On Wed, Feb 17, 2016 at 10:02 AM, Avery Pennarun <apenwarr@xxxxxxxxx> wrote: > > On Tue, Feb 16, 2016 at 5:05 PM, Johannes Berg > <johannes@xxxxxxxxxxxxxxxx> wrote: > > On Tue, 2016-02-16 at 16:28 -0500, Avery Pennarun wrote: > >> Changing default_agg_timeout to zero (as it is on most non-ath9k > >> drivers) makes the problem pretty much go away. However, I think > >> it's because I'm just dodging the code path that triggers a race > >> condition. > > > > That does seem likely. Perhaps you could reproduce it while running > > mac80211 tracing? There should be a fair amount of information about > > aggregation and queue stops in there, though as you note queue stops > > aren't really happening, only aggregation related things. Perhaps the > > tracepoints for that aren't quite sufficient. > > So far that hasn't seemed to help, although maybe you can read traces > better than I can. The big problem is that the actual queue doesn't > seem to have stopped; it might be an ath9k bug. > > >> Notes: > >> > >> - I'm using exactly the same ath9k driver (currently 20150525, but > >> we've tried newer ones with no difference) on two totally different > >> platforms: a dual-core mindspeed c2k host CPU (ARMv7) with separate > >> ath9k, and a single-core QCA9531 (MIPS) with on-chip ath9k. > >> > >> - I've been unable to trigger the problem on the QCA9531, but I have > >> on MIPS. > > > > That's ... not what I would have expected, especially since the MIPS is > > single core. That makes the races stranger than expected. > > Oops, typo. The QCA9531 *is* MIPS. The one where it triggers is the > dual-core ARM. > > >> The aggregation code is... a little hairy. Does anyone have any > >> guesses where I might look for the race condition? Or better still, > >> a patch I can try? > > > > I'm not aware of any race conditions in the code right now :) > > Aw. That would have made it a lot easier! >From a quick glance of symptoms, i think the below patch is worth a try, even though i don't see you are doing any background scans for which this applies. https://patchwork.kernel.org/patch/8015321/ -- 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
