netdev - Re: [Patch net] atm: remove an unnecessary loop

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Message-ID: <CAM_iQpXd8qTTRT_+CkHnpMNC=CSS9vfB6zKtSjmLV_yya5BL8Q@mail.gmail.com>
Date:   Fri, 13 Jan 2017 10:20:33 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     Francois Romieu <romieu@...zoreil.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Michal Hocko <mhocko@...nel.org>,
        Chas Williams <3chas3@...il.com>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: Re: [Patch net] atm: remove an unnecessary loop

On Fri, Jan 13, 2017 at 9:10 AM, David Miller <davem@...emloft.net> wrote:
> From: Francois Romieu <romieu@...zoreil.com>
> Date: Fri, 13 Jan 2017 01:07:00 +0100
>
>> Were alloc_skb moved one level up in the call stack, there would be
>> no need to use the new wait api in the subsequent page, thus easing
>> pre 3.19 longterm kernel maintenance (at least those on korg page).
>>
>> But it tastes a tad bit too masochistic.
>
> Lack of error handling of allocation failure is always a huge red
> flag.  We even long ago tried to do something like this for TCP FIN
> handling.
>
> It's dumb, it doesn't work.
>
> Therefore I agree that the correct fix is to move the SKB allocation
> up one level to vcc_sendmsg() and make it handle errors properly.

If you can justify API is not broken by doing that, I am more than happy
to do it, as I already stated in the latter patch:

"Of course, the logic itself is suspicious, other sendmsg()
could handle skb allocation failure very well, not sure
why ATM has to wait for a successful one here. But probably
it is too late to change since the errno and behavior is
visible to user-space. So just leave the logic as it is."

For some reason, no one reads that patch. :-/