On Fri, 2012-11-02 at 11:49 +0100, Karl Beldan wrote: > > The patches also add flow control to stop incoming tx packets when the > > DMA ring is full. In practice I found that we will sometimes receive a > > single frame from mac80211 after stopping the queues, so some headroom > > is reserved when stopping the queues. I also reduced the number of tx > > descriptors per ring to 64 and fixed a bug that prevented having > > differing non-zero numbers of tx and rx descriptors for a given ring. > > > It is strange that you would get one frame after stopping the queues. > Apart from the iface up/down code which I did not look at, it seems the tx > codepaths for queues stop/wake are all properly protected by spin_lock_bhs. > You mention a possible race in your code comments .. are you referring to > mac80211 or the driver itself ? It's generally a race between mac80211 and the driver, if the driver uses ieee80211_stop_queue() outside the TX path, the TX path can be handing it a packet at the exact same time, and therefore there can be one packet (on each queue!) that goes to the driver during the call to stop_queue(). 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
