linux-kernel - Re: [PATCH printk v1 02/13] printk: cpu sync always disable interrupts

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Message-ID: <YgZdjl0C4tPaZJkH@alley>
Date:   Fri, 11 Feb 2022 13:58:54 +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 v1 02/13] printk: cpu sync always disable
 interrupts

On Mon 2022-02-07 20:49:12, John Ogness wrote:
> The CPU sync functions are a NOP for !CONFIG_SMP. But for
> !CONFIG_SMP they still need to disable interrupts in order to
> preserve context within the CPU sync sections.
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

Good catch!

It is interesting that the original code did not disable interrupts
around __dump_stack() on non-SMP, see the commit 766c268bc6d39b8124
("lib/dump_stack: move cpu lock to printk.c"). But it was rather
a bug. The patch makes perfect sense.

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

Best Regards,
Petr