Re: [REGRESSION] Warning in tcp_fastretrans_alert() of net/ipv4/tcp_input.c

From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: Yuchung Cheng <ycheng@google.com>
Cc: Eric Dumazet <edumazet@google.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Roman Gushchin <guro@fb.com>, netdev <netdev@vger.kernel.org>,
	Neal Cardwell <ncardwell@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Lawrence Brakmo <brakmo@fb.com>
Subject: Re: [REGRESSION] Warning in tcp_fastretrans_alert() of net/ipv4/tcp_input.c
Date: Fri, 10 Nov 2017 14:15:01 +0100	[thread overview]
Message-ID: <bb3221cc4b051b0f63bcec2e7489bb8e@natalenko.name> (raw)
In-Reply-To: <CAK6E8=cqO3owoDbUoZ-gTsYYdthNFNDa7KEHQX-4FLZZqfx3Mg@mail.gmail.com>

Hi.

I'm running the machine with this patch applied for 7 hours now, and the 
warning hasn't appeared yet. Typically, it should be there within the 
first hour.

I'll keep an eye on it for a longer time, but as of now it looks good.

Some explanation on this please?

Thanks!

06.11.2017 23:27, Yuchung Cheng wrote:
...snip...
> hi guys can you try if the warning goes away w/ this quick fix?
> 
> 
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 0ada8bfc2ebd..072aab2a8226 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -2626,7 +2626,7 @@ void tcp_simple_retransmit(struct sock *sk)
> 
>         tcp_clear_retrans_hints_partial(tp);
> 
> -       if (prior_lost == tp->lost_out)
> +       if (!tp->lost_out)
>                 return;
> 
>         if (tcp_is_reno(tp))
...snip...