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

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Date:   Wed, 11 Jul 2018 23:09:12 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>,
        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, 12 Jul 2018 10:58:48 +0900
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> 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.

> 
> This makes me wonder - do we want to add more WARN_CONSOLE_UNLOCKED in the
> first place? :)

I would say yes.

> 
> Other than that, the patch looks OK to me I guess. I'm not super happy with
> more printk EXPORT_SYMBOL-s, frankly speaking, I'm not entirely in love with
> the "add a bool flag to suppress warn print outs which we added in the
> previous patch" direction, but if you guys want/need it...

I could add a comment explaining why it exists. Something like:

/*
 * Set this is you need to quiet WARN_CONSOLE_UNLOCKED() for debugging
 * purposes.
 */

> Probably I'm just dramatizing it, as usual ;)
> The removal of "#if 1" is definitely nice.

Yeah, that had to go regardless.

> 
> Let's hear from Petr.

Sure.

-- Steve