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[PATCH] mac80211: fix virtual interface locking

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Florian Lohoff noticed a bug in mac80211: when bringing the
master interface down while other virtual interfaces are up
we call dev_close() under a spinlock which is not allowed.
This patch removes the sub_if_lock used by mac80211 in favour
of using an RCU list. All list manipulations are already done
under rtnl so are well protected against each other, and the
read-side locks we took in the RX and TX code are already in
RCU read-side critical sections.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Florian Lohoff <flo@rfc822.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Johannes Berg
2007-09-18 17:29:21 -04:00
committed by David S. Miller
parent ea49c359f3
commit 79010420cc
6 changed files with 58 additions and 65 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
net/mac80211/ieee80211.c
View File

@ -93,14 +93,13 @@ static int ieee80211_master_open(struct net_device *dev)
struct ieee80211_sub_if_data *sdata;
int res = -EOPNOTSUPP;
read_lock(&local->sub_if_lock);
list_for_each_entry(sdata, &local->sub_if_list, list) {
/* we hold the RTNL here so can safely walk the list */
list_for_each_entry(sdata, &local->interfaces, list) {
if (sdata->dev != dev && netif_running(sdata->dev)) {
res = 0;
break;
}
}
read_unlock(&local->sub_if_lock);
return res;
}
@ -109,11 +108,10 @@ static int ieee80211_master_stop(struct net_device *dev)
struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
struct ieee80211_sub_if_data *sdata;
read_lock(&local->sub_if_lock);
list_for_each_entry(sdata, &local->sub_if_list, list)
/* we hold the RTNL here so can safely walk the list */
list_for_each_entry(sdata, &local->interfaces, list)
if (sdata->dev != dev && netif_running(sdata->dev))
dev_close(sdata->dev);
read_unlock(&local->sub_if_lock);
return 0;
}
@ -315,8 +313,8 @@ static int ieee80211_open(struct net_device *dev)
sdata = IEEE80211_DEV_TO_SUB_IF(dev);
read_lock(&local->sub_if_lock);
list_for_each_entry(nsdata, &local->sub_if_list, list) {
/* we hold the RTNL here so can safely walk the list */
list_for_each_entry(nsdata, &local->interfaces, list) {
struct net_device *ndev = nsdata->dev;
if (ndev != dev && ndev != local->mdev && netif_running(ndev) &&
@ -325,10 +323,8 @@ static int ieee80211_open(struct net_device *dev)
* check whether it may have the same address
*/
if (!identical_mac_addr_allowed(sdata->type,
nsdata->type)) {
read_unlock(&local->sub_if_lock);
nsdata->type))
return -ENOTUNIQ;
}
/*
* can only add VLANs to enabled APs
@ -339,7 +335,6 @@ static int ieee80211_open(struct net_device *dev)
sdata->u.vlan.ap = nsdata;
}
}
read_unlock(&local->sub_if_lock);
switch (sdata->type) {
case IEEE80211_IF_TYPE_WDS:
@ -466,14 +461,13 @@ static int ieee80211_stop(struct net_device *dev)
sdata->u.sta.state = IEEE80211_DISABLED;
del_timer_sync(&sdata->u.sta.timer);
/*
* Holding the sub_if_lock for writing here blocks
* out the receive path and makes sure it's not
* currently processing a packet that may get
* added to the queue.
* When we get here, the interface is marked down.
* Call synchronize_rcu() to wait for the RX path
* should it be using the interface and enqueuing
* frames at this very time on another CPU.
*/
write_lock_bh(&local->sub_if_lock);
synchronize_rcu();
skb_queue_purge(&sdata->u.sta.skb_queue);
write_unlock_bh(&local->sub_if_lock);
if (!local->ops->hw_scan &&
local->scan_dev == sdata->dev) {
@ -1033,9 +1027,9 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
rthdr->data_retries = status->retry_count;
read_lock(&local->sub_if_lock);
rcu_read_lock();
monitors = local->monitors;
list_for_each_entry(sdata, &local->sub_if_list, list) {
list_for_each_entry_rcu(sdata, &local->interfaces, list) {
/*
* Using the monitors counter is possibly racy, but
* if the value is wrong we simply either clone the skb
@ -1051,7 +1045,7 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
continue;
monitors--;
if (monitors)
skb2 = skb_clone(skb, GFP_KERNEL);
skb2 = skb_clone(skb, GFP_ATOMIC);
else
skb2 = NULL;
skb->dev = sdata->dev;
@ -1066,7 +1060,7 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
}
}
out:
read_unlock(&local->sub_if_lock);
rcu_read_unlock();
if (skb)
dev_kfree_skb(skb);
}
@ -1154,8 +1148,7 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
INIT_LIST_HEAD(&local->modes_list);
rwlock_init(&local->sub_if_lock);
INIT_LIST_HEAD(&local->sub_if_list);
INIT_LIST_HEAD(&local->interfaces);
INIT_DELAYED_WORK(&local->scan_work, ieee80211_sta_scan_work);
ieee80211_rx_bss_list_init(mdev);
@ -1175,7 +1168,8 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
sdata->u.ap.force_unicast_rateidx = -1;
sdata->u.ap.max_ratectrl_rateidx = -1;
ieee80211_if_sdata_init(sdata);
list_add_tail(&sdata->list, &local->sub_if_list);
/* no RCU needed since we're still during init phase */
list_add_tail(&sdata->list, &local->interfaces);
tasklet_init(&local->tx_pending_tasklet, ieee80211_tx_pending,
(unsigned long)local);
@ -1334,7 +1328,6 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
{
struct ieee80211_local *local = hw_to_local(hw);
struct ieee80211_sub_if_data *sdata, *tmp;
struct list_head tmp_list;
int i;
tasklet_kill(&local->tx_pending_tasklet);
@ -1348,11 +1341,12 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
if (local->apdev)
ieee80211_if_del_mgmt(local);
write_lock_bh(&local->sub_if_lock);
list_replace_init(&local->sub_if_list, &tmp_list);
write_unlock_bh(&local->sub_if_lock);
list_for_each_entry_safe(sdata, tmp, &tmp_list, list)
/*
* At this point, interface list manipulations are fine
* because the driver cannot be handing us frames any
* more and the tasklet is killed.
*/
list_for_each_entry_safe(sdata, tmp, &local->interfaces, list)
__ieee80211_if_del(local, sdata);
rtnl_unlock();