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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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5
drivers/net/wireless/rt2x00/rt2x00.h
View File

@ -333,6 +333,11 @@ struct rt2x00_intf {
*/
u8 bssid[ETH_ALEN];
/*
* beacon->skb must be protected with the mutex.
*/
struct mutex beacon_skb_mutex;
/*
* Entry in the beacon queue which belongs to
* this interface. Each interface has its own

7
drivers/net/wireless/rt2x00/rt2x00dev.c
View File

@ -186,7 +186,6 @@ static void rt2x00lib_intf_scheduled(struct work_struct *work)
static void rt2x00lib_beacondone_iter(void *data, u8 *mac,
struct ieee80211_vif *vif)
{
struct rt2x00_dev *rt2x00dev = data;
struct rt2x00_intf *intf = vif_to_intf(vif);
if (vif->type != NL80211_IFTYPE_AP &&
@ -195,12 +194,6 @@ static void rt2x00lib_beacondone_iter(void *data, u8 *mac,
vif->type != NL80211_IFTYPE_WDS)
return;
/*
* Clean up the beacon skb.
*/
rt2x00queue_free_skb(rt2x00dev, intf->beacon->skb);
intf->beacon->skb = NULL;
spin_lock(&intf->lock);
intf->delayed_flags |= DELAYED_UPDATE_BEACON;
spin_unlock(&intf->lock);

1
drivers/net/wireless/rt2x00/rt2x00mac.c
View File

@ -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)

15
drivers/net/wireless/rt2x00/rt2x00queue.c
View File

@ -503,14 +503,25 @@ int rt2x00queue_update_beacon(struct rt2x00_dev *rt2x00dev,
if (unlikely(!intf->beacon))
return -ENOBUFS;
mutex_lock(&intf->beacon_skb_mutex);
/*
* Clean up the beacon skb.
*/
rt2x00queue_free_skb(rt2x00dev, intf->beacon->skb);
intf->beacon->skb = NULL;
if (!enable_beacon) {
rt2x00dev->ops->lib->kill_tx_queue(rt2x00dev, QID_BEACON);
mutex_unlock(&intf->beacon_skb_mutex);
return 0;
}
intf->beacon->skb = ieee80211_beacon_get(rt2x00dev->hw, vif);
if (!intf->beacon->skb)
if (!intf->beacon->skb) {
mutex_unlock(&intf->beacon_skb_mutex);
return -ENOMEM;
}
/*
* Copy all TX descriptor information into txdesc,
@ -548,6 +559,8 @@ int rt2x00queue_update_beacon(struct rt2x00_dev *rt2x00dev,
rt2x00dev->ops->lib->write_beacon(intf->beacon);
rt2x00dev->ops->lib->kick_tx_queue(rt2x00dev, QID_BEACON);
mutex_unlock(&intf->beacon_skb_mutex);
return 0;
}