linux-kernel - [PATCH v2 4/9] panic: use panic_try_start() in nmi

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Message-ID: <20250825022947.1596226-5-wangjinchao600@gmail.com>
Date: Mon, 25 Aug 2025 10:29:32 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Baoquan He <bhe@...hat.com>,
	Yury Norov <yury.norov@...il.com>,
	Qianqiang Liu <qianqiang.liu@....com>,
	Simona Vetter <simona@...ll.ch>,
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	John Ogness <john.ogness@...utronix.de>,
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	Dave Young <dyoung@...hat.com>,
	Kees Cook <kees@...nel.org>,
	Tony Luck <tony.luck@...el.com>,
	"Guilherme G. Piccoli" <gpiccoli@...lia.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Shixiong Ou <oushixiong@...inos.cn>,
	Jinchao Wang <wangjinchao600@...il.com>,
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	Ingo Molnar <mingo@...nel.org>,
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	Anna Schumaker <anna.schumaker@...cle.com>,
	"Darrick J. Wong" <djwong@...nel.org>,
	Max Kellermann <max.kellermann@...os.com>,
	Yunhui Cui <cuiyunhui@...edance.com>,
	Tejun Heo <tj@...nel.org>,
	Luo Gengkun <luogengkun@...weicloud.com>,
	Li Huafei <lihuafei1@...wei.com>,
	Thorsten Blum <thorsten.blum@...ux.dev>,
	Yicong Yang <yangyicong@...ilicon.com>,
	linux-fbdev@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	kexec@...ts.infradead.org,
	linux-hardening@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/9] panic: use panic_try_start() in nmi_panic()

nmi_panic() duplicated the logic to claim panic_cpu with atomic_try_cmpxchg.
This is already wrapped in panic_try_start().

Replace the open-coded logic with panic_try_start(), and use
panic_on_other_cpu() for the fallback path.

This removes duplication and keeps panic handling code consistent.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 kernel/panic.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index eacb0c972110..cd86d37d124c 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -355,15 +355,9 @@ EXPORT_SYMBOL(panic_on_other_cpu);
  */
 void nmi_panic(struct pt_regs *regs, const char *msg)
 {
-	int old_cpu, this_cpu;
-
-	old_cpu = PANIC_CPU_INVALID;
-	this_cpu = raw_smp_processor_id();
-
-	/* atomic_try_cmpxchg updates old_cpu on failure */
-	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu))
+	if (panic_try_start())
 		panic("%s", msg);
-	else if (old_cpu != this_cpu)
+	else if (panic_on_other_cpu())
 		nmi_panic_self_stop(regs);
 }
 EXPORT_SYMBOL(nmi_panic);
-- 
2.43.0