mm/slab: One function call less in verify_redzone_free()

Commit Message

Markus Elfring July 5, 2019, 2:50 p.m. UTC

From: Markus Elfring <[e-mail]>
Date: Fri, 5 Jul 2019 16:40:09 +0200

Avoid an extra function call by using a ternary operator instead of
a conditional statement for a string literal selection.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <[e-mail]>
---
 mm/slab.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--
2.22.0

Comments

Christoph Lameter (Ampere) July 5, 2019, 6:13 p.m. UTC | #1

On Fri, 5 Jul 2019, Markus Elfring wrote:

> Avoid an extra function call by using a ternary operator instead of
> a conditional statement for a string literal selection.

Well. I thought the compiler does that on its own? And the tenary operator
makes the code difficult to read.

David Rientjes July 6, 2019, 10:45 p.m. UTC | #2

On Fri, 5 Jul 2019, Christopher Lameter wrote:

> On Fri, 5 Jul 2019, Markus Elfring wrote:
> 
> > Avoid an extra function call by using a ternary operator instead of
> > a conditional statement for a string literal selection.
> 
> Well. I thought the compiler does that on its own? And the tenary operator
> makes the code difficult to read.
> 

Right, and I don't understand the changelog: yes, there's one less 
function call in the source but functionally there's still a conditional; 
this isn't even optimizing DEBUG builds.

Patch

diff --git a/mm/slab.c b/mm/slab.c
index 9df370558e5d..849b5c276588 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2701,10 +2701,10 @@  static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
 	if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
 		return;

-	if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
-		slab_error(cache, "double free detected");
-	else
-		slab_error(cache, "memory outside object was overwritten");
+	slab_error(cache,
+		   redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE
+		   ? "double free detected"
+		   : "memory outside object was overwritten");

 	pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
 	       obj, redzone1, redzone2);