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

Willy Tarreau
2007-08-22T09:05:03Z

[-- Attachment #1: 0051-softmac-Fix-deadlock-of-wx_set_essid-with-assoc-wor.patch --]
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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@bu3sch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
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

--