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From: Lukas Wunner <lukas@wunner.de>
To: Wilfried Klaebe <linux-kernel@lebenslange-mailadresse.de>
Cc: platform-driver-x86@vger.kernel.org,
	Darren Hart <dvhart@infradead.org>,
	Andy Shevchenko <andy@infradead.org>,
	Petri Hodju <petrihodju@yahoo.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Bruno Premont <bonbons@linux-vserver.org>,
	Andy Ritger <aritger@nvidia.com>,
	Ronald Tschalaer <ronald@innovation.ch>
Subject: Re: [PATCH] Revert "apple-gmux: lock iGP IO to protect from vgaarb changes"
Date: Thu, 25 Jan 2018 21:25:30 +0100	[thread overview]
Message-ID: <20180125202530.GA7175@wunner.de> (raw)
In-Reply-To: <20180125201048.x3tr3xpovo5tzduz@chaos.in-kiel.de>

On Thu, Jan 25, 2018 at 09:10:48PM +0100, Wilfried Klaebe wrote:
> On Wed, Jan 24, 2018 at 07:35:45PM +0100, Lukas Wunner wrote:
> > * Wilfried Klaebe reports a deadlock when launching Xorg because it
> >   opens /dev/vga_arbiter and calls vga_get(), but apple-gmux is holding
> >   a lock on I/O space indefinitely.  It looks like apple-gmux' current
> >   behavior is an abuse of the vgaarb API as locks are not meant to be
> >   held for longer periods:
> >   https://bugzilla.kernel.org/show_bug.cgi?id=88861#c11
> >   https://bugzilla.kernel.org/attachment.cgi?id=217541
[...]
> I see warnings about possible circular locking regarding vgasr_mutex,
> but haven't had a deadlock yet. I'd be happy to provide more information
> as timely as job and family allow.

Could you attach dmesg output with that lockdep splat to the
above-quoted bugzilla entry?

Thanks,

Lukas

  reply	other threads:[~2018-01-25 20:25 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-24 18:35 [PATCH] Revert "apple-gmux: lock iGP IO to protect from vgaarb changes" Lukas Wunner
2018-01-25 20:10 ` Wilfried Klaebe
2018-01-25 20:25   ` Lukas Wunner [this message]
2018-01-26 18:53     ` Wilfried Klaebe
2018-01-25 22:38 ` Darren Hart
2018-01-26  0:57   ` Lukas Wunner
2018-01-31 18:39   ` Darren Hart
2018-01-31 19:44     ` Lukas Wunner
2018-02-01  1:31       ` Andy Ritger

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