linux-kernel - Re: [PATCH v2 3/3] power: process: use explicit levels for printk continuations

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Message-ID: <f4631f7bf0e1fe7b018ea24cb89aede7829581d2.camel@perches.com>
Date:   Fri, 25 Nov 2022 11:53:49 -0800
From:   Joe Perches <joe@...ches.com>
To:     Thomas Weißschuh <linux@...ssschuh.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        linux-pm@...r.kernel.org, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andy Whitcroft <apw@...onical.com>
Cc:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Dwaipayan Ray <dwaipayanray1@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: Re: [PATCH v2 3/3] power: process: use explicit levels for printk
 continuations

On Fri, 2022-11-25 at 20:09 +0100, Thomas Weißschuh wrote:
> Many of the printk messages emitted during suspend and resume are
> emitted in fragments using pr_cont()/KERN_CONT.
> 
> As during suspend and resume a lot of operations are happing in the
> kernel the chances are high that the fragments are interspersed with
> unrelated messages.
> 
> In this case if no explicit level is specified for the fragments the
> standard level is applied, which by default is KERN_WARNING.
> 
> If the user is only observing KERN_WARNING and *not* KERN_INFO messages
> they will see incomplete message fragments.
> 
> By specifing the correct printk level also with the continuations this
> mismatch can be avoided.
> Also it reduces the amount of false-positive KERN_WARNING messages.
> 
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
>  kernel/power/process.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/power/process.c b/kernel/power/process.c
[]
> @@ -82,7 +82,7 @@ static int try_to_freeze_tasks(bool user_only)
>  	elapsed_msecs = ktime_to_ms(elapsed);
>  
>  	if (todo) {
> -		pr_cont("\n");
> +		pr_info_cont("\n");

I think this isn't needed because of the immediately following pr_err.

>  		pr_err("Freezing of tasks %s after %d.%03d seconds "
>  		       "(%d tasks refusing to freeze, wq_busy=%d):\n",
>  		       wakeup ? "aborted" : "failed",