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From: Thierry Reding <thierry.reding@gmail.com>
To: Paulo Zanoni <przanoni@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] drm/sysfs: Do not drop device reference twice
Date: Wed, 30 Oct 2013 22:18:15 +0100	[thread overview]
Message-ID: <20131030211814.GC7686@mithrandir> (raw)
In-Reply-To: <CA+gsUGSjJmqu9Ph0znE5XJJOJdeh-UT3z2Cjm7sEMB4F+ZtAvg@mail.gmail.com>


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On Wed, Oct 30, 2013 at 02:05:02PM -0200, Paulo Zanoni wrote:
> 2013/10/30 Thierry Reding <thierry.reding@gmail.com>:
> > device_unregister() already drops its reference to the struct device, so
> > explicitly calling put_device() before device_unregister() can cause the
> > device to have been freed before it can be unregistered.
> >
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> 
> I started investigating this problem yesterday and reached the same
> conclusion. The connector path can be easily reproduced on i915.ko:
> get a machine that has an eDP panel, physically disconnect the panel,
> boot the machine, "modprobe i915" and watch the segfault.
> 
> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> 
> I didn't really bisect, but I believe this is probably a regression
> from "drm/sysfs: sort out minor and connector device object
> lifetimes".

Yes, I think that's the one that broke it.

Thierry

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WARNING: multiple messages have this Message-ID (diff)
From: Thierry Reding <thierry.reding@gmail.com>
To: Paulo Zanoni <przanoni@gmail.com>
Cc: David Airlie <airlied@linux.ie>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] drm/sysfs: Do not drop device reference twice
Date: Wed, 30 Oct 2013 22:18:15 +0100	[thread overview]
Message-ID: <20131030211814.GC7686@mithrandir> (raw)
In-Reply-To: <CA+gsUGSjJmqu9Ph0znE5XJJOJdeh-UT3z2Cjm7sEMB4F+ZtAvg@mail.gmail.com>

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On Wed, Oct 30, 2013 at 02:05:02PM -0200, Paulo Zanoni wrote:
> 2013/10/30 Thierry Reding <thierry.reding@gmail.com>:
> > device_unregister() already drops its reference to the struct device, so
> > explicitly calling put_device() before device_unregister() can cause the
> > device to have been freed before it can be unregistered.
> >
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> 
> I started investigating this problem yesterday and reached the same
> conclusion. The connector path can be easily reproduced on i915.ko:
> get a machine that has an eDP panel, physically disconnect the panel,
> boot the machine, "modprobe i915" and watch the segfault.
> 
> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> 
> I didn't really bisect, but I believe this is probably a regression
> from "drm/sysfs: sort out minor and connector device object
> lifetimes".

Yes, I think that's the one that broke it.

Thierry

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  reply	other threads:[~2013-10-30 21:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-30 10:59 [PATCH] drm/sysfs: Do not drop device reference twice Thierry Reding
2013-10-30 16:05 ` Paulo Zanoni
2013-10-30 16:05   ` Paulo Zanoni
2013-10-30 21:18   ` Thierry Reding [this message]
2013-10-30 21:18     ` Thierry Reding
2013-10-30 18:06 ` Ben Widawsky
2013-10-30 18:06   ` Ben Widawsky

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