rt2x00: Fix for race condition while update beacon
The patch "Implement set_tim callback for all drivers" can cause kernel
oops in rt73usb_write_beacon. The oops is caused by one of the following
race conditions:
* In case of two near calls to set_tim: rt2x00lib_beacondone_iter is
cleaning the beacon skb, whereas rt73usb_write_beacon is still using it.
* In case of two near updates of beacon: first as the result of set_tim
and second as the result of a call from an application (e.g. hostapd).
This patch fixes the race condition by rearranging the update logic and
guarding rt2x00_intf->beacon->skb with a mutex.
Signed-off-by: Igor Perminov <igor.perminov@inbox.ru>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c
index 4164fce..74451f9 100644
--- a/drivers/net/wireless/rt2x00/rt2x00mac.c
+++ b/drivers/net/wireless/rt2x00/rt2x00mac.c
@@ -274,6 +274,7 @@
spin_lock_init(&intf->lock);
spin_lock_init(&intf->seqlock);
+ mutex_init(&intf->beacon_skb_mutex);
intf->beacon = entry;
if (conf->type == NL80211_IFTYPE_AP)