netdev - [RFC] tcp: remove BUG_ON in tcp_shifted

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Date:   Fri, 17 Jan 2020 02:03:45 +0000
From:   "Li,Rongqing" <lirongqing@...du.com>
To:     "edumazet@...gle.com" <edumazet@...gle.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [RFC] tcp: remove BUG_ON in tcp_shifted_skb

I think this BUG_ON in tcp_shifted_skb maybe be triggered if a GSO skb is 
sacked, but sack is faked, and not ack the whole mss length, only ack less
than mss length

Is it possible ?

- Li RongQing <lirongqing@...du.com>

---
 net/ipv4/tcp_input.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1d1e3493965f..141bc85092b5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1327,7 +1327,8 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
        TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
 
        if (skb->len > 0) {
-               BUG_ON(!tcp_skb_pcount(skb));
                NET_INC_STATS(sock_net(sk), LINUX_MIB_SACKSHIFTED);
                return false;
        }
-- 
2.16.2