On Thu, 2015-03-05 at 16:52 +0100, Sven Eckelmann wrote: > On Thursday 05 March 2015 16:37:12 Johannes Berg wrote: > > From: Johannes Berg <johannes.berg@xxxxxxxxx> > > > > Both minstrel (reported by Sven Eckelmann) and the iwlwifi rate > > control aren't properly taking concurrency into account. It's > > likely that the same is true for other rate control algorithms. > > > > In the case of minstrel this manifests itself in crashes when an > > update and other data access are run concurrently, for example > > when the stations change bandwidth or similar. In iwlwifi, this > > can cause firmware crashes. > > > > Since fixing all rate control algorithms will be very difficult, > > just provide locking for invocations. This protects the internal > > data structures the algorithms maintain. > > > > I've manipulated hostapd to test this, by having it change its > > advertised bandwidth roughly ever 150ms. At the same time, I'm > > running a flood ping between the client and the AP, which causes > > this race of update vs. get_rate/status to easily happen on the > > client. With this change, the system survives this test. > > > > Reported-by: Sven Eckelmann <sven@xxxxxxxxxxxxx> > > Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> > > Thanks a lot for the patch. This is mostly what I had in mind when asking for > the correct lock. > > I will ask if it is possible to test this patch in an affected network. Actually, don't. This patch has a bug that causes crashes. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
