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tcp: Split handling of DUP_ACK from ACK

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The DUP_ACK flag to tcp_send_flag() has two effects: first it forces the
setting of the ACK flag in the packet, even if we otherwise wouldn't.
Secondly, it causes a duplicate of the flags packet to be sent immediately
after the first.

Setting the ACK flag to tcp_send_flag() also has the first effect, so
instead of having DUP_ACK also do that, pass both flags when we need both
operations.  This slightly simplifies the logic of tcp_send_flag() in a way
that makes some future changes easier.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-03-26 16:42:21 +11:00 committed by Stefano Brivio
parent 71dd405460
commit 99355e25b9
1 changed files with 2 additions and 2 deletions
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4
tcp.c
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@ -1677,7 +1677,7 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
th->ack = !!(flags & ACK); th->ack = !!(flags & ACK);
} else { } else {
th->ack = !!(flags & (ACK | DUP_ACK)) || th->ack = !!(flags & ACK)) ||
conn->seq_ack_to_tap != prev_ack_to_tap || conn->seq_ack_to_tap != prev_ack_to_tap ||
!prev_wnd_to_tap; !prev_wnd_to_tap;
} }
@ -2503,7 +2503,7 @@ out:
*/ */
if (conn->seq_dup_ack_approx != (conn->seq_from_tap & 0xff)) { if (conn->seq_dup_ack_approx != (conn->seq_from_tap & 0xff)) {
conn->seq_dup_ack_approx = conn->seq_from_tap & 0xff; conn->seq_dup_ack_approx = conn->seq_from_tap & 0xff;
tcp_send_flag(c, conn, DUP_ACK); tcp_send_flag(c, conn, ACK | DUP_ACK);
} }
return p->count - idx; return p->count - idx;
} }