From: Arnd Bergmann <arnd@arndb.de>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
Frederic Weisbecker <fweisbec@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
John Kacur <jkacur@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jan Blunck <jblunck@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Mauro Carvalho Chehab <mchehab@infradead.org>,
Greg KH <gregkh@suse.de>,
Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH 0/5] Pushdown bkl from v4l ioctls
Date: Thu, 29 Apr 2010 09:38:09 +0200 [thread overview]
Message-ID: <201004290938.09573.arnd@arndb.de> (raw)
In-Reply-To: <201004290910.43412.laurent.pinchart@ideasonboard.com>
On Thursday 29 April 2010 09:10:42 Laurent Pinchart wrote:
> On Thursday 29 April 2010 08:44:29 Hans Verkuil wrote:
> >
> > 3) Investigate what needs to be done to replace the bkl with a v4l2-dev.c
> > global mutex. Those drivers that call the bkl themselves should probably be
> > converted to do proper locking, but there are only about 14 drivers that do
> > this. The other 60 or so drivers should work fine if a v4l2-dev global lock
> > is used. At this point the bkl is effectively removed from the v4l
> > subsystem.
> >
> > 4) Work on the remaining 60 drivers to do proper locking and get rid of the
> > v4l2-dev global lock. This is probably less work than it sounds.
> >
> > Since your patch moves everything down to the driver level it will actually
> > make this work harder rather than easier. And it touches almost all drivers
> > as well.
>
> Every driver will need to be carefully checked to make sure the BKL can be
> replaced by a v4l2-dev global mutex. Why would it be more difficult to do so
> if the BKL is pushed down to the drivers ?
Note that you can completely skip the step of a v4l2-dev global mutex with
Frederic's patch. This is the only use of the BKL in the common v4l2
code as far as I can tell, so instead of introducing yet another global
lock, you can go straight to stage 4 and look at each driver separately,
possibly introducing a per driver lock.
Arnd
next prev parent reply other threads:[~2010-04-30 20:32 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-27 9:18 [PATCH 00/10] bkl: pushdowns from Arnd, and compile fixes John Kacur
2010-04-27 9:18 ` [PATCH 01/10] dvb: push down BKL into ioctl functions John Kacur
2010-04-27 9:18 ` [PATCH 02/10] scsi: " John Kacur
2010-04-27 9:18 ` [PATCH 03/10] bkl: Fix up compile problems in megaraid from bkl push-down John Kacur
2010-04-27 9:18 ` [PATCH 04/10] bkl: Fix missing inode tw_chrdev_ioctl due to bkl pushdown John Kacur
2010-04-27 9:18 ` [PATCH 05/10] bkl: Fix missing inode in twl_chrdev_ioctl resulting from " John Kacur
2010-04-27 9:18 ` [PATCH 06/10] isdn: push down BKL into ioctl functions John Kacur
2010-04-27 9:18 ` [PATCH 07/10] staging: " John Kacur
2010-04-27 9:18 ` [PATCH 08/10] v4l: always use unlocked_ioctl John Kacur
2010-04-27 9:18 ` [PATCH 09/10] drivers: push down BKL into various drivers John Kacur
2010-04-27 9:18 ` [PATCH 10/10] bkl: Fix-up compile problems as a result of the bkl-pushdown John Kacur
2010-04-27 11:17 ` Arnd Bergmann
2010-04-27 11:54 ` John Kacur
2010-04-27 13:03 ` Arnd Bergmann
2010-04-28 12:24 ` Mauro Carvalho Chehab
2010-04-28 12:37 ` Hans Verkuil
2010-04-28 12:37 ` Hans Verkuil
2010-04-28 13:02 ` Laurent Pinchart
2010-04-28 14:46 ` Mauro Carvalho Chehab
2010-04-28 14:55 ` Linus Torvalds
2010-04-28 21:52 ` Frederic Weisbecker
2010-04-29 3:42 ` [PATCH 0/5] Pushdown bkl from v4l ioctls Frederic Weisbecker
2010-04-29 6:44 ` Hans Verkuil
2010-04-29 7:10 ` Laurent Pinchart
2010-04-29 7:38 ` Arnd Bergmann [this message]
2010-05-01 9:55 ` Hans Verkuil
2010-05-01 10:47 ` Arnd Bergmann
2010-05-01 14:58 ` Frederic Weisbecker
2010-05-01 11:11 ` Alan Cox
2010-04-29 3:42 ` [PATCH 1/5] v4l: Pushdown bkl into video_ioctl2 Frederic Weisbecker
2010-04-29 3:42 ` [PATCH 2/5] v4l: Use video_ioctl2_unlocked from drivers that don't want the bkl Frederic Weisbecker
2010-04-29 3:42 ` [PATCH 3/5] v4l: Change users of video_ioctl2 to use unlocked_ioctl Frederic Weisbecker
2010-04-29 3:42 ` [PATCH 4/5] v4l: Pushdown bkl to drivers that implement their own ioctl Frederic Weisbecker
2010-04-29 3:42 ` [PATCH 5/5] v4l: Remove struct v4l2_file_operations::ioctl Frederic Weisbecker
2010-04-27 11:31 ` [PATCH 00/10] bkl: pushdowns from Arnd, and compile fixes Arnd Bergmann
2010-04-27 12:19 ` John Kacur
2010-04-27 12:41 ` Frederic Weisbecker
2010-04-27 14:24 ` [PATCH 0/6] BKL pushdown into ioctl, continued Arnd Bergmann
2010-04-27 14:24 ` [PATCH 1/7] logfs: push down BKL into ioctl function Arnd Bergmann
2010-04-27 14:32 ` Arnd Bergmann
2010-04-27 14:58 ` Jörn Engel
2010-04-27 15:05 ` Arnd Bergmann
2010-04-27 15:09 ` Jörn Engel
2010-04-27 15:27 ` John Kacur
2010-04-27 15:32 ` Jörn Engel
2010-04-27 15:38 ` Arnd Bergmann
2010-04-27 20:12 ` Frederic Weisbecker
2010-04-27 20:30 ` [PATCH] logfs: kill BKL Arnd Bergmann
2010-05-19 12:51 ` Frederic Weisbecker
2010-04-27 15:36 ` [PATCH 1/7] logfs: push down BKL into ioctl function Linus Torvalds
2010-04-27 16:29 ` John Kacur
2010-04-27 19:59 ` Frederic Weisbecker
2010-04-27 14:24 ` [PATCH 2/7] hfsplus: " Arnd Bergmann
2010-04-27 14:24 ` [PATCH 3/7] cris: push down BKL into some device drivers Arnd Bergmann
2010-04-27 17:22 ` Frederic Weisbecker
2010-04-30 7:53 ` Jesper Nilsson
2010-05-17 2:51 ` Frederic Weisbecker
2010-04-27 14:24 ` [PATCH 4/7] sn_hwperf: kill BKL usage Arnd Bergmann
2010-04-27 14:24 ` [PATCH 5/7] um/mmapper: remove " Arnd Bergmann
2010-04-27 14:24 ` [PATCH 6/7] coda/psdev: remove BKL from ioctl function Arnd Bergmann
2010-04-27 14:24 ` [PATCH 7/7] smbfs: push down BKL into " Arnd Bergmann
2010-04-27 12:40 ` [PATCH 00/10] bkl: pushdowns from Arnd, and compile fixes Frederic Weisbecker
2010-04-27 12:51 ` Geert Uytterhoeven
2010-04-28 21:18 ` Frederic Weisbecker
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