Re: [Xen-devel] [PATCH V2 3/6] [RFC] xen/common: Introduce _xrealloc function

[Oleksandr <olekstysh@xxxxxxxxx>]

On 05.08.19 13:02, Jan Beulich wrote:

Hi, Jan

> While I can see why having a re-allocation function may be handy,
> explicit / direct use of _xmalloc() and _xzalloc() are discouraged,
> in favor of the more type-safe underscore-less variants.
took into account


> I can't
> see though how a type-safe "realloc" could look like, except for
> arrays. If resizing arrays is all you're after, I'd like to
> recommend to go that route rather then the suggested one here. If
> resizing arbitrary objects is the goal, then what you suggest may
> be the only route, but I'd still be not overly happy to see such
> added.
My main goal is to get "ported" from Linux "iommu_fwspec" support 
(xrealloc user) in [1].
I tried to retain code as much as possible while porting. So, this patch 
adds almost the same thing what the ported code expects.
But, I would be OK to consider modifying a code in a way to resize an 
array as well as any other variants if present.

> Furthermore you don't even use internals of the allocator: It is
> common practice to avoid re-allocation if the requested size fits
> within the already allocated block. That's not the least helpful
> because in such a case you can't possibly suffer any -ENOMEM
> condition.
agree, took into account as well.


> And finally - please note _xmalloc()'s and _xfree()'s use /
> special casing of ZERO_BLOCK_PTR: You absolutely would need to
> mirror this here.
got it, will use for zero-size allocation


[1] 
https://lists.xenproject.org/archives/html/xen-devel/2019-08/msg00257.html

Thank you.


--
Regards,

Oleksandr Tyshchenko


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