netdev - Re: [PATCH v2 net-next] inet: Remove an unnecessary argument of syn_ack

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Message-ID: <cb795577-4759-3ab6-43c9-7a4f9c8d832f@gmail.com>
Date:   Sun, 5 Jul 2020 10:08:08 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
        "David S . Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Kuniyuki Iwashima <kuni1840@...il.com>,
        Benjamin Herrenschmidt <benh@...zon.com>,
        osa-contribution-log@...zon.com, Julian Anastasov <ja@....bg>
Subject: Re: [PATCH v2 net-next] inet: Remove an unnecessary argument of
 syn_ack_recalc().



On 7/4/20 8:28 AM, Kuniyuki Iwashima wrote:
> Commit 0c3d79bce48034018e840468ac5a642894a521a3 ("tcp: reduce SYN-ACK
> retrans for TCP_DEFER_ACCEPT") introduces syn_ack_recalc() which decides
> if a minisock is held and a SYN+ACK is retransmitted or not.
> 
> If rskq_defer_accept is not zero in syn_ack_recalc(), max_retries always
> has the same value because max_retries is overwritten by rskq_defer_accept
> in reqsk_timer_handler().
> 
> This commit adds two changes:
> - remove max_retries from the arguments of syn_ack_recalc() and use
>    rskq_defer_accept instead.
> - rename thresh to max_retries for readability.
> 

Honestly this looks unnecessary code churn to me.

This will make future backports more error prone.

Real question is : why do you want this change in the first place ?