linux-kernel - [PATCH 8/9] panic/printk: replace other_cpu_in_panic() with panic_on_other

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Message-ID: <20250820091702.512524-9-wangjinchao600@gmail.com>
Date: Wed, 20 Aug 2025 17:14:53 +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>
Cc: linux-kernel@...r.kernel.org,
	feng.tang@...ux.alibaba.com,
	joel.granados@...nel.org,
	wangjinchao600@...il.com,
	namcao@...utronix.de,
	sravankumarlpu@...il.com
Subject: [PATCH 8/9] panic/printk: replace other_cpu_in_panic() with panic_on_other_cpu()

The helper other_cpu_in_panic() duplicated
logic already provided by panic_on_other_cpu().

Remove other_cpu_in_panic() and update all
users to call panic_on_other_cpu() instead.

This removes redundant code and makes panic
handling consistent.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 kernel/printk/internal.h |  1 -
 kernel/printk/nbcon.c    |  8 ++++----
 kernel/printk/printk.c   | 19 ++++---------------
 3 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index ef282001f200..f72bbfa266d6 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -332,7 +332,6 @@ struct printk_message {
 	unsigned long		dropped;
 };
 
-bool other_cpu_in_panic(void);
 bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
 			     bool is_extended, bool may_supress);
 
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index c6d1a4a747e9..171480135830 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -255,7 +255,7 @@ static int nbcon_context_try_acquire_direct(struct nbcon_context *ctxt,
 		 * opportunity to perform any necessary cleanup if they were
 		 * interrupted by the panic CPU while printing.
 		 */
-		if (other_cpu_in_panic() &&
+		if (panic_on_other_cpu() &&
 		    (!is_reacquire || cur->unsafe_takeover)) {
 			return -EPERM;
 		}
@@ -310,7 +310,7 @@ static bool nbcon_waiter_matches(struct nbcon_state *cur, int expected_prio)
 	 * Event #2 implies the new context is PANIC.
 	 * Event #3 occurs when panic() has flushed the console.
 	 * Event #4 occurs when a non-panic CPU reacquires.
-	 * Event #5 is not possible due to the other_cpu_in_panic() check
+	 * Event #5 is not possible due to the panic_on_other_cpu() check
 	 *          in nbcon_context_try_acquire_handover().
 	 */
 
@@ -349,7 +349,7 @@ static int nbcon_context_try_acquire_requested(struct nbcon_context *ctxt,
 	struct nbcon_state new;
 
 	/* Note that the caller must still remove the request! */
-	if (other_cpu_in_panic())
+	if (panic_on_other_cpu())
 		return -EPERM;
 
 	/*
@@ -447,7 +447,7 @@ static int nbcon_context_try_acquire_handover(struct nbcon_context *ctxt,
 	 * nbcon_waiter_matches(). In particular, the assumption that
 	 * lower priorities are ignored during panic.
 	 */
-	if (other_cpu_in_panic())
+	if (panic_on_other_cpu())
 		return -EPERM;
 
 	/* Handover is not possible on the same CPU. */
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index faa8b1f0585b..236f03937107 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -346,17 +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 a remote CPU.
- *
- * On true, the local CPU should immediately release any printing resources
- * that may be needed by the panic CPU.
- */
-bool other_cpu_in_panic(void)
-{
-	return (panic_in_progress() && !panic_on_this_cpu());
-}
-
 /*
  * This is used for debugging the mess that is the VT code by
  * keeping track if we have the console semaphore held. It's
@@ -2391,7 +2380,7 @@ asmlinkage int vprintk_emit(int facility, int level,
 	 * non-panic CPUs are generating any messages, they will be
 	 * silently dropped.
 	 */
-	if (other_cpu_in_panic() &&
+	if (panic_on_other_cpu() &&
 	    !debug_non_panic_cpus &&
 	    !panic_triggering_all_cpu_backtrace)
 		return 0;
@@ -2827,7 +2816,7 @@ void console_lock(void)
 	might_sleep();
 
 	/* On panic, the console_lock must be left to the panic cpu. */
-	while (other_cpu_in_panic())
+	while (panic_on_other_cpu())
 		msleep(1000);
 
 	down_console_sem();
@@ -2847,7 +2836,7 @@ EXPORT_SYMBOL(console_lock);
 int console_trylock(void)
 {
 	/* On panic, the console_lock must be left to the panic cpu. */
-	if (other_cpu_in_panic())
+	if (panic_on_other_cpu())
 		return 0;
 	if (down_trylock_console_sem())
 		return 0;
@@ -3227,7 +3216,7 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove
 			any_progress = true;
 
 			/* Allow panic_cpu to take over the consoles safely. */
-			if (other_cpu_in_panic())
+			if (panic_on_other_cpu())
 				goto abandon;
 
 			if (do_cond_resched)
-- 
2.43.0