The addba timer function acquires the sta spinlock,
but at the same time we try to del_timer_sync() it
under the spinlock which can produce deadlocks.
To fix this, always del_timer_sync() the timer in
ieee80211_process_addba_resp() and add it again
after checking the conditions, if necessary.
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
Looks like I forgot to send this when I made it and then hid it in the
middle of my patch pile and forgot!
net/mac80211/agg-tx.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
--- wireless-testing.orig/net/mac80211/agg-tx.c 2009-10-27 09:06:13.000000000 +0100
+++ wireless-testing/net/mac80211/agg-tx.c 2009-10-29 08:32:15.000000000 +0100
@@ -666,26 +666,25 @@ void ieee80211_process_addba_resp(struct
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)) {
- spin_unlock_bh(&sta->lock);
- return;
- }
+ if (!(*state & HT_ADDBA_REQUESTED_MSK))
+ goto timer_still_needed;
if (mgmt->u.action.u.addba_resp.dialog_token !=
sta->ampdu_mlme.tid_tx[tid]->dialog_token) {
- spin_unlock_bh(&sta->lock);
#ifdef CONFIG_MAC80211_HT_DEBUG
printk(KERN_DEBUG "wrong addBA response token, tid %d\n", tid);
#endif /* CONFIG_MAC80211_HT_DEBUG */
- return;
+ goto timer_still_needed;
}
- del_timer_sync(&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 */
+
if (le16_to_cpu(mgmt->u.action.u.addba_resp.status)
== WLAN_STATUS_SUCCESS) {
u8 curstate = *state;
@@ -699,5 +698,11 @@ void ieee80211_process_addba_resp(struct
} else {
___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);
}
--
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