linux-kernel - [PATCH 7/9] panic/printk: replace this_cpu_in_panic() with panic_on_this

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Message-ID: <20250820091702.512524-8-wangjinchao600@gmail.com>
Date: Wed, 20 Aug 2025 17:14:52 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: pmladek@...e.com,
	akpm@...ux-foundation.org,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Feng Tang <feng.tang@...ux.alibaba.com>,
	Joel Granados <joel.granados@...nel.org>,
	Jinchao Wang <wangjinchao600@...il.com>,
	Nam Cao <namcao@...utronix.de>,
	Sravan Kumar Gundu <sravankumarlpu@...il.com>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 7/9] panic/printk: replace this_cpu_in_panic() with panic_on_this_cpu()

The helper this_cpu_in_panic() duplicated
logic already provided by panic_on_this_cpu().

Remove this_cpu_in_panic() and switch all
users to panic_on_this_cpu().

This simplifies the code and avoids having
two helpers for the same check.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 include/linux/printk.h            |  2 --
 kernel/panic.c                    |  2 +-
 kernel/printk/nbcon.c             |  2 +-
 kernel/printk/printk.c            | 15 ++-------------
 kernel/printk/printk_ringbuffer.c |  2 +-
 lib/dump_stack.c                  |  2 +-
 6 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 5d22b803f51e..45c663124c9b 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -330,8 +330,6 @@ static inline bool pr_flush(int timeout_ms, bool reset_on_progress)
 
 #endif
 
-bool this_cpu_in_panic(void);
-
 #ifdef CONFIG_SMP
 extern int __printk_cpu_sync_try_get(void);
 extern void __printk_cpu_sync_wait(void);
diff --git a/kernel/panic.c b/kernel/panic.c
index 5266e195f5ac..8415e4073da1 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -343,7 +343,7 @@ EXPORT_SYMBOL(panic_on_this_cpu);
  */
 bool panic_on_other_cpu(void)
 {
-	return (panic_in_progress() && !this_cpu_in_panic());
+	return (panic_in_progress() && !panic_on_this_cpu());
 }
 EXPORT_SYMBOL(panic_on_other_cpu);
 
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index 7490865e2f44..c6d1a4a747e9 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -1394,7 +1394,7 @@ enum nbcon_prio nbcon_get_default_prio(void)
 {
 	unsigned int *cpu_emergency_nesting;
 
-	if (this_cpu_in_panic())
+	if (panic_on_this_cpu())
 		return NBCON_PRIO_PANIC;
 
 	cpu_emergency_nesting = nbcon_get_cpu_emergency_nesting();
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5fe35f377b79..faa8b1f0585b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -17,6 +17,7 @@
  *	01Mar01 Andrew Morton
  */
 
+#include "linux/panic.h"
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/kernel.h>
@@ -345,18 +346,6 @@ static void __up_console_sem(unsigned long ip)
 }
 #define up_console_sem() __up_console_sem(_RET_IP_)
 
-/* Return true if a panic is in progress on the current CPU. */
-bool this_cpu_in_panic(void)
-{
-	/*
-	 * We can use raw_smp_processor_id() here because it is impossible for
-	 * the task to be migrated to the panic_cpu, or away from it. If
-	 * panic_cpu has already been set, and we're not currently executing on
-	 * that CPU, then we never will be.
-	 */
-	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
-}
-
 /*
  * Return true if a panic is in progress on a remote CPU.
  *
@@ -365,7 +354,7 @@ bool this_cpu_in_panic(void)
  */
 bool other_cpu_in_panic(void)
 {
-	return (panic_in_progress() && !this_cpu_in_panic());
+	return (panic_in_progress() && !panic_on_this_cpu());
 }
 
 /*
diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
index d9fb053cff67..e2a1b2d34d2b 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -2143,7 +2143,7 @@ static bool _prb_read_valid(struct printk_ringbuffer *rb, u64 *seq,
 			 * But it would have the sequence number returned
 			 * by "prb_next_reserve_seq() - 1".
 			 */
-			if (this_cpu_in_panic() &&
+			if (panic_on_this_cpu() &&
 			    (!debug_non_panic_cpus || legacy_allow_panic_sync) &&
 			    ((*seq + 1) < prb_next_reserve_seq(rb))) {
 				(*seq)++;
diff --git a/lib/dump_stack.c b/lib/dump_stack.c
index b3a85fe8b673..f0c78b5b5324 100644
--- a/lib/dump_stack.c
+++ b/lib/dump_stack.c
@@ -102,7 +102,7 @@ static void __dump_stack(const char *log_lvl)
  */
 asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
 {
-	bool in_panic = this_cpu_in_panic();
+	bool in_panic = panic_on_this_cpu();
 	unsigned long flags;
 
 	/*
-- 
2.43.0