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

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Message-ID: <ad4e4785-c6f8-4ae1-a281-ff9dc5720db2@t-8ch.de>
Date:   Fri, 25 Nov 2022 21:41:55 +0100
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Joe Perches <joe@...ches.com>
Cc:     "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>,
        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 2022-11-25 11:53-0800, Joe Perches wrote:
> 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.

The pr_cont() itself or the conversion to pr_info_cont() is not needed?

Personally I would prefer to keep the patch as is.

If only the conversion is not needed for consistency with the rest of the file.
If the pr_cont() in general is not needed it should be changed in a dedicated
patch (by somebody who knows this code better).

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