From 17512dc3b7fc9ff1a60d3748ce87c323df507c3d Mon Sep 17 00:00:00 2001 From: Igor Perminov Date: Sat, 8 Aug 2009 23:55:18 +0200 Subject: [PATCH] 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 Signed-off-by: Ivo van Doorn Signed-off-by: John W. Linville --- drivers/net/wireless/rt2x00/rt2x00.h | 5 +++++ drivers/net/wireless/rt2x00/rt2x00dev.c | 7 ------- drivers/net/wireless/rt2x00/rt2x00mac.c | 1 + drivers/net/wireless/rt2x00/rt2x00queue.c | 15 ++++++++++++++- 4 files changed, 20 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h index e6e73be31e37..7c74c4efcb0f 100644 --- a/drivers/net/wireless/rt2x00/rt2x00.h +++ b/drivers/net/wireless/rt2x00/rt2x00.h @@ -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 diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c index e0348cc22d16..b6676c6722fc 100644 --- a/drivers/net/wireless/rt2x00/rt2x00dev.c +++ b/drivers/net/wireless/rt2x00/rt2x00dev.c @@ -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); diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c index 4164fce05987..74451f9672d9 100644 --- a/drivers/net/wireless/rt2x00/rt2x00mac.c +++ b/drivers/net/wireless/rt2x00/rt2x00mac.c @@ -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) diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c index e67e339d9dfd..06af823efd83 100644 --- a/drivers/net/wireless/rt2x00/rt2x00queue.c +++ b/drivers/net/wireless/rt2x00/rt2x00queue.c @@ -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; } -- 2.20.1