mac80211: add beacon configuration via cfg80211
This patch implements the cfg80211 hooks for configuring beaconing
on an access point interface in mac80211. While doing so, it fixes
a number of races that could badly crash the machine when the
beacon is changed while being requested by the driver.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 99590e4..51c0f00 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1628,7 +1628,8 @@
static void ieee80211_beacon_add_tim(struct ieee80211_local *local,
struct ieee80211_if_ap *bss,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ struct beacon_data *beacon)
{
u8 *pos, *tim;
int aid0 = 0;
@@ -1644,7 +1645,7 @@
IEEE80211_MAX_AID+1);
if (bss->dtim_count == 0)
- bss->dtim_count = bss->dtim_period - 1;
+ bss->dtim_count = beacon->dtim_period - 1;
else
bss->dtim_count--;
@@ -1652,7 +1653,7 @@
*pos++ = WLAN_EID_TIM;
*pos++ = 4;
*pos++ = bss->dtim_count;
- *pos++ = bss->dtim_period;
+ *pos++ = beacon->dtim_period;
if (bss->dtim_count == 0 && !skb_queue_empty(&bss->ps_bc_buf))
aid0 = 1;
@@ -1700,44 +1701,43 @@
struct ieee80211_sub_if_data *sdata = NULL;
struct ieee80211_if_ap *ap = NULL;
struct rate_selection rsel;
- u8 *b_head, *b_tail;
- int bh_len, bt_len;
+ struct beacon_data *beacon;
+
+ rcu_read_lock();
sdata = vif_to_sdata(vif);
bdev = sdata->dev;
ap = &sdata->u.ap;
- if (!ap || sdata->vif.type != IEEE80211_IF_TYPE_AP ||
- !ap->beacon_head) {
+ beacon = rcu_dereference(ap->beacon);
+
+ if (!ap || sdata->vif.type != IEEE80211_IF_TYPE_AP || !beacon) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
if (net_ratelimit())
printk(KERN_DEBUG "no beacon data avail for %s\n",
bdev->name);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
- return NULL;
+ skb = NULL;
+ goto out;
}
- /* Assume we are generating the normal beacon locally */
- b_head = ap->beacon_head;
- b_tail = ap->beacon_tail;
- bh_len = ap->beacon_head_len;
- bt_len = ap->beacon_tail_len;
-
- skb = dev_alloc_skb(local->tx_headroom +
- bh_len + bt_len + 256 /* maximum TIM len */);
+ /* headroom, head length, tail length and maximum TIM length */
+ skb = dev_alloc_skb(local->tx_headroom + beacon->head_len +
+ beacon->tail_len + 256);
if (!skb)
- return NULL;
+ goto out;
skb_reserve(skb, local->tx_headroom);
- memcpy(skb_put(skb, bh_len), b_head, bh_len);
+ memcpy(skb_put(skb, beacon->head_len), beacon->head,
+ beacon->head_len);
ieee80211_include_sequence(sdata, (struct ieee80211_hdr *)skb->data);
- ieee80211_beacon_add_tim(local, ap, skb);
+ ieee80211_beacon_add_tim(local, ap, skb, beacon);
- if (b_tail) {
- memcpy(skb_put(skb, bt_len), b_tail, bt_len);
- }
+ if (beacon->tail)
+ memcpy(skb_put(skb, beacon->tail_len), beacon->tail,
+ beacon->tail_len);
if (control) {
rate_control_get_rate(local->mdev, local->oper_hw_mode, skb,
@@ -1749,7 +1749,8 @@
wiphy_name(local->hw.wiphy));
}
dev_kfree_skb(skb);
- return NULL;
+ skb = NULL;
+ goto out;
}
control->tx_rate =
@@ -1764,6 +1765,9 @@
}
ap->num_beacons++;
+
+ out:
+ rcu_read_unlock();
return skb;
}
EXPORT_SYMBOL(ieee80211_beacon_get);
@@ -1815,14 +1819,25 @@
struct net_device *bdev;
struct ieee80211_sub_if_data *sdata;
struct ieee80211_if_ap *bss = NULL;
+ struct beacon_data *beacon;
sdata = vif_to_sdata(vif);
bdev = sdata->dev;
- if (!bss || sdata->vif.type != IEEE80211_IF_TYPE_AP ||
- !bss->beacon_head)
+
+ if (!bss)
return NULL;
+ rcu_read_lock();
+ beacon = rcu_dereference(bss->beacon);
+
+ if (sdata->vif.type != IEEE80211_IF_TYPE_AP || !beacon ||
+ !beacon->head) {
+ rcu_read_unlock();
+ return NULL;
+ }
+ rcu_read_unlock();
+
if (bss->dtim_count != 0)
return NULL; /* send buffered bc/mc only after DTIM beacon */
memset(control, 0, sizeof(*control));