On Thu, Feb 05, 2009 at 08:07:45AM -0800, Johannes Berg wrote:
> When disabling TX aggregation because it was rejected or from
> the timer (it was not accepted), there is a window where we
> first set the state to operation, unlock, and then undo the
> whole thing. Avoid that by splitting up the stop function.
> Also get rid of the pointless sta_info indirection in the timer.
>
> Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> ---
> net/mac80211/agg-tx.c | 95 +++++++++++++++++++++++++-------------------------
> 1 file changed, 48 insertions(+), 47 deletions(-)
>
> --- wireless-testing.orig/net/mac80211/agg-tx.c 2009-01-29 02:03:28.000000000 +0100
> +++ wireless-testing/net/mac80211/agg-tx.c 2009-01-29 02:03:30.000000000 +0100
> @@ -123,6 +123,34 @@ void ieee80211_send_bar(struct ieee80211
> ieee80211_tx_skb(sdata, skb, 0);
> }
>
> +static int __ieee80211_stop_tx_ba_session(struct ieee80211_local *local,
> + struct sta_info *sta, u16 tid,
> + enum ieee80211_back_parties initiator)
> +{
> + int ret;
> + u8 *state;
> +
> + state = &sta->ampdu_mlme.tid_state_tx[tid];
> +
> + if (local->hw.ampdu_queues)
> + ieee80211_stop_queue(&local->hw, sta->tid_to_tx_q[tid]);
> +
> + *state = HT_AGG_STATE_REQ_STOP_BA_MSK |
> + (initiator << HT_AGG_STATE_INITIATOR_SHIFT);
> +
> + ret = local->ops->ampdu_action(&local->hw, IEEE80211_AMPDU_TX_STOP,
> + &sta->sta, tid, NULL);
> +
> + /* HW shall not deny going back to legacy */
> + if (WARN_ON(ret)) {
> + *state = HT_AGG_STATE_OPERATIONAL;
> + if (local->hw.ampdu_queues)
> + ieee80211_wake_queue(&local->hw, sta->tid_to_tx_q[tid]);
> + }
> +
> + return ret;
> +}
> +
> /*
> * After sending add Block Ack request we activated a timer until
> * add Block Ack response will arrive from the recipient.
> @@ -135,23 +163,13 @@ static void sta_addba_resp_timer_expired
> * flow in sta_info_create gives the TID as data, while the timer_to_id
> * array gives the sta through container_of */
> u16 tid = *(u8 *)data;
> - struct sta_info *temp_sta = container_of((void *)data,
> + struct sta_info *sta = container_of((void *)data,
> struct sta_info, timer_to_tid[tid]);
> -
> - struct ieee80211_local *local = temp_sta->local;
> - struct ieee80211_hw *hw = &local->hw;
> - struct sta_info *sta;
> + struct ieee80211_local *local = sta->local;
> u8 *state;
>
> - rcu_read_lock();
> -
> - sta = sta_info_get(local, temp_sta->sta.addr);
> - if (!sta) {
> - rcu_read_unlock();
> - return;
> - }
> -
> state = &sta->ampdu_mlme.tid_state_tx[tid];
> +
> /* check if the TID waits for addBA response */
> spin_lock_bh(&sta->lock);
> if (!(*state & HT_ADDBA_REQUESTED_MSK)) {
> @@ -161,21 +179,15 @@ static void sta_addba_resp_timer_expired
> printk(KERN_DEBUG "timer expired on tid %d but we are not "
> "expecting addBA response there", tid);
> #endif
> - goto timer_expired_exit;
> + return;
> }
>
> #ifdef CONFIG_MAC80211_HT_DEBUG
> printk(KERN_DEBUG "addBA response timer expired on tid %d\n", tid);
> #endif
>
> - /* go through the state check in stop_BA_session */
> - *state = HT_AGG_STATE_OPERATIONAL;
> + __ieee80211_stop_tx_ba_session(local, sta, tid, WLAN_BACK_INITIATOR);
> spin_unlock_bh(&sta->lock);
> - ieee80211_stop_tx_ba_session(hw, temp_sta->sta.addr, tid,
> - WLAN_BACK_INITIATOR);
> -
> -timer_expired_exit:
> - rcu_read_unlock();
> }
Do we not need the sta under rcu lock on the sta_addba_resp_timer_expired()?
With this patch wouldn't we have a race between passing this to
__ieee80211_stop_tx_ba_session() and it being removed using sta_info_destroy()?
Luis
--
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
