From 692767dfebce10bc997073eb707a934348cdfe08 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 10 Oct 2007 03:25:53 -0700 Subject: [PATCH] Fix TCP's ->fastpath_cnt_hit handling. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit changeset 48611c47d09023d9356e78550d1cadb8d61da9c8 in mainline. 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 Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 5bfda70a6a56..e33fb3d0b8cc 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2403,6 +2403,9 @@ 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); -- 2.39.5