linux-kernel - Re: [PATCH linux-next] printk: nbcon: Fix nbcon_cpu_emergency

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Message-ID: <ZmA5oIkImclKM0vx@pathway.suse.cz>
Date: Wed, 5 Jun 2024 12:10:40 +0200
From: Petr Mladek <pmladek@...e.com>
To: John Ogness <john.ogness@...utronix.de>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Juri Lelli <juri.lelli@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH linux-next] printk: nbcon: Fix
 nbcon_cpu_emergency_flush() when preemptible

On Wed 2024-06-05 11:57:34, John Ogness wrote:
> nbcon_cpu_emergency_flush() can be called in a preemptible
> context. In that case the CPU is not in an emergency state.
> However, in order to see that the CPU is not in an emergency
> state (accessing the per-cpu variable), preemption must be
> disabled.
> 
> Disable preemption when checking the CPU state.
> 
> Reported-by: Juri Lelli <juri.lelli@...hat.com>
> Closes: https://lore.kernel.org/aqkcpca4vgadxc3yzcu74xwq3grslj5m43f3eb5fcs23yo2gy4@gcsnqcts5tos
> Fixes: 46a1379208b7 ("printk: nbcon: Implement emergency sections")
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

Great catch!

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

I am going to push it...

Best Regards,
Petr