path: root/net
diff options
authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2009-04-01 23:18:20 +0000
committerDavid S. Miller <davem@davemloft.net>2009-04-02 16:31:45 -0700
commit9eb9362e569062e2f841b7a023e5fcde10ed63b4 (patch)
tree06dc2aa031ca9cd604ece8a9fd5c5bc8502b2257 /net
parent797108d134a91afca9fa59c572336b279bc66afb (diff)
tcp: miscounts due to tcp_fragment pcount reset
It seems that trivial reset of pcount to one was not sufficient in tcp_retransmit_skb. Multiple counters experience a positive miscount when skb's pcount gets lowered without the necessary adjustments (depending on skb's sacked bits which exactly), at worst a packets_out miscount can crash at RTO if the write queue is empty! Triggering this requires mss change, so bidir tcp or mtu probe or like. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Tested-by: Uwe Bugla <uwe.bugla@gmx.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
1 files changed, 6 insertions, 1 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f1db89bb3aa..53300fa2359 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1893,7 +1893,12 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
if (tcp_fragment(sk, skb, cur_mss, cur_mss))
return -ENOMEM; /* We'll try again later. */
} else {
- tcp_init_tso_segs(sk, skb, cur_mss);
+ int oldpcount = tcp_skb_pcount(skb);
+ if (unlikely(oldpcount > 1)) {
+ tcp_init_tso_segs(sk, skb, cur_mss);
+ tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb));
+ }
tcp_retrans_try_collapse(sk, skb, cur_mss);