linux-kernel - Re: [PATCH v5 2/3] fbcon: Call WARN_CONSOLE

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Message-ID: <20180711235956.GA4829@jagdpanzerIV>
Date:   Thu, 12 Jul 2018 08:59:56 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-fbdev@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/3] fbcon: Call WARN_CONSOLE_UNLOCKED() where
 applicable

Hi,

On (07/11/18 16:46), Thomas Zimmermann wrote:
> Am 28.06.2018 um 11:03 schrieb Hans de Goede:
> > Replace comments about places where the console lock should be held with
> > calls to WARN_CONSOLE_UNLOCKED() to assert that it is actually held.
> 
> Debugging fbcon sometimes requires to not take the console lock. This
> patch breaks the debugging workaround provided by
> 'fb.lockless_register_fb'. The dmesg is now filled with warnings about
> the missing lock.

Hmm. I once dealt with WARN_CONSOLE_UNLOCKED(), and back then, IIRC,
I really wanted to turn it into WARN_ONCE_CONSOLE_UNLOCKED(), which
would WARN_ON_ONCE() instead of WARN_ON(). It's just a bit too noisy
and verbose and a single backtrace was already enough.

	-ss