mac80211: fix addba timer (again...)

commit 2171abc58644e09dbba546d91366b12743115396
  Author: Johannes Berg <johannes@sipsolutions.net>
  Date:   Thu Oct 29 08:34:00 2009 +0100

      mac80211: fix addba timer

left a problem in there, even if the timer was
never started it could be deleted and then added.

Linus pointed out that del_timer_sync() isn't
actually needed if we make the timer able to
deal with no longer being needed when it gets
queued _while_ we're in the locked section that
also deletes it. For that the timer function only
needs to check the HT_ADDBA_RECEIVED_MSK bit as
well as the HT_ADDBA_REQUESTED_MSK bit, only if
the former is clear should it do anything.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 8 insertions, 10 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index b09948ceec4a..206fd82f0c76 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -173,12 +173,14 @@ static void sta_addba_resp_timer_expired(unsigned long data)
 
         /* check if the TID waits for addBA response */
         spin_lock_bh(&sta->lock);
-        if (!(*state & HT_ADDBA_REQUESTED_MSK)) {
+        if ((*state & (HT_ADDBA_REQUESTED_MSK | HT_ADDBA_RECEIVED_MSK)) !=
+                                                HT_ADDBA_REQUESTED_MSK) {
                 spin_unlock_bh(&sta->lock);
                 *state = HT_AGG_STATE_IDLE;
 #ifdef CONFIG_MAC80211_HT_DEBUG
                 printk(KERN_DEBUG "timer expired on tid %d but we are not "
-                                "expecting addBA response there", tid);
+                                "(or no longer) expecting addBA response there",
+                        tid);
 #endif
                 return;
         }
@@ -666,21 +668,21 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
 
         state = &sta->ampdu_mlme.tid_state_tx[tid];
 
-        del_timer_sync(&sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer);
-
         spin_lock_bh(&sta->lock);
 
         if (!(*state & HT_ADDBA_REQUESTED_MSK))
-                goto timer_still_needed;
+                goto out;
 
         if (mgmt->u.action.u.addba_resp.dialog_token !=
                 sta->ampdu_mlme.tid_tx[tid]->dialog_token) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
                 printk(KERN_DEBUG "wrong addBA response token, tid %d\n", tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
-                goto timer_still_needed;
+                goto out;
         }
 
+        del_timer(&sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer);
+
 #ifdef CONFIG_MAC80211_HT_DEBUG
         printk(KERN_DEBUG "switched off addBA timer for tid %d \n", tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
@@ -699,10 +701,6 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
                 ___ieee80211_stop_tx_ba_session(sta, tid, WLAN_BACK_INITIATOR);
         }
 
-        goto out;
-
- timer_still_needed:
-        add_timer(&sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer);
  out:
         spin_unlock_bh(&sta->lock);
 }