linux-kernel - Re: [PATCH] console: Replace #if 1 with a bool to ignore WARN_CONSOLE

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Date:   Thu, 12 Jul 2018 09:53:15 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] console: Replace #if 1 with a bool to ignore
 WARN_CONSOLE_UNLOCKED()

On Thu 2018-07-12 13:25:52, Sergey Senozhatsky wrote:
> On (07/11/18 23:09), Steven Rostedt wrote:
> > > On (07/11/18 15:17), Steven Rostedt wrote:
> > > > +bool ignore_console_lock_warning __read_mostly;
> > > > +EXPORT_SYMBOL(ignore_console_lock_warning);  
> > > 
> > > OK. So, to recap,
> > > We made is_console_locked() EXPORT_SYMBOL recently [it's still in linux-next],
> > > so people could use WARN_CONSOLE_UNLOCKED in more places; this made other
> > > people unhappy, so now we add another EXPORT_SYMBOL to the picture, which will
> > > disable those newly added WARN_CONSOLE_UNLOCKED and make other people happy
> > > again.
> > 
> > Note, it only made people that added a module parameter that disables
> > grabbing the console lock in the first place for debugging purposes
> > only. The added WARN_CONSOLE_UNLOCKED() are good. Nobody complaining
> > that they exist. They are complaining that it breaks one of their
> > debugging work flows, and need to disable it when they are doing so.
> 
> True, but at the same time nobody complained that we didn't have those
> extra WARN_CONSOLE_UNLOCKED()-s. Just saying. Over all I agree that there
> is probably some value in those extra WARN-s.

I agree that there is some value in the extra WARN's. Also it seems
that it is useful to disable them for debugging purposes. I do not
see a better solution. Therefore I am fine with this one.


> > I could add a comment explaining why it exists. Something like:
> > 
> > /*
> >  * Set this is you need to quiet WARN_CONSOLE_UNLOCKED() for debugging
> >  * purposes.
> >  */
> 
> s/is you/if you/

Yes, this extra comment would be appreciated.

If you send v2, please, break also the WARN definition to 80-chars's
per line ;-)


> Suggested-by: One-of-those-commiters@...KnowWhoYouAre.org ;)

AFAIK, the change was actually suggested by Steven. The inspiration
is described by the line:

Link:
http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de


Finally, IMHO, it would make sense to push this change together with
the fbcon/vt side.

Best Regards,
Petr