On Wed, 28 Mar 2007, Patrick McHardy wrote:

I got this warning with the current net-2.6.22 tree:

KERNEL: assertion ((int)tp->sacked_out >= 0) failed at
net/ipv4/tcp_input.c (2626)
Leak s=4294967292 3

Can't say what exactly triggered it.

It seems I'm being guilty to this one, Dave please apply to net-2.6.22 
(besides this I think the tcp_sync_left_out should be changed but I'll 
prepare a patch for that later). Btw, how should this kind of email with 
some non-patch description+patch be formatted?).

[PATCH] [TCP]: Timedout loop must skip SACKed skbs too while marking

Marking skb with both S and L is invalid, and that could easily
happen in the timedout loop. Later on the tcp_sync_left_out
reduces sacked_out if lost_out + sacked_out > packets_out and
then eventually sacked_out underflows triggering a debug trap in
tcp_clean_rtx_queue.

Signed-off-by: Ilpo Järvinen <redacted>
---
 net/ipv4/tcp_input.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d116887..7a59ffe 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c

@@ -1777,7 +1777,8 @@ static void tcp_timedout_mark_forward(st
 		if (skb == tcp_send_head(sk) || !tcp_skb_timedout(sk, skb))
 			break;
 		/* Could be lost already from a previous timedout check */
-		if (!(TCP_SKB_CB(skb)->sacked & TCPCB_LOST)) {
+		if (!(TCP_SKB_CB(skb)->sacked &
+		     (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
 			TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
 			tp->lost_out += tcp_skb_pcount(skb);
 			tcp_verify_retransmit_hint(tp, skb);

-- 
1.4.2