linux-kernel - Re: [PATCH v4 1/4] devres: Provide krealloc

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Message-ID: <2023051530-immunize-pony-49ef@gregkh>
Date:   Mon, 15 May 2023 13:55:16 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     James Clark <james.clark@....com>
Cc:     linux-kernel@...r.kernel.org, linux@...ck-us.net,
        michal.simek@....com, Jonathan.Cameron@...wei.com,
        Jonathan Corbet <corbet@....net>,
        Jean Delvare <jdelvare@...e.com>,
        Anand Ashok Dumbre <anand.ashok.dumbre@...inx.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-doc@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v4 1/4] devres: Provide krealloc_array

On Mon, May 15, 2023 at 08:55:33AM +0100, James Clark wrote:
> 
> 
> On 13/05/2023 12:04, Greg KH wrote:
> > On Tue, May 09, 2023 at 10:49:38AM +0100, James Clark wrote:
> >> There is no krealloc_array equivalent in devres. Users would have to
> >> do their own multiplication overflow check so provide one.
> >>
> >> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> >> Signed-off-by: James Clark <james.clark@....com>
> >> ---
> >>  Documentation/driver-api/driver-model/devres.rst |  1 +
> >>  include/linux/device.h                           | 11 +++++++++++
> >>  2 files changed, 12 insertions(+)
> >>
> >> diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
> >> index 4249eb4239e0..8be086b3f829 100644
> >> --- a/Documentation/driver-api/driver-model/devres.rst
> >> +++ b/Documentation/driver-api/driver-model/devres.rst
> >> @@ -364,6 +364,7 @@ MEM
> >>    devm_kmalloc_array()
> >>    devm_kmemdup()
> >>    devm_krealloc()
> >> +  devm_krealloc_array()
> >>    devm_kstrdup()
> >>    devm_kstrdup_const()
> >>    devm_kvasprintf()
> >> diff --git a/include/linux/device.h b/include/linux/device.h
> >> index 472dd24d4823..58f4f5948edb 100644
> >> --- a/include/linux/device.h
> >> +++ b/include/linux/device.h
> >> @@ -223,6 +223,17 @@ static inline void *devm_kcalloc(struct device *dev,
> >>  {
> >>  	return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
> >>  }
> >> +static inline __realloc_size(3, 4) void * __must_check
> > 
> > Shouldn't you have a blank line before this one?
> 
> I was going for consistency with the rest of this section which doesn't
> have newlines between the functions for some reason. I can add one and
> resubmit but it might look a bit out of place?

Ah, wasn't aware of that, given the lack of context.  So nevermind, it's
fine for now.

> >> +devm_krealloc_array(struct device *dev, void *p, size_t new_n, size_t new_size, gfp_t flags)
> >> +{
> >> +	size_t bytes;
> >> +
> >> +	if (unlikely(check_mul_overflow(new_n, new_size, &bytes)))
> >> +		return NULL;
> >> +
> >> +	return devm_krealloc(dev, p, bytes, flags);
> >> +}
> > 
> > I dislike how we have to keep copying the "real" functions (i.e.
> > krealloc_array) into something like this, but I can't think of a better
> > way to do it.
> > 
> 
> Maybe something could be done with some macro magic, but it would
> probably end up being worse than just copying them and would affect the
> real ones as well. So yeah I can't think of any easy gains either.

Ok, that's good.  Given a lack of objections from others, I'll just take
this through my driver core tree in a few days.

thanks,

greg k-h