linux-kernel - Re: [PATCH] firewire: fill_bus_reset

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Message-Id: <1213366898.25956.0.camel@gaara.bos.redhat.com>
Date:	Fri, 13 Jun 2008 10:21:38 -0400
From:	Kristian Høgsberg <krh@...hat.com>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	linux1394-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: fill_bus_reset_event needs lock protection

On Fri, 2008-06-06 at 22:11 +0200, Stefan Richter wrote:
> Callers of fill_bus_reset_event() have to take card->lock.  Otherwise
> access to node data may oops if node removal is in progress.
> 
> A lockless alternative would be
> 
> -	event->local_node_id = card->local_node->node_id;
> +	tmp = fw_node_get(card->local_node);
> +	event->local_node_id = tmp->node_id;
> +	fw_node_put(tmp);
> 
> and ditto with the other node pointers which fill_bus_reset_event()
> accesses.  But I went the locked route because one of the two callers
> already holds the lock.  As a bonus, we don't need the memory barrier
> anymore because device->generation and device->node_id are written in
> a card->lock protected section.

Looks good to me.

Signed-off-by: Kristian Høgsberg <krh@...hat.com>


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