linux-kernel - Re: [PATCH printk v2 18/26] printk: nbcon: Add unsafe flushing on panic

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Message-ID: <ZeCMX2udjcxGLDtd@alley>
Date: Thu, 29 Feb 2024 14:53:35 +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,
	Andrew Morton <akpm@...ux-foundation.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Uros Bizjak <ubizjak@...il.com>,
	"Guilherme G. Piccoli" <gpiccoli@...lia.com>,
	Lukas Wunner <lukas@...ner.de>, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH printk v2 18/26] printk: nbcon: Add unsafe flushing on
 panic

On Sun 2024-02-18 20:03:18, John Ogness wrote:
> Add nbcon_atomic_flush_unsafe() to flush all nbcon consoles
> using the write_atomic() callback and allowing unsafe hostile
> takeovers. Call this at the end of panic() as a final attempt
> to flush any pending messages.
> 
> Note that legacy consoles use unsafe methods for flushing
> from the beginning of panic (see bust_spinlocks()). Therefore,
> systems using both legacy and nbcon consoles may still fail to
> see panic messages due to unsafe legacy console usage.
> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

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

Best Regards,
Petr