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| author | Kees Cook <keescook@chromium.org> | 2022-11-17 19:51:59 -0800 |
|---|---|---|
| committer | Vlastimil Babka <vbabka@suse.cz> | 2022-11-21 10:27:00 +0100 |
| commit | 6fa57d78aa7f212fd7c0de70f5756e18513dcdcf (patch) | |
| tree | f8cdf805bbacc1861a0eb35116582a55089b1c52 /include/linux/slab.h | |
| parent | 3bf019334fbbb51723587f9819c62d3d6f9d6f3f (diff) | |
| download | linux-6fa57d78aa7f212fd7c0de70f5756e18513dcdcf.tar.gz | |
slab: Remove special-casing of const 0 size allocations
Passing a constant-0 size allocation into kmalloc() or kmalloc_node()
does not need to be a fast-path operation, so the static return value
can be removed entirely. This makes sure that all paths through the
inlines result in a full extern function call, where __alloc_size()
hints will actually be seen[1] by GCC. (A constant return value of 0
means the "0" allocation size won't be propagated by the inline.)
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96503
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: linux-mm@kvack.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'include/linux/slab.h')
| -rw-r--r-- | include/linux/slab.h | 12 |
1 files changed, 2 insertions, 10 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h index 8a25d1b2e4203..134cc05e57453 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -539,17 +539,13 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align #ifndef CONFIG_SLOB static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags) { - if (__builtin_constant_p(size)) { + if (__builtin_constant_p(size) && size) { unsigned int index; if (size > KMALLOC_MAX_CACHE_SIZE) return kmalloc_large(size, flags); index = kmalloc_index(size); - - if (!index) - return ZERO_SIZE_PTR; - return kmalloc_trace( kmalloc_caches[kmalloc_type(flags)][index], flags, size); @@ -569,17 +565,13 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags) #ifndef CONFIG_SLOB static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node) { - if (__builtin_constant_p(size)) { + if (__builtin_constant_p(size) && size) { unsigned int index; if (size > KMALLOC_MAX_CACHE_SIZE) return kmalloc_large_node(size, flags, node); index = kmalloc_index(size); - - if (!index) - return ZERO_SIZE_PTR; - return kmalloc_node_trace( kmalloc_caches[kmalloc_type(flags)][index], flags, node, size); |