On Wednesday 09 July 2008, Johannes Berg wrote: > On Wed, 2008-07-09 at 16:00 +0200, Michael Buesch wrote: > > On Wednesday 09 July 2008 16:04:50 Ivo van Doorn wrote: > > > On Wednesday 09 July 2008, Michael Buesch wrote: > > > > On Wednesday 09 July 2008 15:11:45 Ivo van Doorn wrote: > > > > > Currently only beacons generated in AP mode have the software > > > > > sequence number inserted. This means IBSS and Mesh mode are broken > > > > > for all hardware that require software sequence numbers. > > > > > > > > Does software seq numbering even work at all? > > > > What about packets that get sent between the driver requested the > > > > beacon and the driver does actually queue it? > > > > > > For rt2x00 the beacon is requested and queued within interrupt context > > > > Well, another CPU could be in progress of walking down the mac80211 TX code > > and aquire a sequence number in the meantime before you requested the beacon. > > However that frame will be blocked by your driver locks, so the two seq > > numbers of the beacon and the other frame will be swapped, as the driver > > will queue the beacon first. If rt2x00 would use a global lock to block all TX and beacons, then yes. But rt2x00 uses per-queue locking. When a beacon is being updated rt2x00 will still allow regular frames to be queued. But we can't halt the TX queues for the beacon update either, because ieee80211_stop_queues() should only be called from within the TX path. > Indeed, I was wrong. > > I wonder if we should remove the hwseq support completely. It's much > easier for the driver to do this, especially since we pass a vif pointer > with driver-private data to all relevant functions and the driver could > keep the current sequence number in there. Or, just like hwseq would, > keep a global sequence number? I think that would be moving the same problem to the driver side, and I am not really a big fan of the idea to put all queue handling under 1 big lock instead of the per-queue locking which is currently the case. > How does that affect multi-bss support btw? Do we have to use sw seqno > for that? As far as rt2x00 is concerned, all hardware that supports multi-bss also support HW sequence counters. rt2400pci and rt2500pci are the only ones requiring SW sequence counters, and they can't do multi-bss. Ivo -- 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
