From: Ilpo Järvinen Date: Mon, 8 Oct 2007 06:43:10 +0000 (-0700) Subject: [TCP]: Fix fastpath_cnt_hint when GSO skb is partially ACKed X-Git-Tag: v2.6.23~6^2~3 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=48611c47d09023d9356e78550d1cadb8d61da9c8;p=linux-2.6 [TCP]: Fix fastpath_cnt_hint when GSO skb is partially ACKed When only GSO skb was partially ACKed, no hints are reset, therefore fastpath_cnt_hint must be tweaked too or else it can corrupt fackets_out. The corruption to occur, one must have non-trivial ACK/SACK sequence, so this bug is not very often that harmful. There's a fackets_out state reset in TCP because fackets_out is known to be inaccurate and that fixes the issue eventually anyway. In case there was also at least one skb that got fully ACKed, the fastpath_skb_hint is set to NULL which causes a recount for fastpath_cnt_hint (the old value won't be accessed anymore), thus it can safely be decremented without additional checking. Reported by Cedric Le Goater Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index bbad2cdb74..f893e90061 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2420,6 +2420,9 @@ static int tcp_tso_acked(struct sock *sk, struct sk_buff *skb, __u32 dval = min(tp->fackets_out, packets_acked); tp->fackets_out -= dval; } + /* hint's skb might be NULL but we don't need to care */ + tp->fastpath_cnt_hint -= min_t(u32, packets_acked, + tp->fastpath_cnt_hint); tp->packets_out -= packets_acked; BUG_ON(tcp_skb_pcount(skb) == 0);