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Date: Sat, 2 Apr 2016 01:39:17 +0900
From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.com>,
        Tejun Heo <tj@kernel.org>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        linux-kernel@vger.kernel.org, Byungchul Park <byungchul.park@lge.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Jan Kara <jack@suse.cz>
Subject: Re: [RFC][PATCH v9 1/2] printk: Make printk() completely async
Message-ID: <20160401163917.GC1212@swordfish>
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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