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>

1 files changed, 6 insertions, 6 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index b130304f9b1bb..ca90ad8bcd619 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -609,14 +609,14 @@ typedef int (*dr_match_t)(struct device *dev, void *res, void *match_data);
 
 #ifdef CONFIG_DEBUG_DEVRES
 extern void *__devres_alloc_node(dr_release_t release, size_t size, gfp_t gfp,
-				 int nid, const char *name);
+				 int nid, const char *name) __malloc;
 #define devres_alloc(release, size, gfp) \
 	__devres_alloc_node(release, size, gfp, NUMA_NO_NODE, #release)
 #define devres_alloc_node(release, size, gfp, nid) \
 	__devres_alloc_node(release, size, gfp, nid, #release)
 #else
 extern void *devres_alloc_node(dr_release_t release, size_t size, gfp_t gfp,
-			       int nid);
+			       int nid) __malloc;
 static inline void *devres_alloc(dr_release_t release, size_t size, gfp_t gfp)
 {
 	return devres_alloc_node(release, size, gfp, NUMA_NO_NODE);
@@ -648,12 +648,12 @@ extern void devres_remove_group(struct device *dev, void *id);
 extern int devres_release_group(struct device *dev, void *id);
 
 /* managed devm_k.alloc/kfree for device drivers */
-extern void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp);
+extern void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __malloc;
 extern __printf(3, 0)
 char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt,
-		      va_list ap);
+		      va_list ap) __malloc;
 extern __printf(3, 4)
-char *devm_kasprintf(struct device *dev, gfp_t gfp, const char *fmt, ...);
+char *devm_kasprintf(struct device *dev, gfp_t gfp, const char *fmt, ...) __malloc;
 static inline void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
 {
 	return devm_kmalloc(dev, size, gfp | __GFP_ZERO);
@@ -671,7 +671,7 @@ static inline void *devm_kcalloc(struct device *dev,
 	return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
 }
 extern void devm_kfree(struct device *dev, void *p);
-extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp);
+extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp) __malloc;
 extern void *devm_kmemdup(struct device *dev, const void *src, size_t len,
 			  gfp_t gfp);