linux-kernel - Re: [PATCH 1/8] mm: slab: provide krealloc

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Date:   Wed, 28 Oct 2020 10:47:03 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Christian König <christian.koenig@....com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Robert Richter <rric@...nel.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
        linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        linux-gpio@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-mm@...ck.org, alsa-devel@...a-project.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH 1/8] mm: slab: provide krealloc_array()

On Tue, Oct 27, 2020 at 01:17:18PM +0100, Bartosz Golaszewski 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: kmalloc_array().
> 
> There's no krealloc_array() counterpart but there are many users who use
> regular krealloc() to reallocate arrays. Let's provide an actual
> krealloc_array() implementation.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> ---
>  include/linux/slab.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index dd6897f62010..0e6683affee7 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -592,6 +592,17 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
>  	return __kmalloc(bytes, flags);
>  }
>  

Can you please add kernel-doc here and a word or two about this function
to Documentation/core-api/memory-allocation.rst?

> +static __must_check inline void *
> +krealloc_array(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 krealloc(p, bytes, flags);
> +}
> +
>  /**
>   * kcalloc - allocate memory for an array. The memory is set to zero.
>   * @n: number of elements.
> -- 
> 2.29.1
> 
> 

-- 
Sincerely yours,
Mike.