From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: linux-media@vger.kernel.org
Subject: Re: cx231xx: possible circular locking dependency detected on 3.2
Date: Sat, 7 Jan 2012 15:29:08 +0100 [thread overview]
Message-ID: <20120107152908.3b8a78d8@skate> (raw)
In-Reply-To: <20120106224231.455a9896@skate>
Le Fri, 6 Jan 2012 22:42:31 +0100,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a écrit :
> Hello,
>
> I'm running the Hauppauge USB-Live 2 device on an ARM OMAP3 platform.
> After loading the cx231xx driver and launching v4l2grab, I immediately
> get:
>
> [ 407.087158] cx231xx #0: setPowerMode::mode = 48, No Change req.
> [ 407.145477]
> [ 407.147064] ======================================================
> [ 407.153533] [ INFO: possible circular locking dependency detected ]
> [ 407.160095] 3.2.0-00007-gb928298 #18
> [ 407.163848] -------------------------------------------------------
One code path is (mmap_sem taken before, video_device lock taken
afterwards) :
-> sys_mmap_pgoff()
grabs current->mm->mmap_sem at
http://lxr.free-electrons.com/source/mm/mmap.c#L1111
-> do_mmap_pgoff()
-> mmap_region()
-> v4l2_mmap()
grabs struct video_device->lock at
http://lxr.free-electrons.com/source/drivers/media/video/v4l2-dev.c#L396
The other code path is (video_device taken first, mmap_sem taken
afterwards) :
-> v4l2_ioctl()
grabs video_device->lock at
http://lxr.free-electrons.com/source/drivers/media/video/v4l2-dev.c#L327
-> video_ioctl2()
-> video_usercopy()
-> __video_do_ioctl()
-> videobuf_qbuf()
grabs current->mm->mmap_sem at
http://lxr.free-electrons.com/source/drivers/media/video/videobuf-core.c#L537
Regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
prev parent reply other threads:[~2012-01-07 14:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-06 21:42 cx231xx: possible circular locking dependency detected on 3.2 Thomas Petazzoni
2012-01-07 14:29 ` Thomas Petazzoni [this message]
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