* [RFC] tcp: remove BUG_ON in tcp_shifted_skb
@ 2020-01-17 2:03 Li,Rongqing
2020-01-17 2:59 ` Eric Dumazet
0 siblings, 1 reply; 2+ messages in thread
From: Li,Rongqing @ 2020-01-17 2:03 UTC (permalink / raw)
To: edumazet@google.com; +Cc: netdev@vger.kernel.org
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@baidu.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
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [RFC] tcp: remove BUG_ON in tcp_shifted_skb
2020-01-17 2:03 [RFC] tcp: remove BUG_ON in tcp_shifted_skb Li,Rongqing
@ 2020-01-17 2:59 ` Eric Dumazet
0 siblings, 0 replies; 2+ messages in thread
From: Eric Dumazet @ 2020-01-17 2:59 UTC (permalink / raw)
To: Li,Rongqing; +Cc: netdev@vger.kernel.org
On Thu, Jan 16, 2020 at 6:03 PM Li,Rongqing <lirongqing@baidu.com> wrote:
>
> 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 ?
I doubt it. Please provide a packetdrill test if you think otherwise.
>
> - Li RongQing <lirongqing@baidu.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));
I understand people can be worried about BUG_ON(), but they serve to
spot bugs when a patch breaks something horribly.
^ permalink raw reply [flat|nested] 2+ messages in thread
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