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>
diff --git a/include/linux/string.h b/include/linux/string.h
index d3993a7..26b6f6a 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -119,7 +119,7 @@
extern void kfree_const(const void *x);
-extern char *kstrdup(const char *s, gfp_t gfp);
+extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
extern const char *kstrdup_const(const char *s, gfp_t gfp);
extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
extern void *kmemdup(const void *src, size_t len, gfp_t gfp);