcp_sched_get_send(struct mptcp_sock *msk, int *err)
 	mptcp_sched_data_init(msk, false, &data);
 	msk->sched->get_subflow(msk, &data);
 
+	mptcp_for_each_subflow(msk, subflow) {
+		if (READ_ONCE(subflow->scheduled)) {
+			/*
+			 * TODO: Redundant subflows are not supported in
+			 * __mptcp_subflow_push_pending() yet. Here's a
+			 * placeholder to pick the first subflow for the
+			 * redundant subflows case.
+			 */
+			ssk = subflow->tcp_sock;
+			*err = 0;
+			break;
+		}
+	}
+
 	return ssk;
 }
-- 
2.34.1