[PATCH v2 8/9] tcp: Send a duplicate ACK also on complete sendmsg() failure

[Stefano Brivio <sbrivio@redhat.com>]

...in order to trigger a fast retransmit as soon as possible. There's
no benefit in forcing the sender to wait for a longer time than that.

We already do this on partial failures (short socket writes), but for
historical reason not on complete failures. Make these two cases
consistent between each other.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tcp.c b/tcp.c
index 60a9687..fa22e9b 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2017,7 +2017,7 @@ eintr:
 			goto eintr;
 
 		if (errno == EAGAIN || errno == EWOULDBLOCK) {
-			tcp_send_flag(c, conn, ACK_IF_NEEDED);
+			tcp_send_flag(c, conn, ACK | DUP_ACK);
 			return p->count - idx;
 
 		}
-- 
2.43.0