netdev - Re: [RFC net-next] net: don't dump stack on queue timeout

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Message-ID: <CAGRyCJHiPcKnBkkCDxbannmJYLwZevvz8cnx88PcvnCeYULDaA@mail.gmail.com>
Date: Thu, 9 Nov 2023 08:40:00 +0100
From: Daniele Palmas <dnlplm@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com, 
	pabeni@...hat.com, syzbot+d55372214aff0faa1f1f@...kaller.appspotmail.com, 
	jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us
Subject: Re: [RFC net-next] net: don't dump stack on queue timeout

Hello Jakub,

Il giorno gio 9 nov 2023 alle ore 01:09 Jakub Kicinski
<kuba@...nel.org> ha scritto:
>
> The top syzbot report for networking (#14 for the entire kernel)
> is the queue timeout splat. We kept it around for a long time,
> because in real life it provides pretty strong signal that
> something is wrong with the driver or the device.
>
> Removing it is also likely to break monitoring for those who
> track it as a kernel warning.
>
> Nevertheless, WARN()ings are best suited for catching kernel
> programming bugs. If a Tx queue gets starved due to a pause
> storm, priority configuration, or other weirdness - that's
> obviously a problem, but not a problem we can fix at
> the kernel level.
>
> Bite the bullet and convert the WARN() to a print.
>

I can't comment on other scenarios, but at least for mobile broadband
I think this could be a useful change.

For example, I can see the splat with MBIM modems when radio link
failure happens, something for which the host can't really do
anything. So, the main result of using WARN is to scare the users who
are not aware of the reasons behind it and create unneeded support
requests...

Thanks,
Daniele