linux-kernel - [PATCH v2] mm/slub: Refactor note_cmpxchg

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Message-ID: <20250908094251.1080646-1-ye.liu@linux.dev>
Date: Mon,  8 Sep 2025 17:42:51 +0800
From: Ye Liu <ye.liu@...ux.dev>
To: Vlastimil Babka <vbabka@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: Ye Liu <liuye@...inos.cn>,
	Christoph Lameter <cl@...two.org>,
	David Rientjes <rientjes@...gle.com>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Harry Yoo <harry.yoo@...cle.com>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] mm/slub: Refactor note_cmpxchg_failure for better readability

From: Ye Liu <liuye@...inos.cn>

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

Signed-off-by: Ye Liu <liuye@...inos.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