From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: linux-media@vger.kernel.org,
Mauro Carvalho Chehab <mchehab@infradead.org>,
Hans de Goede <hdegoede@redhat.com>,
Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
Pawel Osciak <pawel@osciak.com>,
Tomasz Stanislawski <t.stanislaws@samsung.com>,
Hans Verkuil <hans.verkuil@cisco.com>
Subject: Re: [RFCv2 PATCH 19/34] v4l2-dev.c: add debug sysfs entry.
Date: Wed, 27 Jun 2012 12:52:34 +0200 [thread overview]
Message-ID: <21286481.7Pjdm1koZj@avalon> (raw)
In-Reply-To: <201206271238.54332.hverkuil@xs4all.nl>
Hi Hans,
On Wednesday 27 June 2012 12:38:54 Hans Verkuil wrote:
> On Wed 27 June 2012 11:54:40 Laurent Pinchart wrote:
> > On Friday 22 June 2012 14:21:13 Hans Verkuil wrote:
> > > From: Hans Verkuil <hans.verkuil@cisco.com>
> > >
> > > Since this could theoretically change the debug value while in the
> > > middle of v4l2-ioctl.c, we make a copy of vfd->debug to ensure
> > > consistent debug behavior.
> >
> > In my review of RFCv1, I wrote that this could introduce a race condition:
> >
> > "You test the debug value several times in the __video_do_ioctl()
> > function. I haven't checked in details whether changing the value between
> > the two tests could for instance lead to a KERN_CONT print without a
> > previous non-KERN_CONT message. That won't crash the machine but it
> > should still be avoided."
> >
> > Have you verified whether that problem can occur ?
>
> Yes, this problem can occur. Which is why I've changed the code accordingly.
I've missed that. My bad, sorry.
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2012-06-27 10:52 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-22 12:20 [RFCv2 PATCH 00/34] Core and vb2 enhancements Hans Verkuil
2012-06-22 12:20 ` [RFCv2 PATCH 01/34] Regression fixes Hans Verkuil
2012-06-22 12:20 ` [RFCv2 PATCH 02/34] v4l2-ioctl.c: move a block of code down, no other changes Hans Verkuil
2012-06-22 12:20 ` [RFCv2 PATCH 03/34] v4l2-ioctl.c: introduce INFO_FL_CLEAR to replace switch Hans Verkuil
2012-06-22 12:20 ` [RFCv2 PATCH 04/34] v4l2-ioctl.c: v4l2-ioctl: add debug and callback/offset functionality Hans Verkuil
2012-06-22 12:20 ` [RFCv2 PATCH 05/34] v4l2-ioctl.c: remove an unnecessary #ifdef Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 06/34] v4l2-ioctl.c: use the new table for querycap and i/o ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 07/34] v4l2-ioctl.c: use the new table for priority ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 08/34] v4l2-ioctl.c: use the new table for format/framebuffer ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 09/34] v4l2-ioctl.c: use the new table for overlay/streamon/off ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 10/34] v4l2-ioctl.c: use the new table for std/tuner/modulator ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 11/34] v4l2-ioctl.c: use the new table for queuing/parm ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 12/34] v4l2-ioctl.c: use the new table for control ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 13/34] v4l2-ioctl.c: use the new table for selection ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 14/34] v4l2-ioctl.c: use the new table for compression ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 15/34] v4l2-ioctl.c: use the new table for debug ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 16/34] v4l2-ioctl.c: use the new table for preset/timings ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 17/34] v4l2-ioctl.c: use the new table for the remaining ioctls Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 18/34] v4l2-ioctl.c: finalize table conversion Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 19/34] v4l2-dev.c: add debug sysfs entry Hans Verkuil
2012-06-27 9:54 ` Laurent Pinchart
2012-06-27 10:38 ` Hans Verkuil
2012-06-27 10:52 ` Laurent Pinchart [this message]
2012-06-22 12:21 ` [RFCv2 PATCH 20/34] v4l2-ioctl: remove v4l_(i2c_)print_ioctl Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 21/34] ivtv: don't mess with vfd->debug Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 22/34] cx18: " Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 23/34] vb2-core: refactor reqbufs/create_bufs Hans Verkuil
2012-06-27 9:52 ` Laurent Pinchart
2012-06-27 10:37 ` Hans Verkuil
2012-06-27 10:49 ` Laurent Pinchart
2012-06-22 12:21 ` [RFCv2 PATCH 24/34] vb2-core: add support for count == 0 in create_bufs Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 25/34] Spec: document CREATE_BUFS behavior if count == 0 Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 26/34] v4l2-dev/ioctl.c: add vb2_queue support to video_device Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 27/34] videobuf2-core: add helper functions Hans Verkuil
2012-06-27 9:42 ` Laurent Pinchart
2012-06-27 10:31 ` Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 28/34] vivi: remove pointless g/s_std support Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 29/34] vivi: embed struct video_device instead of allocating it Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 30/34] vivi: use vb2 helper functions Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 31/34] vivi: add create_bufs/preparebuf support Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 32/34] v4l2-dev.c: also add debug support for the fops Hans Verkuil
2012-06-27 9:59 ` Laurent Pinchart
2012-06-27 10:44 ` Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 33/34] pwc: use the new vb2 helpers Hans Verkuil
2012-06-22 12:21 ` [RFCv2 PATCH 34/34] pwc: v4l2-compliance fixes Hans Verkuil
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