netdev - Re: [PATCH net v2 1/1] net: tcp: Permit user set TCP

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Date:   Tue, 21 Mar 2017 09:27:36 +0800
From:   Feng Gao <gfree.wind@...il.com>
To:     Neal Cardwell <ncardwell@...gle.com>
Cc:     David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net v2 1/1] net: tcp: Permit user set TCP_MAXSEG to
 default value

On Tue, Mar 21, 2017 at 9:23 AM, Neal Cardwell <ncardwell@...gle.com> wrote:
> On Mon, Mar 20, 2017 at 8:45 PM, <fgao@...ai8.com> wrote:
>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>> index 1e319a5..4f7f163 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -2470,7 +2470,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
>>                 /* Values greater than interface MTU won't take effect. However
>>                  * at the point when this call is done we typically don't yet
>>                  * know which interface is going to be used */
>> -               if (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW) {
>> +               if (!val && (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW)) {
>>                         err = -EINVAL;
>>                         break;
>
> I believe the sense of the val check is flipped in the proposed patch.
>
> I believe Eric suggested:
>
>   if (val && (val < TCP_MIN_MSS || val > MAX_TCP_WINDOW)) {
>
> Has this been tested?
>
> neal

Sorry, I missed the test this time because of the minor fix.
As a result, wrote the wrong logic.

Regards
Feng