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

From: Greg KH
Date: Tue Jul 22 2008 - 19:19:10 EST

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

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

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)) {
+ 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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