[PATCH v5 mptcp-next 17/21] mptcp: tune re-injections for csum enabled mode.

[Paolo Abeni <pabeni@redhat.com>]

If the MPTCP-level checksum is enabled, on re-injections we
must spool a complete DSS, or the receive side will not be
able to compute the csum and process any data.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/protocol.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 2a9327f5c14c..32a39774075b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2333,8 +2333,8 @@ static void __mptcp_retrans(struct sock *sk)
 
 	/* limit retransmission to the bytes already sent on some subflows */
 	info.sent = 0;
-	info.limit = dfrag->already_sent;
-	while (info.sent < dfrag->already_sent) {
+	info.limit = READ_ONCE(msk->csum_enabled) ? dfrag->data_len : dfrag->already_sent;
+	while (info.sent < info.limit) {
 		if (!mptcp_alloc_tx_skb(sk, ssk))
 			break;
 
@@ -2346,9 +2346,11 @@ static void __mptcp_retrans(struct sock *sk)
 		copied += ret;
 		info.sent += ret;
 	}
-	if (copied)
+	if (copied) {
+		dfrag->already_sent = max(dfrag->already_sent, info.sent);
 		tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
 			 info.size_goal);
+	}
 
 	mptcp_set_timeout(sk, ssk);
 	release_sock(ssk);
-- 
2.26.2