linux-kernel - Re: [PATCH net-next v4 00/10] net: netconsole refactoring and warning fix

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Message-ID: <20241004-shaggy-spectacular-moose-1b3bd6@leitao>
Date: Fri, 4 Oct 2024 01:50:13 -0700
From: Breno Leitao <leitao@...ian.org>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
	thepacketgeek@...il.com, horms@...nel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, davej@...emonkey.org.uk,
	max@...sevol.com
Subject: Re: [PATCH net-next v4 00/10] net: netconsole refactoring and
 warning fix

On Thu, Oct 03, 2024 at 05:29:50PM -0700, Jakub Kicinski wrote:
> On Mon, 30 Sep 2024 06:11:59 -0700 Breno Leitao wrote:
> > To address these issues, the following steps were taken:
> > 
> >  * Breaking down write_ext_msg() into smaller functions with clear scopes
> >  * Improving readability and reasoning about the code
> >  * Simplifying and clarifying naming conventions
> > 
> > Warning Fix
> > -----------
> > 
> > The warning occurred when there was insufficient buffer space to append
> > userdata. While this scenario is acceptable (as userdata can be sent in a
> > separate packet later), the kernel was incorrectly raising a warning.  A
> > one-line fix has been implemented to resolve this issue.
> > 
> > A self-test was developed to write messages of every possible length
> > This test will be submitted in a separate patchset
> 
> Makes sense in general, but why isn't the fix sent to net first, 
> and then once the trees converge (follow Thursday) we can apply 
> the refactoring and improvements on top?
> 
> The false positive warning went into 6.9 if I'm checking correctly.

Correct. I probably should have separated the fix from the refactor.

For context, I was pursuing the warning, and the code was hard to read,
so, I was refactoring the code while narrowing down the warning.

But you are correct, the warning is in 6.9+ kernels. But, keep in mind
that the warning is very hard to trigger, basically the length of userdata
and the message needs to be certain size to trigger it.