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rt2x00: Fix for race condition while update beacon

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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>
This commit is contained in:
Igor Perminov
2009-08-08 23:55:18 +02:00
committed by John W. Linville
parent 66679a65ef
commit 17512dc3b7
4 changed files with 20 additions and 8 deletions
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1
drivers/net/wireless/rt2x00/rt2x00mac.c
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@@ -274,6 +274,7 @@ int rt2x00mac_add_interface(struct ieee80211_hw *hw,
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)