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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
Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/net/wireless/rt2x00/rt2x00dev.c
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@@ -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);