[patch 04/47] mac80211: detect driver tx bugs

[Greg KH]

2.6.25-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>

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.

This patch was added to mainline as
commit ef3a62d272f033989e83eb1f26505f93f93e3e69.

Thanks to Larry Finger <Larry.Finger@xxxxxxxxxxxx> for doing the -stable
port.

Cc: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>

---
 net/mac80211/tx.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1090,7 +1090,7 @@ static int ieee80211_tx(struct net_devic
 	ieee80211_tx_handler *handler;
 	struct ieee80211_txrx_data tx;
 	ieee80211_txrx_result res = TXRX_DROP, res_prepare;
-	int ret, i;
+	int ret, i, retries = 0;
 
 	WARN_ON(__ieee80211_queue_pending(local, control->queue));
 
@@ -1181,6 +1181,13 @@ 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,

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