This patch adds the multiple subflows support for
__mptcp_subflow_push_pending(). Use mptcp_sched_get_send() wrapper
instead of mptcp_subflow_get_send() in it.

Check the subflow scheduled flags to test which subflow or subflows are
picked by the scheduler, use them to send data.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/protocol.c | 50 +++++++++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 14 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 56c76cae93ba..0dfe78c0856f 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1617,32 +1617,54 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk, bool first)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
+	struct mptcp_subflow_context *subflow;
 	struct mptcp_sendmsg_info info = {
 		.data_lock_held = true,
 	};
-	struct sock *xmit_ssk;
 	int ret = 0;
 
 	info.flags = 0;
+again:
 	while (mptcp_send_head(sk)) {
 		/* check for a different subflow usage only after
 		 * spooling the first chunk of data
 		 */
-		xmit_ssk = first ? ssk : mptcp_subflow_get_send(msk);
-		if (!xmit_ssk)
-			goto out;
-		if (xmit_ssk != ssk) {
-			mptcp_subflow_delegate(mptcp_subflow_ctx(xmit_ssk),
-					       MPTCP_DELEGATE_SEND);
-			goto out;
+		if (first) {
+			ret = __subflow_push_pending(sk, ssk, &info);
+			first = false;
+			if (ret <= 0) {
+				if (ret == -EAGAIN)
+					goto again;
+				break;
+			}
+			msk->sched->last_snd = ssk;
+			continue;
 		}
 
-		ret = __subflow_push_pending(sk, ssk, &info);
-		first = false;
-		if (ret <= 0) {
-			if (ret == -EAGAIN)
-				continue;
-			break;
+		if (mptcp_sched_get_send(msk))
+			goto out;
+
+		mptcp_for_each_subflow(msk, subflow) {
+			if (READ_ONCE(subflow->scheduled)) {
+				struct sock *xmit_ssk = mptcp_subflow_tcp_sock(subflow);
+
+				if (xmit_ssk != ssk) {
+					mptcp_subflow_delegate(subflow,
+							       MPTCP_DELEGATE_SEND);
+					msk->sched->last_snd = ssk;
+					mptcp_subflow_set_scheduled(subflow, false);
+					goto out;
+				}
+
+				ret = __subflow_push_pending(sk, ssk, &info);
+				if (ret <= 0) {
+					if (ret == -EAGAIN)
+						goto again;
+					goto out;
+				}
+				msk->sched->last_snd = ssk;
+				mptcp_subflow_set_scheduled(subflow, false);
+			}
 		}
 	}
 
-- 
2.35.3