Is possible that we stop queue and then do not wake up it again,
especially when packets are transmitted fast. That can be easily
reproduced with modified tx queue entry_num to some small value e.g. 16.
If mac80211 already hold local->queue_stop_reason_lock, then we can wait
on that lock in both rt2x00queue_pause_queue() and
rt2x00queue_unpause_queue(). After drooping ->queue_stop_reason_lock
is possible that __ieee80211_wake_queue() will be performed before
__ieee80211_stop_queue(), hence we stop queue and newer wake up it
again.
To prevent stalls serialize pause/unpause by queue->tx_lock.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
---
drivers/net/wireless/rt2x00/rt2x00dev.c | 10 ++++++++--
drivers/net/wireless/rt2x00/rt2x00mac.c | 10 +++++++++-
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 49a51b4..6c64658 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -430,10 +430,16 @@ void rt2x00lib_txdone(struct queue_entry *entry,
/*
* If the data queue was below the threshold before the txdone
* handler we must make sure the packet queue in the mac80211 stack
- * is reenabled when the txdone handler has finished.
+ * is reenabled when the txdone handler has finished. This has to be
+ * serialized with rt2x00mac_tx, otherwise we can wake up mac80211
+ * queue before it was stopped if someone else hold mac80211 internal
+ * local->queue_stop_reason_lock .
*/
- if (!rt2x00queue_threshold(entry->queue))
+ if (!rt2x00queue_threshold(entry->queue)) {
+ spin_lock_irq(&entry->queue->tx_lock);
rt2x00queue_unpause_queue(entry->queue);
+ spin_unlock_irq(&entry->queue->tx_lock);
+ }
}
EXPORT_SYMBOL_GPL(rt2x00lib_txdone);
diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c
index ede3c58..2880512 100644
--- a/drivers/net/wireless/rt2x00/rt2x00mac.c
+++ b/drivers/net/wireless/rt2x00/rt2x00mac.c
@@ -152,13 +152,21 @@ void rt2x00mac_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
if (unlikely(rt2x00queue_write_tx_frame(queue, skb, false)))
goto exit_fail;
- if (rt2x00queue_threshold(queue))
+ /*
+ * Pausing queue has to be serialized with rt2x00lib_txdone .
+ */
+ if (rt2x00queue_threshold(queue)) {
+ spin_lock(&queue->tx_lock);
rt2x00queue_pause_queue(queue);
+ spin_unlock(&queue->tx_lock);
+ }
return;
exit_fail:
+ spin_lock(&queue->tx_lock);
rt2x00queue_pause_queue(queue);
+ spin_unlock(&queue->tx_lock);
exit_free_skb:
ieee80211_free_txskb(hw, skb);
}
--
1.7.1
--
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
