linux-kernel - Re: [PATCH 4/4 update] firewire: fw-core: react on bus resets while the config ROM is being fetched

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Message-Id: <200801251216.35291.jwilson@redhat.com>
Date:	Fri, 25 Jan 2008 12:16:35 -0500
From:	Jarod Wilson <jwilson@...hat.com>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	Kristian Høgsberg <krh@...hat.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	linux1394-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4 update] firewire: fw-core: react on bus resets while the config ROM is being fetched

On Friday 25 January 2008 11:53:49 am Stefan Richter wrote:
> read_rom() obtained a fresh new fw_device.generation for each read
> transaction.  Hence it was able to continue reading in the middle of the
> ROM even if a bus reset happened.  However the device may have modified
> the ROM during the reset.  We would end up with a corrupt fetched ROM
> image then.
>
> Although all of this is quite unlikely, it is not impossible.
> Therefore we now restart reading the ROM if the bus generation changed.
>
> Note, the memory barrier in read_rom() is still necessary according to
> tests by Jarod Wilson, despite of the ->generation access being moved up
> in the call chain.
>
> Signed-off-by: Stefan Richter <stefanr@...6.in-berlin.de>
> ---
>
> First posted on 2007-11-01.  Update:  Barrier stays.

This is essentially what I've been beating on locally, and I've yet to hit 
another config rom read failure with it.

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


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