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

From: Ojaswin Mujoo <ojaswin98@gmail.com>
To: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
	nsaenz@kernel.org, gregkh@linuxfoundation.org, arnd@arndb.de,
	phil@raspberrypi.com, bcm-kernel-feedback-list@broadcom.com,
	linux-arm-kernel@lists.infradead.org,
	linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: staging: vc04_services: Need suggestions on trying to fix sparse warning in vchiq_arm.c
Date: Sat, 5 Jun 2021 12:53:31 +0530	[thread overview]
Message-ID: <20210605072249.GA5967@ojas> (raw)
In-Reply-To: <9ba341f7-17fc-980d-a7a0-2293c75dcf92@i2se.com>

On Fri, Jun 04, 2021 at 08:13:06AM +0200, Stefan Wahren wrote:
> 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
> 

Got it, Task 10 (cdev to its own file) seems like a pretty good task to
get started with. I'm planning to buy a Rpi 4 so I think I can run tests
on that. 

Thank you so much for the help, I'll get back incase I face any issues down 
the line.

Regards,
Ojaswin

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