This patch adds the redundant subflows support for __mptcp_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 | 99 ++++++++++++++++++++++++++------------------
 1 file changed, 58 insertions(+), 41 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 15472d0af508..0be43107170c 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1516,63 +1516,80 @@ void mptcp_check_and_set_pending(struct sock *sk)
 
 void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 {
-	struct sock *prev_ssk = NULL, *ssk = NULL;
 	struct mptcp_sock *msk = mptcp_sk(sk);
-	struct mptcp_sendmsg_info info = {
-				.flags = flags,
-	};
+	struct mptcp_subflow_context *subflow;
 	struct mptcp_data_frag *dfrag;
-	int len, copied = 0;
+	int len, max = 0, err = 0;
 
-	while ((dfrag = mptcp_send_head(sk))) {
-		info.sent = dfrag->already_sent;
-		info.limit = dfrag->data_len;
-		len = dfrag->data_len - dfrag->already_sent;
-		while (len > 0) {
-			int ret = 0;
+	mptcp_sched_get_send(msk, &err);
+	if (err)
+		goto out;
 
-			prev_ssk = ssk;
-			ssk = mptcp_subflow_get_send(msk);
+	dfrag = mptcp_send_head(sk);
+	if (!dfrag)
+		goto out;
 
-			/* First check. If the ssk has changed since
-			 * the last round, release prev_ssk
-			 */
-			if (ssk != prev_ssk && prev_ssk)
-				mptcp_push_release(prev_ssk, &info);
-			if (!ssk)
-				goto out;
+	mptcp_for_each_subflow(msk, subflow) {
+		if (READ_ONCE(subflow->scheduled)) {
+			struct sock *prev_ssk = NULL, *ssk = NULL;
+			struct mptcp_sendmsg_info info = {
+				.flags = flags,
+			};
+			int copied = 0;
 
-			/* Need to lock the new subflow only if different
-			 * from the previous one, otherwise we are still
-			 * helding the relevant lock
-			 */
-			if (ssk != prev_ssk)
-				lock_sock(ssk);
+			info.sent = dfrag->already_sent;
+			info.limit = dfrag->data_len;
+			len = dfrag->data_len - dfrag->already_sent;
+			while (len > 0) {
+				int ret = 0;
 
-			ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
-			if (ret <= 0) {
-				mptcp_push_release(ssk, &info);
-				goto out;
-			}
+				prev_ssk = ssk;
+				ssk = mptcp_subflow_tcp_sock(subflow);
 
-			info.sent += ret;
-			copied += ret;
-			len -= ret;
+				/* First check. If the ssk has changed since
+				 * the last round, release prev_ssk
+				 */
+				if (ssk != prev_ssk && prev_ssk)
+					mptcp_push_release(prev_ssk, &info);
+				if (!ssk)
+					goto out;
+
+				/* Need to lock the new subflow only if different
+				 * from the previous one, otherwise we are still
+				 * helding the relevant lock
+				 */
+				if (ssk != prev_ssk)
+					lock_sock(ssk);
+
+				ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
+				if (ret <= 0) {
+					mptcp_push_release(ssk, &info);
+					goto out;
+				}
+
+				info.sent += ret;
+				copied += ret;
+				len -= ret;
+			}
+			max = max(copied, max);
 
-			mptcp_update_post_push(msk, dfrag, ret);
+			/* at this point we held the socket lock for the last subflow we used */
+			if (ssk) {
+				mptcp_push_release(ssk, &info);
+				msk->last_snd = ssk;
+				mptcp_subflow_set_scheduled(subflow, false);
+			}
 		}
-		WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
 	}
-
-	/* at this point we held the socket lock for the last subflow we used */
-	if (ssk)
-		mptcp_push_release(ssk, &info);
+	if (max)
+		mptcp_update_post_push(msk, dfrag, max);
+	WRITE_ONCE(msk->first_pending, mptcp_send_next(sk));
 
 out:
 	/* ensure the rtx timer is running */
 	if (!mptcp_timer_pending(sk))
 		mptcp_reset_timer(sk);
-	if (copied)
+	if (max)
 		__mptcp_check_send_data_fin(sk);
 }
 
-- 
2.35.3