From: Johannes Berg <johannes.berg@xxxxxxxxx> "mac80211: fix skb buffering issue" still left a race between enabling the hardware queues and the virtual interface queues. In hindsight it's totally obvious that enabling the netdev queues for a hardware queue when the hardware queue is enabled is wrong, because it could well possible that we can fill the hw queue with packets we already have pending. Thus, we must only enable the netdev queues once all the pending packets have been processed and sent off to the device. In testing, I haven't been able to trigger this race condition, but it's clearly there, possibly only when aggregation is being enabled. Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Cc: stable@xxxxxxxxxx --- net/mac80211/tx.c | 6 ++++++ net/mac80211/util.c | 12 ++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) --- wireless-testing.orig/net/mac80211/tx.c 2010-03-19 21:28:59.000000000 -0700 +++ wireless-testing/net/mac80211/tx.c 2010-03-19 21:29:13.000000000 -0700 @@ -1991,6 +1991,7 @@ static bool ieee80211_tx_pending_skb(str void ieee80211_tx_pending(unsigned long data) { struct ieee80211_local *local = (struct ieee80211_local *)data; + struct ieee80211_sub_if_data *sdata; unsigned long flags; int i; bool txok; @@ -2029,6 +2030,11 @@ void ieee80211_tx_pending(unsigned long if (!txok) break; } + + if (skb_queue_empty(&local->pending[i])) + list_for_each_entry_rcu(sdata, &local->interfaces, list) + netif_tx_wake_queue( + netdev_get_tx_queue(sdata->dev, i)); } spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags); --- wireless-testing.orig/net/mac80211/util.c 2010-03-19 21:28:59.000000000 -0700 +++ wireless-testing/net/mac80211/util.c 2010-03-22 13:37:34.000000000 -0700 @@ -279,13 +279,13 @@ static void __ieee80211_wake_queue(struc /* someone still has this queue stopped */ return; - if (!skb_queue_empty(&local->pending[queue])) + if (skb_queue_empty(&local->pending[queue])) { + rcu_read_lock(); + list_for_each_entry_rcu(sdata, &local->interfaces, list) + netif_tx_wake_queue(netdev_get_tx_queue(sdata->dev, queue)); + rcu_read_unlock(); + } else tasklet_schedule(&local->tx_pending_tasklet); - - rcu_read_lock(); - list_for_each_entry_rcu(sdata, &local->interfaces, list) - netif_tx_wake_queue(netdev_get_tx_queue(sdata->dev, queue)); - rcu_read_unlock(); } void ieee80211_wake_queue_by_reason(struct ieee80211_hw *hw, int queue, -- 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