[2.6.20.17 review 51/58] softmac: Fix deadlock of wx_set_essid with assoc work

[Willy Tarreau]

The essid wireless extension does deadlock against the assoc mutex,
as we don't unlock the assoc mutex when flushing the workqueue, which
also holds the lock.

Signed-off-by: Michael Buesch <mb@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 net/ieee80211/softmac/ieee80211softmac_wx.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/net/ieee80211/softmac/ieee80211softmac_wx.c b/net/ieee80211/softmac/ieee80211softmac_wx.c
index fb58e03..c3c39ed 100644
--- a/net/ieee80211/softmac/ieee80211softmac_wx.c
+++ b/net/ieee80211/softmac/ieee80211softmac_wx.c
@@ -74,8 +74,8 @@ ieee80211softmac_wx_set_essid(struct net_device *net_dev,
 	struct ieee80211softmac_auth_queue_item *authptr;
 	int length = 0;
 
+check_assoc_again:
 	mutex_lock(&sm->associnfo.mutex);
-
 	/* Check if we're already associating to this or another network
 	 * If it's another network, cancel and start over with our new network
 	 * If it's our network, ignore the change, we're already doing it!
@@ -98,13 +98,18 @@ ieee80211softmac_wx_set_essid(struct net_device *net_dev,
 				cancel_delayed_work(&authptr->work);
 			sm->associnfo.bssvalid = 0;
 			sm->associnfo.bssfixed = 0;
-			flush_scheduled_work();
 			sm->associnfo.associating = 0;
 			sm->associnfo.associated = 0;
+			/* We must unlock to avoid deadlocks with the assoc workqueue
+			 * on the associnfo.mutex */
+			mutex_unlock(&sm->associnfo.mutex);
+			flush_scheduled_work();
+			/* Avoid race! Check assoc status again. Maybe someone started an
+			 * association while we flushed. */
+			goto check_assoc_again;
 		}
 	}
 
-
 	sm->associnfo.static_essid = 0;
 	sm->associnfo.assoc_wait = 0;
 
-- 
1.5.2.5

-- 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/