linux-kernel - Re: [PATCH update] firewire: fix "kobject

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Date:	Mon, 28 Jan 2008 17:30:47 -0500
From:	Jarod Wilson <jwilson@...hat.com>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	linux1394-devel@...ts.sourceforge.net,
	Kristian Høgsberg <krh@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH update] firewire: fix "kobject_add failed for fw* with -EEXIST"

On Sunday 27 January 2008 12:20:40 pm Stefan Richter wrote:
> There is a race between shutdown and creation of devices:  fw-core may
> attempt to add a device with the same name of an already existing
> device.  http://bugzilla.kernel.org/show_bug.cgi?id=9828
>
> Impact of the bug:  Happens rarely, forces the user to unplug and replug
> the new device to get it working.
>
> The fix moves deregistration of the minor number and device_unregister()
> into a common rw_sem protected section.
>
> We also move the ref count increment from fw_device_op_open into an
> rw_sem protected section with the lookup of the device, so that the
> device pointer can't become invalid between lookup and usage.
>
> Signed-off-by: Stefan Richter <stefanr@...6.in-berlin.de>

While I've got remaining issues with firewire mdraid, this does appear fix the 
problem of devices racing the grab the same fw* device node, and it seems 
obvious that should indeed be the case from the code changes.

Signed-off-by: Jarod Wilson <jwilson@...hat.com>

-- 
Jarod Wilson
jwilson@...hat.com
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