linux-kernel - Re: staging: vc04_services: Need suggestions on trying to fix sparse warning in vchiq_arm.c

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Message-ID: <9ba341f7-17fc-980d-a7a0-2293c75dcf92@i2se.com>
Date:   Fri, 4 Jun 2021 08:13:06 +0200
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Ojaswin Mujoo <ojaswin98@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     nsaenz@...nel.org, gregkh@...uxfoundation.org, arnd@...db.de,
        phil@...pberrypi.com, bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: staging: vc04_services: Need suggestions on trying to fix sparse
 warning in vchiq_arm.c

Hi Ojaswin,

Am 02.06.21 um 16:50 schrieb Ojaswin Mujoo:
> On Tue, Jun 01, 2021 at 11:23:07PM +0300, Dan Carpenter wrote:
>> The problem is not the Sparse warning, the problem is that this code is
>> a mess.  It used to very clearly buggy and I reported the bug.  I think
>> Arnd found the bug again independently and fixed it.
>>
>> A couple weeks ago Al Viro looked at this code.  Here is his write up:
>>
>> https://www.spinics.net/lists/kernel/msg3952745.html
>>
>> It shouldn't take Al Viro dozens of pages of detailed analysis to try
>> figure out if the code is safe or not.  Your idea silences the warning
>> but would make the code even more subtle and complicated.
>>
>> The right thing to do is to re-write the code to be simpler.
>>
>> regards,
>> dan carpenter
>>
> Thank you for the prompt reply and the link, it was very insightful. You
> are right, I was definitely going about this the wrong way and missing
> the larger picture. I'll spend some time trying to understand this
> codebase as I think that'd be a good start to understand how stuff works in
> the kernel (even though some of the things in this driver are anti patterns)
> and hopefully get some ideas on ways to clean this up.
>
> Anyways, thanks again for the help, cheers!

thanks for your interest in cleaning this up. Yes, it's not clear which
points on the TODO list are the lower hanging fruits. In case you don't
want to fix checkpatch issues, maybe you can look at points 8, 9, 10, 12
and 13. Most of them require testing with a Raspberry Pi, but feel free
to ask if you have problems with it.

Regards
Stefan

>
> Ojaswin
>
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> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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