linux-kernel - Re: [RFC][PATCH v9 1/2] printk: Make printk() completely async

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] [day] [month] [year] [list]

Date:	Sat, 2 Apr 2016 01:39:17 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Petr Mladek <pmladek@...e.com>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kara <jack@...e.com>, Tejun Heo <tj@...nel.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	linux-kernel@...r.kernel.org,
	Byungchul Park <byungchul.park@....com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Jan Kara <jack@...e.cz>
Subject: Re: [RFC][PATCH v9 1/2] printk: Make printk() completely async

On (04/01/16 17:00), Petr Mladek wrote:
> You need to move this assigment right above the console_lock()/console_unlock()
> calls. Otherwise, there is a race:
> 
> CPU0:				CPU1
> 
> printk_kthread_func()
> 
>   console_unlock()
> 
> 				printk()
> 
> 				printk_kthread_need_flush_console = true;
> 				wake_up_process(printk_kthread);
> 
>   printk_kthread_need_flush_console = false;
> 
>   set_current_state(TASK_INTERRUPTIBLE);
>   if (!printk_kthread_need_flush_console)
>     schedule();

thanks. yeah, this can add latency to some messages.

	-ss