2022-11-18 04:07:10

by Kees Cook

Subject: [PATCH v2 1/2] slab: Clean up SLOB vs kmalloc() definition

As already done for kmalloc_node(), clean up the #ifdef usage in the
definition of kmalloc() so that the SLOB-only version is an entirely
separate and much more readable function.

Cc: Vlastimil Babka <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
include/linux/slab.h | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 1c670c16c737..9033937c758e 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -558,15 +558,15 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align
* Try really hard to succeed the allocation but fail
* eventually.
*/
+#ifndef CONFIG_SLOB
static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
-#ifndef CONFIG_SLOB
unsigned int index;
-#endif
+
if (size > KMALLOC_MAX_CACHE_SIZE)
return kmalloc_large(size, flags);
-#ifndef CONFIG_SLOB
+
index = kmalloc_index(size);

if (!index)
@@ -575,10 +575,18 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
return kmalloc_trace(
kmalloc_caches[kmalloc_type(flags)][index],
flags, size);
-#endif
}
return __kmalloc(size, flags);
}
+#else
+static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
+{
+ if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
+ return kmalloc_large(size, flags);
+
+ return __kmalloc(size, flags);
+}
+#endif

#ifndef CONFIG_SLOB
static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
--
2.34.1

2022-11-18 12:10:04

by Hyeonggon Yoo

Subject: Re: [PATCH v2 1/2] slab: Clean up SLOB vs kmalloc() definition

On Thu, Nov 17, 2022 at 07:51:58PM -0800, Kees Cook wrote:
> As already done for kmalloc_node(), clean up the #ifdef usage in the
> definition of kmalloc() so that the SLOB-only version is an entirely
> separate and much more readable function.
>
> Cc: Vlastimil Babka <[email protected]>
> Cc: Christoph Lameter <[email protected]>
> Cc: Pekka Enberg <[email protected]>
> Cc: David Rientjes <[email protected]>
> Cc: Joonsoo Kim <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Roman Gushchin <[email protected]>
> Cc: Hyeonggon Yoo <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> include/linux/slab.h | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 1c670c16c737..9033937c758e 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -558,15 +558,15 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align
> * Try really hard to succeed the allocation but fail
> * eventually.
> */
> +#ifndef CONFIG_SLOB
> static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
> {
> if (__builtin_constant_p(size)) {
> -#ifndef CONFIG_SLOB
> unsigned int index;
> -#endif
> +
> if (size > KMALLOC_MAX_CACHE_SIZE)
> return kmalloc_large(size, flags);
> -#ifndef CONFIG_SLOB
> +
> index = kmalloc_index(size);
>
> if (!index)
> @@ -575,10 +575,18 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
> return kmalloc_trace(
> kmalloc_caches[kmalloc_type(flags)][index],
> flags, size);
> -#endif
> }
> return __kmalloc(size, flags);
> }
> +#else
> +static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
> +{
> + if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
> + return kmalloc_large(size, flags);
> +
> + return __kmalloc(size, flags);
> +}
> +#endif
>
> #ifndef CONFIG_SLOB
> static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
> --
> 2.34.1

Reviewed-by: Hyeonggon Yoo <[email protected]>

--
Thanks,
Hyeonggon