[PATCH v2 9/9] tcp: Skip redundant ACK on partial sendmsg() failure

[Stefano Brivio <sbrivio@redhat.com>]

...we'll send a duplicate ACK right away in this case, and this
redundant, earlier check is not just useless, but it might actually
be harmful as we'll now send a triple ACK which might cause two
retransmissions.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/tcp.c b/tcp.c
index fa22e9b..9252495 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2024,13 +2024,10 @@ eintr:
 		return -1;
 	}
 
-	if (n < (int)(seq_from_tap - conn->seq_from_tap)) {
+	if (n < (int)(seq_from_tap - conn->seq_from_tap))
 		partial_send = 1;
-		conn->seq_from_tap += n;
-		tcp_send_flag(c, conn, ACK_IF_NEEDED);
-	} else {
-		conn->seq_from_tap += n;
-	}
+
+	conn->seq_from_tap += n;
 
 out:
 	if (keep != -1 || partial_send) {
-- 
2.43.0