From: Oliver Neukum <oliver@neukum.org>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Greg KH <greg@kroah.com>,
Mauro Carvalho Chehab <mchehab@infradead.org>,
Sarah Sharp <sarah.a.sharp@linux.intel.com>,
linux-usb@vger.kernel.org, linux-media@vger.kernel.org,
linux-kernel@vger.kernel.org, libusb-devel@lists.sourceforge.net,
Alexander Graf <agraf@suse.de>, Gerd Hoffmann <kraxel@redhat.com>,
hector@marcansoft.com, Jan Kiszka <jan.kiszka@siemens.com>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
pbonzini@redhat.com, Anthony Liguori <aliguori@us.ibm.com>,
Jes Sorensen <Jes.Sorensen@redhat.com>,
Alan Stern <stern@rowland.harvard.edu>,
Felipe Balbi <balbi@ti.com>, Clemens Ladisch <clemens@ladisch.de>,
Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.de>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Theodore Kilgore <kilgota@banach.math.auburn.edu>,
Adam Baker <linux@baker-net.org.uk>
Subject: Re: USB mini-summit at LinuxCon Vancouveroliver
Date: Fri, 5 Aug 2011 09:59:00 +0200 [thread overview]
Message-ID: <201108050959.00873.oliver@neukum.org> (raw)
In-Reply-To: <4E3B9FB4.30709@redhat.com>
Am Freitag, 5. August 2011, 09:45:56 schrieb Hans de Goede:
> This is the issue on which I feel a bit stonewalled. Simple putting your
> fingers in your ears and singing la la la do it in userspace is not going
> to cut it here. There is no way to do this race free in userspace, unless
> all possible callers of mount get modified. Moreover 99% of the necessary
> accounting for this is already done in the kernel. We already have the notion
> of a block device being in use. We simply need to add some code to pass
> this notion to the usb mass storage driver, and add a new try_disconnect
> callback for usb drivers. I'm not saying this is going to be completely
> straight forward, but it ain't rocket science either. And it so very
> obviously is the right thing to do, that I'm getting very tired of
> the do it in userspace song I keep hearing.
Doing a try_disconnect() would also solve the dual camera issue.
But it doesn't really interfere with the user space vs. kernel space
issue. You simply have to expand the ioctl interface to have
an ioctl that triggers this API call in the kernel.
A V4L2 device would return an error if its device node is opened,
otherwise disconnect.
Regards
Oliver
next prev parent reply other threads:[~2011-08-05 7:56 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-10 0:21 USB mini-summit at LinuxCon Vancouver Sarah Sharp
2011-06-10 3:18 ` Greg KH
2011-06-10 6:59 ` Gerd Hoffmann
2011-06-10 19:48 ` Sarah Sharp
2011-06-10 20:50 ` Greg KH
2011-06-13 10:44 ` Alexander Graf
2011-06-13 10:44 ` Alexander Graf
2011-06-13 16:29 ` Greg KH
2011-06-13 16:29 ` Greg KH
2011-06-13 17:11 ` Alexander Graf
2011-06-13 17:11 ` Alexander Graf
2011-06-10 7:19 ` Hans de Goede
2011-06-10 7:55 ` Improving kernel -> userspace (usbfs) usb device hand off Hans de Goede
2011-06-10 8:22 ` Felipe Balbi
2011-06-10 8:36 ` Hans de Goede
2011-06-10 8:42 ` Felipe Balbi
2011-06-10 12:19 ` Hans de Goede
2011-06-10 12:28 ` Felipe Balbi
2011-06-10 14:48 ` Alan Stern
2011-06-10 15:07 ` Mauro Carvalho Chehab
2011-06-10 15:21 ` Alan Stern
2011-06-11 9:15 ` Hans de Goede
2011-06-11 16:19 ` Theodore Kilgore
2011-06-12 11:43 ` Hans de Goede
2011-06-12 21:20 ` Theodore Kilgore
2011-06-13 2:03 ` Xiaofan Chen
2011-06-13 2:27 ` [Libusb-devel] " Michael Bender
2011-06-11 16:57 ` Alan Stern
2011-06-10 18:16 ` Theodore Kilgore
2011-06-10 18:34 ` Felipe Balbi
2011-06-10 21:18 ` Alan Stern
2011-06-10 21:46 ` Felipe Balbi
2011-06-10 22:46 ` Theodore Kilgore
2011-06-10 22:43 ` Theodore Kilgore
2011-06-11 1:30 ` Xiaofan Chen
2011-06-11 4:17 ` Theodore Kilgore
2011-06-13 9:05 ` Felipe Balbi
2011-06-13 13:06 ` Mauro Carvalho Chehab
2011-06-13 13:12 ` Felipe Balbi
2011-08-04 22:21 ` USB mini-summit at LinuxCon Vancouver Mauro Carvalho Chehab
2011-08-04 22:56 ` Greg KH
[not found] ` <CAA6KcBBZv7bvVxvEWOYL83igpNZHyzh=bcGxh6Dr5aKsvJK5Cg@mail.gmail.com>
2011-08-05 0:33 ` Mauro Carvalho Chehab
2011-08-05 2:56 ` Theodore Kilgore
2011-08-05 6:57 ` Oliver Neukum
2011-08-05 17:38 ` Theodore Kilgore
2011-08-05 7:45 ` Hans de Goede
2011-08-05 7:59 ` Oliver Neukum [this message]
2011-08-05 8:18 ` USB mini-summit at LinuxCon Vancouveroliver Hans de Goede
2011-08-05 13:07 ` USB mini-summit at LinuxCon Vancouver Mauro Carvalho Chehab
2011-08-08 17:58 ` Sarah Sharp
2011-08-08 18:23 ` Theodore Kilgore
2011-08-08 18:32 ` Sarah Sharp
2011-08-08 19:37 ` Mauro Carvalho Chehab
2011-08-09 7:52 ` Hans de Goede
2011-08-09 14:19 ` Alan Stern
2011-08-09 15:03 ` Marko Ristola
2011-08-09 19:57 ` Hans de Goede
2011-08-09 20:31 ` Adam Baker
2011-08-09 20:57 ` Hans de Goede
2011-08-10 2:05 ` Xiaofan Chen
2011-08-10 23:04 ` Adam Baker
2011-08-11 8:14 ` Hans de Goede
2011-08-09 23:05 ` Theodore Kilgore
2011-08-10 14:19 ` Alan Stern
2011-08-10 15:03 ` Theodore Kilgore
2011-08-10 16:09 ` Alan Stern
2011-08-10 18:33 ` Theodore Kilgore
2011-08-10 19:39 ` Hans Verkuil
2011-08-10 19:43 ` Greg KH
2011-08-10 20:34 ` Theodore Kilgore
2011-08-10 20:14 ` Mauro Carvalho Chehab
2011-08-10 20:39 ` Theodore Kilgore
2011-08-11 8:57 ` Jean-Francois Moine
2011-08-11 11:19 ` Mauro Carvalho Chehab
2011-08-11 8:14 ` Hans de Goede
2011-08-11 14:56 ` Alan Stern
2011-08-11 15:13 ` Mauro Carvalho Chehab
2011-08-11 15:25 ` Alan Cox
2011-08-11 15:49 ` Alan Stern
2011-08-11 20:01 ` Theodore Kilgore
2011-08-11 20:32 ` Mauro Carvalho Chehab
2011-08-11 23:13 ` Theodore Kilgore
2011-08-12 7:16 ` Hans de Goede
2011-08-12 10:11 ` Alan Cox
2011-08-12 1:07 ` Alan Stern
2011-08-12 2:38 ` Theodore Kilgore
2011-08-11 15:44 ` Alan Stern
2011-08-12 7:26 ` Hans de Goede
2011-08-12 15:36 ` Alan Stern
2011-08-09 17:10 ` Sarah Sharp
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