[v2] mm/slub: Refactor note_cmpxchg_failure for better readability

[PATCH v2] mm/slub: Refactor note_cmpxchg_failure for better readability

Posted by Ye Liu 3 weeks, 3 days ago

From: Ye Liu <liuye@kylinos.cn>

Use IS_ENABLED() and standard if-else to make the code clearer.

Signed-off-by: Ye Liu <liuye@kylinos.cn>

Changes in v2:
- Insert newline after && as it's more than 80 columns.
---
 mm/slub.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 30003763d224..5711d6d29a3f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3064,18 +3064,17 @@ static inline void note_cmpxchg_failure(const char *n,
 
 	pr_info("%s %s: cmpxchg redo ", n, s->name);
 
-#ifdef CONFIG_PREEMPTION
-	if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
+	if (IS_ENABLED(CONFIG_PREEMPTION) &&
+	    tid_to_cpu(tid) != tid_to_cpu(actual_tid)) {
 		pr_warn("due to cpu change %d -> %d\n",
 			tid_to_cpu(tid), tid_to_cpu(actual_tid));
-	else
-#endif
-	if (tid_to_event(tid) != tid_to_event(actual_tid))
+	} else if (tid_to_event(tid) != tid_to_event(actual_tid)) {
 		pr_warn("due to cpu running other code. Event %ld->%ld\n",
 			tid_to_event(tid), tid_to_event(actual_tid));
-	else
+	} else {
 		pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
 			actual_tid, tid, next_tid(tid));
+	}
 #endif
 	stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
 }
-- 
2.43.0

Re: [PATCH v2] mm/slub: Refactor note_cmpxchg_failure for better readability

Posted by Harry Yoo 3 weeks, 3 days ago

On Mon, Sep 08, 2025 at 05:42:51PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye@kylinos.cn>
> 
> Use IS_ENABLED() and standard if-else to make the code clearer.
> 
> Signed-off-by: Ye Liu <liuye@kylinos.cn>
> 
> Changes in v2:
> - Insert newline after && as it's more than 80 columns.

nit: This is not where patch vX -> vY change log goes.

> ---

It should be below '---' line because it's not useful to add that
to git history.

Other than that, LGTM:
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>

>  mm/slub.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 30003763d224..5711d6d29a3f 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3064,18 +3064,17 @@ static inline void note_cmpxchg_failure(const char *n,
>  
>  	pr_info("%s %s: cmpxchg redo ", n, s->name);
>  
> -#ifdef CONFIG_PREEMPTION
> -	if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
> +	if (IS_ENABLED(CONFIG_PREEMPTION) &&
> +	    tid_to_cpu(tid) != tid_to_cpu(actual_tid)) {
>  		pr_warn("due to cpu change %d -> %d\n",
>  			tid_to_cpu(tid), tid_to_cpu(actual_tid));
> -	else
> -#endif
> -	if (tid_to_event(tid) != tid_to_event(actual_tid))
> +	} else if (tid_to_event(tid) != tid_to_event(actual_tid)) {
>  		pr_warn("due to cpu running other code. Event %ld->%ld\n",
>  			tid_to_event(tid), tid_to_event(actual_tid));
> -	else
> +	} else {
>  		pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
>  			actual_tid, tid, next_tid(tid));
> +	}
>  #endif
>  	stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
>  }
> -- 
> 2.43.0
> 
> 

-- 
Cheers,
Harry / Hyeonggon