linux-kernel - [PATCH] lib/smp_processor_id: use preemptible() macro

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Message-ID: <225b0c28-8333-9849-0d7b-2a561fb20ccb@I-love.SAKURA.ne.jp>
Date:   Thu, 23 Jun 2022 23:18:54 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] lib/smp_processor_id: use preemptible() macro

preemptible() is unconditional 0 if CONFIG_PREEMPT_COUNT=n, and is
(preempt_count() == 0 && !irqs_disabled()) if CONFIG_PREEMPT_COUNT=y.

Although check_preemption_disabled() depends on CONFIG_PREEMPT_COUNT=y,
the naming implies whether preemption is already disabled. Thus, let's
make check_preemption_disabled() safe even if CONFIG_PREEMPT_COUNT=n.

Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 lib/smp_processor_id.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 046ac6297c78..5bb0783ce038 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -13,10 +13,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2)
 {
 	int this_cpu = raw_smp_processor_id();
 
-	if (likely(preempt_count()))
-		goto out;
-
-	if (irqs_disabled())
+	if (likely(!preemptible()))
 		goto out;
 
 	if (is_percpu_thread())
-- 
2.18.4