mac80211: proper STA info locking

As discussed earlier, we can unify locking in struct sta_info
and use just a single spinlock protecting all members of the
structure that need protection. Many don't, but one of the
especially bad ones is the 'flags' member that can currently
be clobbered when RX and TX is being processed on different
CPUs at the same time.

Because having four spinlocks for different, mostly exclusive
parts of a single structure is overkill, this patch also kills
the ampdu and mesh plink spinlocks and uses just a single one
for everything. Because none of the spinlocks are nested, this
is safe.

It remains to be seen whether or not we should make the sta
flags use atomic bit operations instead, for now though this
is a safe thing and using atomic operations instead will be
very simple using the new static inline functions this patch
introduces for accessing sta->flags.

Since spin_lock_bh() is used with this lock, there shouldn't
be any contention even if aggregation is enabled at around the
same time as both requires frame transmission/reception which
is in a bh context.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Tomas Winkler <tomasw@gmail.com>
Cc: Ron Rindjunsky <ron.rindjunsky@intel.com>
Cc: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 8 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index e8b89c89e875..b399e09ec7aa 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -479,7 +479,7 @@ ieee80211_rx_h_check(struct ieee80211_rx_data *rx)
 		      ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_CTL &&
 		       (rx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)) &&
 		     rx->sdata->vif.type != IEEE80211_IF_TYPE_IBSS &&
-		     (!rx->sta || !(rx->sta->flags & WLAN_STA_ASSOC)))) {
+		     (!rx->sta || !test_sta_flags(rx->sta, WLAN_STA_ASSOC)))) {
 		if ((!(rx->fc & IEEE80211_FCTL_FROMDS) &&
 		     !(rx->fc & IEEE80211_FCTL_TODS) &&
 		     (rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA)
@@ -630,8 +630,7 @@ static void ap_sta_ps_start(struct net_device *dev, struct sta_info *sta)
 
 	if (sdata->bss)
 		atomic_inc(&sdata->bss->num_sta_ps);
-	sta->flags |= WLAN_STA_PS;
-	sta->flags &= ~WLAN_STA_PSPOLL;
+	set_and_clear_sta_flags(sta, WLAN_STA_PS, WLAN_STA_PSPOLL);
 #ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
 	printk(KERN_DEBUG "%s: STA %s aid %d enters power save mode\n",
 	       dev->name, print_mac(mac, sta->addr), sta->aid);
@@ -652,7 +651,7 @@ static int ap_sta_ps_end(struct net_device *dev, struct sta_info *sta)
 	if (sdata->bss)
 		atomic_dec(&sdata->bss->num_sta_ps);
 
-	sta->flags &= ~(WLAN_STA_PS | WLAN_STA_PSPOLL);
+	clear_sta_flags(sta, WLAN_STA_PS | WLAN_STA_PSPOLL);
 
 	if (!skb_queue_empty(&sta->ps_tx_buf))
 		sta_info_clear_tim_bit(sta);
@@ -727,9 +726,10 @@ ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
 	if (!(rx->fc & IEEE80211_FCTL_MOREFRAGS)) {
 		/* Change STA power saving mode only in the end of a frame
 		 * exchange sequence */
-		if ((sta->flags & WLAN_STA_PS) && !(rx->fc & IEEE80211_FCTL_PM))
+		if (test_sta_flags(sta, WLAN_STA_PS) &&
+		    !(rx->fc & IEEE80211_FCTL_PM))
 			rx->sent_ps_buffered += ap_sta_ps_end(dev, sta);
-		else if (!(sta->flags & WLAN_STA_PS) &&
+		else if (!test_sta_flags(sta, WLAN_STA_PS) &&
 			 (rx->fc & IEEE80211_FCTL_PM))
 			ap_sta_ps_start(dev, sta);
 	}
@@ -983,7 +983,7 @@ ieee80211_rx_h_ps_poll(struct ieee80211_rx_data *rx)
 		 * Tell TX path to send one frame even though the STA may
 		 * still remain is PS mode after this frame exchange.
 		 */
-		rx->sta->flags |= WLAN_STA_PSPOLL;
+		set_sta_flags(rx->sta, WLAN_STA_PSPOLL);
 
 #ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
 		printk(KERN_DEBUG "STA %s aid %d: PS Poll (entries after %d)\n",
@@ -1046,7 +1046,8 @@ ieee80211_rx_h_remove_qos_control(struct ieee80211_rx_data *rx)
 static int
 ieee80211_802_1x_port_control(struct ieee80211_rx_data *rx)
 {
-	if (unlikely(!rx->sta || !(rx->sta->flags & WLAN_STA_AUTHORIZED))) {
+	if (unlikely(!rx->sta ||
+	    !test_sta_flags(rx->sta, WLAN_STA_AUTHORIZED))) {
 #ifdef CONFIG_MAC80211_DEBUG
 		if (net_ratelimit())
 			printk(KERN_DEBUG "%s: dropped frame "