linux-kernel - Re: [PATCH printk v4 14/14] dump_stack: Do not get cpu

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Date: Wed, 7 Feb 2024 17:16:18 +0100
From: Petr Mladek <pmladek@...e.com>
To: John Ogness <john.ogness@...utronix.de>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH printk v4 14/14] dump_stack: Do not get cpu_sync for
 panic CPU

On Wed 2024-02-07 14:47:03, John Ogness wrote:
> dump_stack() is called in panic(). If for some reason another CPU
> is holding the printk_cpu_sync and is unable to release it, the
> panic CPU will be unable to continue and print the stacktrace.
> 
> Since non-panic CPUs are not allowed to store new printk messages
> anyway, there is no need to synchronize the stacktrace output in
> a panic situation.
> 
> For the panic CPU, do not get the printk_cpu_sync because it is
> not needed and avoids a potential deadlock scenario in panic().
> 
> Link: https://lore.kernel.org/lkml/ZcIGKU8sxti38Kok@alley
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

Makes sense.

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr