Re: [PATCH v4 2/2] slab: Introduce kmalloc_obj() and family

[Kees Cook <kees@kernel.org>]

On Sat, Mar 15, 2025 at 03:48:30PM +1030, Gustavo A. R. Silva wrote:
> 
> > These each return the assigned value of ptr (which may be NULL on
> > failure). For cases where the total size of the allocation is needed,
> > the kmalloc_obj_sz(), kmalloc_objs_sz(), and kmalloc_flex_sz() family
> > of macros can be used. For example:
> > 
> > 	info->size = struct_size(ptr, flex_member, count);
> > 	ptr = kmalloc(info->size, gfp);
> > 
> > becomes:
> > 
> > 	kmalloc_flex_sz(ptr, flex_member, count, gfp, &info->size);
> 
> I wonder if it'd be better to keep the gfp flags as the last argument
> for all these `*_sz()` cases:
> 
> 	kmalloc_flex_sz(ptr, flex_member, count, &info->size, gpf);
> 
> Probably, even for __alloc_objs()

I was following the pattern of the other "alternative helpers", like
kmalloc_node(), which adds the additional argument to the end. I have no
real opinion about it, so I defer to the slab developers. :)

-Kees

-- 
Kees Cook