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

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Date:   Tue, 27 Oct 2020 19:20:06 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        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>
Cc:     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 10/27/20 1:17 PM, 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>

Makes sense.
Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>   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);
>   }
>   
> +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.
>