linux-kernel - Re: [RFC][PATCH 4/4] printk: enable printk offloading

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Message-ID: <20170322154327.GD4008@pathway.suse.cz>
Date:   Wed, 22 Mar 2017 16:43:27 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [RFC][PATCH 4/4] printk: enable printk offloading

On Mon 2017-03-06 21:45:54, Sergey Senozhatsky wrote:
> Initialize the kernel printing thread and enable printk()
> offloading.

The patch looks fine to me. But it might get more complicated
if we decide to have a global option to avoid the kthread.
Let's discuss this in the 3rd patch first.

Best Regards,
Petr

> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> ---
>  kernel/printk/printk.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 6e00073a7331..601a9ef6db89 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2779,6 +2779,25 @@ static int printk_kthread_func(void *data)
>  	return 0;
>  }
>  
> +/*
> + * Init printk kthread at late_initcall stage, after core/arch/device/etc.
> + * initialization.
> + */
> +static int __init init_printk_kthread(void)
> +{
> +	struct task_struct *thread;
> +
> +	thread = kthread_run(printk_kthread_func, NULL, "printk");
> +	if (IS_ERR(thread)) {
> +		pr_err("printk: unable to create printing thread\n");
> +		return PTR_ERR(thread);
> +	}
> +
> +	printk_kthread = thread;
> +	return 0;
> +}
> +late_initcall(init_printk_kthread);
> +
>  void wake_up_klogd(void)
>  {
>  	preempt_disable();
> -- 
> 2.12.0
>