mac80211: detect driver tx bugs

When a driver rejects a frame in it's ->tx() callback, it must also
stop queues, otherwise mac80211 can go into a loop here. Detect this
situation and abort the loop after five retries, warning about the
driver bug.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 1 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 28d8bd53bd3a..c80d5899f279 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1132,7 +1132,7 @@ static int ieee80211_tx(struct net_device *dev, struct sk_buff *skb,
         ieee80211_tx_handler *handler;
         struct ieee80211_tx_data tx;
         ieee80211_tx_result res = TX_DROP, res_prepare;
-        int ret, i;
+        int ret, i, retries = 0;
 
         WARN_ON(__ieee80211_queue_pending(local, control->queue));
 
@@ -1216,6 +1216,13 @@ retry:
                 if (!__ieee80211_queue_stopped(local, control->queue)) {
                         clear_bit(IEEE80211_LINK_STATE_PENDING,
                                   &local->state[control->queue]);
+                        retries++;
+                        /*
+                         * Driver bug, it's rejecting packets but
+                         * not stopping queues.
+                         */
+                        if (WARN_ON_ONCE(retries > 5))
+                                goto drop;
                         goto retry;
                 }
                 memcpy(&store->control, control,