linux-kernel - Re: [PATCH printk v1] printk: Avoid irq_work for printk

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aSCLXbsuq2TKEz_u@pathway.suse.cz>
Date: Fri, 21 Nov 2025 16:55:09 +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>,
	Sherry Sun <sherry.sun@....com>, Jacky Bai <ping.bai@....com>,
	Jon Hunter <jonathanh@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Derek Barbosa <debarbos@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH printk v1] printk: Avoid irq_work for printk_deferred()
 on suspend

On Fri 2025-11-21 11:26:00, John Ogness wrote:
> With commit ("printk: Avoid scheduling irq_work on suspend") the
> implementation of printk_get_console_flush_type() was modified to
> avoid offloading when irq_work should be blocked during suspend.
> Since printk uses the returned flush type to determine what
> flushing methods are used, this was thought to be sufficient for
> avoiding irq_work usage during the suspend phase.
> 
> However, vprintk_emit() implements a hack to support
> printk_deferred(). In this hack, the returned flush type is
> adjusted to make sure no legacy direct printing occurs when
> printk_deferred() was used.
> 
> Because of this hack, the legacy offloading flushing method can
> still be used, causing irq_work to be queued when it should not
> be.
> 
> Adjust the vprintk_emit() hack to also consider
> @console_irqwork_blocked so that legacy offloading will not be
> chosen when irq_work should be blocked.
> 
> Link: https://lore.kernel.org/lkml/87fra90xv4.fsf@jogness.linutronix.de
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

Thanks for catching and fixing the problem:

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

Best Regards,
Petr