Duplicate kernel-doc comments for ksize()

Duplicate kernel-doc comments for ksize()

[Akira Yokosawa]

Hi Kees,

"make htmldocs" reports duplicate C declaration of ksize()
as follows:

/linux/Documentation/core-api/mm-api:43: ./mm/slab_common.c:1428: WARNING: Duplicate C declaration, also defined at core-api/mm-api:212.
Declaration is '.. c:function:: size_t ksize (const void *objp)'.

This is due to the kernel-doc comment for ksize() added in
include/linux/slab.h by a commit you have authored:
  05a940656e1e ("slab:Introduce kmalloc_size_roundup()").

/**
 * ksize - Report actual allocation size of associated object
 *
 * @objp: Pointer returned from a prior kmalloc()-family allocation.
 *
 * This should not be used for writing beyond the originally requested
 * allocation size. Either use krealloc() or round up the allocation size
 * with kmalloc_size_roundup() prior to allocation. If this is used to
 * access beyond the originally requested allocation size, UBSAN_BOUNDS
 * and/or FORTIFY_SOURCE may trip, since they only know about the
 * originally allocated size via the __alloc_size attribute.
 */

There is another kernel-doc comment in mm/slab_common.c (originally
by Manfred, since v2.6.14):

/**
 * ksize - get the actual amount of memory allocated for a given object
 * @objp: Pointer to the object
 *
 * kmalloc may internally round up allocations and return more memory
 * than requested. ksize() can be used to determine the actual amount of
 * memory allocated. The caller may use this additional memory, even though
 * a smaller amount of memory was initially specified with the kmalloc call.
 * The caller must guarantee that objp points to a valid object previously
 * allocated with either kmalloc() or kmem_cache_alloc(). The object
 * must not be freed during the duration of the call.
 *
 * Return: size of the actual memory used by @objp in bytes
 */

I guess the one in slab_common.c is outdated and can be removed.
Can you please take care of it?

        Thanks, Akira

Re: Duplicate kernel-doc comments for ksize()

[Vlastimil Babka]

On 11/7/22 11:41, Akira Yokosawa wrote:
> Hi Kees,
> 
> "make htmldocs" reports duplicate C declaration of ksize()
> as follows:
> 
> /linux/Documentation/core-api/mm-api:43: ./mm/slab_common.c:1428: WARNING: Duplicate C declaration, also defined at core-api/mm-api:212.
> Declaration is '.. c:function:: size_t ksize (const void *objp)'.
> 
> This is due to the kernel-doc comment for ksize() added in
> include/linux/slab.h by a commit you have authored:
>   05a940656e1e ("slab:Introduce kmalloc_size_roundup()").
> 
> /**
>  * ksize - Report actual allocation size of associated object
>  *
>  * @objp: Pointer returned from a prior kmalloc()-family allocation.
>  *
>  * This should not be used for writing beyond the originally requested
>  * allocation size. Either use krealloc() or round up the allocation size
>  * with kmalloc_size_roundup() prior to allocation. If this is used to
>  * access beyond the originally requested allocation size, UBSAN_BOUNDS
>  * and/or FORTIFY_SOURCE may trip, since they only know about the
>  * originally allocated size via the __alloc_size attribute.
>  */
> 
> There is another kernel-doc comment in mm/slab_common.c (originally
> by Manfred, since v2.6.14):
> 
> /**
>  * ksize - get the actual amount of memory allocated for a given object
>  * @objp: Pointer to the object
>  *
>  * kmalloc may internally round up allocations and return more memory
>  * than requested. ksize() can be used to determine the actual amount of
>  * memory allocated. The caller may use this additional memory, even though
>  * a smaller amount of memory was initially specified with the kmalloc call.
>  * The caller must guarantee that objp points to a valid object previously
>  * allocated with either kmalloc() or kmem_cache_alloc(). The object
>  * must not be freed during the duration of the call.
>  *
>  * Return: size of the actual memory used by @objp in bytes
>  */
> 
> I guess the one in slab_common.c is outdated and can be removed.
> Can you please take care of it?

Thanks for the report, I've removed the comment myself in a slab.git fixes
branch I'll be sending a PR for this week:

https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git/commit/?h=slab/for-6.1-rc4/fixes&id=c18c20f16219516b12a4f2fd29c25e06be97e064

>         Thanks, Akira