From: Johannes Berg <johannes@sipsolutions.net>
Date: Wed, 18 Jun 2008 22:39:48 +0000 (-0700)
Subject: mac80211: detect driver tx bugs
X-Git-Tag: v2.6.26-rc8~24^2~5
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ef3a62d272f033989e83eb1f26505f93f93e3e69;p=linux-2.6

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>
---

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 28d8bd53bd..c80d5899f2 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,