Re: [PATCH 6/8] spi: spi-s3c64xx: Check return values

From: Krzysztof Kozlowski <krzk@kernel.org>
To: Lukasz Stelmach <l.stelmach@samsung.com>
Cc: Kukjin Kim <kgene@kernel.org>, Andi Shyti <andi@etezian.org>,
	Mark Brown <broonie@kernel.org>,
	linux-spi@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, m.szyprowski@samsung.com,
	b.zolnierkie@samsung.com
Subject: Re: [PATCH 6/8] spi: spi-s3c64xx: Check return values
Date: Wed, 19 Aug 2020 18:13:23 +0200	[thread overview]
Message-ID: <20200819161323.GA8067@kozik-lap> (raw)
In-Reply-To: <dleftjwo1uzlqg.fsf%l.stelmach@samsung.com>

On Wed, Aug 19, 2020 at 05:41:43PM +0200, Lukasz Stelmach wrote:
> It was <2020-08-19 śro 14:48>, when Krzysztof Kozlowski wrote:
> > On Wed, Aug 19, 2020 at 02:32:06PM +0200, Łukasz Stelmach wrote:
> >> Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
> >> ---
> >>  drivers/spi/spi-s3c64xx.c | 12 ++++++++++++
> >>  1 file changed, 12 insertions(+)
> >
> > Oh, come on, stop fixing the same local issue without fixing bigger
> > picture... or at least documenting why bigger picture does not have to be
> > fixed and simple 'return' is enough.
> >
> > That's the third, same fix for the same problem.
> >
> > https://lore.kernel.org/lkml/20190314064202.14864-1-kjlu@umn.edu/
> > https://lore.kernel.org/lkml/20170207204520.h2eo3yn5kge56lk7@kozik-lap/
> 
> No wonder. There is a possible NULL dereference below. Now at least we
> know something about conditions that led to this.
> 
> Should I drop the entire patch, or just the dmaengine_prep_slave_sg() part?

The best would be to really go through the call stack and handle the
error properly.

This means returning an error code and propagating it further. It is not
a trivial change...

Best regards,
Krzysztof