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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2016-05-20 03:10:55 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 05:12:14 +0300
commit48a270554a3251681ae11173f2fd6389d943e183 (patch)
treeb650279a0e0c255f28ad819593a3c86328821571 /include/linux/kernel.h
parentd64e85d3e1c59c3664b9ec1183052ec4641ea1e2 (diff)
downloadlinux-48a270554a3251681ae11173f2fd6389d943e183.tar.xz
include/linux: apply __malloc attribute
Attach the malloc attribute to a few allocation functions. This helps gcc generate better code by telling it that the return value doesn't alias any existing pointers (which is even more valuable given the pessimizations implied by -fno-strict-aliasing). A simple example of what this allows gcc to do can be seen by looking at the last part of drm_atomic_helper_plane_reset: plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL); if (plane->state) { plane->state->plane = plane; plane->state->rotation = BIT(DRM_ROTATE_0); } which compiles to e8 99 bf d6 ff callq ffffffff8116d540 <kmem_cache_alloc_trace> 48 85 c0 test %rax,%rax 48 89 83 40 02 00 00 mov %rax,0x240(%rbx) 74 11 je ffffffff814015c4 <drm_atomic_helper_plane_reset+0x64> 48 89 18 mov %rbx,(%rax) 48 8b 83 40 02 00 00 mov 0x240(%rbx),%rax [*] c7 40 40 01 00 00 00 movl $0x1,0x40(%rax) With this patch applied, the instruction at [*] is elided, since the store to plane->state->plane is known to not alter the value of plane->state. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> 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: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/kernel.h')
-rw-r--r--include/linux/kernel.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2f7775e229b0..cc7398287fdd 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -412,9 +412,9 @@ extern __printf(3, 4)
int scnprintf(char *buf, size_t size, const char *fmt, ...);
extern __printf(3, 0)
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
-extern __printf(2, 3)
+extern __printf(2, 3) __malloc
char *kasprintf(gfp_t gfp, const char *fmt, ...);
-extern __printf(2, 0)
+extern __printf(2, 0) __malloc
char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
extern __printf(2, 0)
const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);