RE: [PATCH 1/2] mm: vmalloc: introduce array allocation functions

[David Laight <David.Laight@ACULAB.COM>]

From: oficerovas@altlinux.org
> Sent: 26 January 2024 09:55
> 
> commit a8749a35c399 ("mm: vmalloc: introduce array allocation functions")
> 
> Linux has dozens of occurrences of vmalloc(array_size()) and
> vzalloc(array_size()).  Allow to simplify the code by providing
> vmalloc_array and vcalloc, as well as the underscored variants that let
> the caller specify the GFP flags.
> 
> Acked-by: Michal Hocko <mhocko@suse.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Alexander Ofitserov <oficerovas@altlinux.org>
> ---
>  include/linux/vmalloc.h |  5 +++++
>  mm/util.c               | 50 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 55 insertions(+)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 76dad53a410ac..0fd47f2f39eb0 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -112,6 +112,11 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
>  void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
>  		int node, const void *caller);
> 
> +extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags);
> +extern void *vmalloc_array(size_t n, size_t size);
> +extern void *__vcalloc(size_t n, size_t size, gfp_t flags);
> +extern void *vcalloc(size_t n, size_t size);

Symbols starting __ should really be ones that are part of the implementation
and not publicly visible.

...
> +/**
> + * __vmalloc_array - allocate memory for a virtually contiguous array.
> + * @n: number of elements.
> + * @size: element size.
> + * @flags: the type of memory to allocate (see kmalloc).
> + */
> +void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
> +{
> +	size_t bytes;
> +
> +	if (unlikely(check_mul_overflow(n, size, &bytes)))
> +		return NULL;
> +	return __vmalloc(bytes, flags);
> +}
> +EXPORT_SYMBOL(__vmalloc_array);
> +
> +/**
> + * vmalloc_array - allocate memory for a virtually contiguous array.
> + * @n: number of elements.
> + * @size: element size.
> + */
> +void *vmalloc_array(size_t n, size_t size)
> +{
> +	return __vmalloc_array(n, size, GFP_KERNEL);
> +}
> +EXPORT_SYMBOL(vmalloc_array);

and that should just be an inline wrapper on the function above.

	David

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