Re: [PATCH v2 1/8] mm: slab: provide krealloc_array()

Re: [PATCH v2 1/8] mm: slab: provide krealloc_array()

[Matthew Wilcox]

On Mon, Nov 02, 2020 at 04:20:30PM +0100, Bartosz Golaszewski wrote:
> +Chunks allocated with `kmalloc` can be resized with `krealloc`. Similarly
> +to `kmalloc_array`: a helper for resising arrays is provided in the form of
> +`krealloc_array`.

Is there any reason you chose to `do_this` instead of do_this()?  The
automarkup script turns do_this() into a nice link to the documentation
which you're adding below.

Typo 'resising' resizing.
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Re: [PATCH v2 8/8] dma-buf: use krealloc_array()

[Andy Shevchenko]

On Mon, Nov 02, 2020 at 04:20:37PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Use the helper that checks for overflows internally instead of manually
> calculating the size of the new array.

...

> +		nfences = krealloc_array(fences, i,
> +					 sizeof(*fences), GFP_KERNEL);

On 80 position is closing parenthesis, which, I think, makes it okay to put on
one line.

-- 
With Best Regards,
Andy Shevchenko


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Re: [PATCH v2 0/8] slab: provide and use krealloc_array()

[Joe Perches]

On Mon, 2020-11-02 at 16:20 +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Andy brought to my attention the fact that users allocating an array of
> equally sized elements should check if the size multiplication doesn't
> overflow. This is why we have helpers like kmalloc_array().
> 
> However we don't have krealloc_array() equivalent and there are many
> users who do their own multiplication when calling krealloc() for arrays.
> 
> This series provides krealloc_array() and uses it in a couple places.

My concern about this is a possible assumption that __GFP_ZERO will
work, and as far as I know, it will not.


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Re: [PATCH v2 0/8] slab: provide and use krealloc_array()

[Andy Shevchenko]

On Tue, Nov 3, 2020 at 12:13 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> On Tue, Nov 3, 2020 at 5:14 AM Joe Perches <joe@perches.com> wrote:
> > On Mon, 2020-11-02 at 16:20 +0100, Bartosz Golaszewski wrote:
> > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

> Yeah so I had this concern for devm_krealloc() and even sent a patch
> that extended it to honor __GFP_ZERO before I noticed that regular
> krealloc() silently ignores __GFP_ZERO. I'm not sure if this is on
> purpose. Maybe we should either make krealloc() honor __GFP_ZERO or
> explicitly state in its documentation that it ignores it?

And my voice here is to ignore for the same reasons: respect
realloc(3) and making common sense with the idea of REallocating
(capital letters on purpose).

-- 
With Best Regards,
Andy Shevchenko
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