linux-kernel - Re: [PATCH v2 1/4] device: provide devm_krealloc

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Date:   Mon, 16 Nov 2020 11:18:03 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Michal Simek <michal.simek@...inx.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/4] device: provide devm_krealloc_array()

On Sat, Nov 14, 2020 at 5:16 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Sat, Nov 14, 2020 at 03:46:41PM +0000, Jonathan Cameron wrote:
> > On Mon,  2 Nov 2020 15:22:25 +0100
> > Bartosz Golaszewski <brgl@...ev.pl> wrote:
> >
> > > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> > >
> > > When allocating an array of elements, users should check for
> > > multiplication overflow or preferably use one of the provided helpers
> > > like: devm_kmalloc_array().
> > >
> > > This provides devm_krealloc_array() for users who want to reallocate
> > > managed arrays.
> > >
> > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > +CC Greg KH.
> >
> > As this is going into a very generic place I'd like a relevant ack.
> > That file is a bit of a wild west for acks, but Greg seems most
> > appropriate person.
> >
> > So Greg, any comments on this one?
>
> As there is only 1 user of this function in the patch series, you don't
> save any extra code space here, I don't think this is worth it.
>

It's worth it in that the overflow check before allocation doesn't
seem to belong in a driver IMO but is a general check that should live
in common code.

> We are seeing less and less gains from these new devm_* additions, and
> only more confusion and problems with them.  So perhaps don't add this?
> I don't think it is needed.
>

I think you're referring to the discussion on
devm_platform_ioremap_resource()? I would argue that consolidation of
common operations in helpers is rarely a bad thing but it's a
discussion for another thread.

I'm not too attached to this patch - if you think this should be
dropped then fine, but I don't see how the name devm_krealloc_array()
can confuse anyone.

Bartosz