Re: [PATCH] wext: fix get_wireless_stats locking

["John W. Linville" <linville@tuxdriver.com>]

On Sun, May 10, 2009 at 01:00:17PM +0200, Johannes Berg wrote:
> Currently, get_wireless_stats is racy by _design_. This is
> because it returns a buffer, which needs to be statically
> allocated since it cannot be freed if it was allocated
> dynamically. Also, SIOCGIWSTATS and /proc/net/wireless use
> no common lock, and /proc/net/wireless accesses are not
> synchronised against each other. This is a design flaw in
> get_wireless_stats since the beginning.
> 
> This patch fixes it by wrapping /proc/net/wireless accesses
> with the RTNL so they are protected against each other and
> SIOCGIWSTATS. The more correct method of fixing this would
> be to pass in the buffer instead of returning it and have
> the caller take care of synchronisation of the buffer, but
> even then most drivers probably assume that their callback
> is protected by the RTNL like all other wext callbacks.
> 
> Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

Is it acceptable to hold rtnl between ->open and ->release?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.