linux-kernel - Re: [PATCH 6/9] printk/nbcon: use panic_on_this

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Message-ID: <84wm6rbucz.fsf@jogness.linutronix.de>
Date: Mon, 25 Aug 2025 11:59:16 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Jinchao Wang <wangjinchao600@...il.com>, pmladek@...e.com,
 akpm@...ux-foundation.org, Steven Rostedt <rostedt@...dmis.org>, 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: Re: [PATCH 6/9] printk/nbcon: use panic_on_this_cpu() helper

On 2025-08-20, Jinchao Wang <wangjinchao600@...il.com> wrote:
> nbcon_context_try_acquire() compared
> panic_cpu directly with smp_processor_id().
> This open-coded check is now provided by
> panic_on_this_cpu().
>
> Switch to panic_on_this_cpu() to simplify
> the code and improve readability.
>
> Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
> ---
>  kernel/printk/nbcon.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
> index 646801813415..7490865e2f44 100644
> --- a/kernel/printk/nbcon.c
> +++ b/kernel/printk/nbcon.c
> @@ -2,6 +2,7 @@
>  // Copyright (C) 2022 Linutronix GmbH, John Ogness
>  // Copyright (C) 2022 Intel, Thomas Gleixner
>  
> +#include "linux/panic.h"
>  #include <linux/atomic.h>
>  #include <linux/bug.h>
>  #include <linux/console.h>

Please use angle brackets. Also, the includes are sorted
alphabetically. So it should look like this:

 #include <linux/irqflags.h>
 #include <linux/kthread.h>
 #include <linux/minmax.h>
+#include <linux/panic.h>
 #include <linux/percpu.h>
 #include <linux/preempt.h>
 #include <linux/slab.h>

> @@ -589,7 +590,6 @@ static struct printk_buffers panic_nbcon_pbufs;
>   */
>  static bool nbcon_context_try_acquire(struct nbcon_context *ctxt, bool is_reacquire)
>  {
> -	unsigned int cpu = smp_processor_id();
>  	struct console *con = ctxt->console;
>  	struct nbcon_state cur;
>  	int err;
> @@ -614,7 +614,7 @@ static bool nbcon_context_try_acquire(struct nbcon_context *ctxt, bool is_reacqu
>  	/* Acquire succeeded. */
>  
>  	/* Assign the appropriate buffer for this context. */
> -	if (atomic_read(&panic_cpu) == cpu)
> +	if (panic_on_this_cpu())
>  		ctxt->pbufs = &panic_nbcon_pbufs;
>  	else
>  		ctxt->pbufs = con->pbufs;

With the above changes:

Reviewed-by: John Ogness <john.ogness@...utronix.de>