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mac80211: fix alternating-BSSID issue in IBSS

PATCH In review Vladimir Koutny 2 participants 3 messages Jul 1, 2008 – Jul 3, 2008 mac80211

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Vladimir Koutny

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#0 lore raw

PATCH 1/1 mac80211: fix alternating-BSSID issue in IBSS

Due to the fact that we (still) keep old BSS information, we can end up switching between 2 or more BSSIDs when in IBSS (these are the BSSIDs of networks with the same name we've seen before, even if they are not around anymore). This switching happens in 30sec intervals (IBSS merge attempt when no active STAs are around).

This patch expires old BSS entries after IEEE80211_SCAN_RESULT_EXPIRE seconds (the same time after it will not be reported in scan results) when trying to merge.

Signed-off-by Vladimir Koutny <[email protected]>

---

net/mac80211/mlme.c +24 -2
index 2b49852..b9ec4f6 100644
@@ -3276,12 +3276,32 @@ static void ieee80211_sta_expire(struct net_device *dev, unsigned long exp_time)
 }
 
 
+static void ieee80211_bss_expire(struct net_device *dev, unsigned long exp_time)
+{
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_sta_bss *bss, *tmp;
+	DECLARE_MAC_BUF(mac);
+
+	spin_lock_bh(&local->sta_bss_lock);
+	list_for_each_entry_safe(bss, tmp, &local->sta_bss_list, list) {
+		if (time_after(jiffies, bss->last_update + exp_time)) {
+#ifdef CONFIG_MAC80211_IBSS_DEBUG
+			printk(KERN_DEBUG "%s: expiring inactive BSS %s\n",
+				dev->name, print_mac(mac, bss->bssid));
+#endif /* CONFIG_MAC80211_IBSS_DEBUG */
+			ieee80211_rx_bss_put(dev, bss);
+		}
+	}
+	spin_unlock_bh(&local->sta_bss_lock);
+}
+
 static void ieee80211_sta_merge_ibss(struct net_device *dev,
 				     struct ieee80211_if_sta *ifsta)
 {
 	mod_timer(&ifsta->timer, jiffies + IEEE80211_IBSS_MERGE_INTERVAL);
 
 	ieee80211_sta_expire(dev, IEEE80211_IBSS_INACTIVITY_LIMIT);
+	ieee80211_bss_expire(dev, IEEE80211_SCAN_RESULT_EXPIRE);
 	if (ieee80211_sta_active_ibss(dev))
 		return;
 

@@ -3662,8 +3662,10 @@ static int ieee80211_sta_find_ibss(struct net_device *dev,
 	spin_unlock_bh(&local->sta_bss_lock);
 
 #ifdef CONFIG_MAC80211_IBSS_DEBUG
-	printk(KERN_DEBUG "   sta_find_ibss: selected %s current "
-	       "%s\n", print_mac(mac, bssid), print_mac(mac2, ifsta->bssid));
+	if (found)
+		printk(KERN_DEBUG "   sta_find_ibss: selected %s current "
+		       "%s\n", print_mac(mac, bssid),
+		       print_mac(mac2, ifsta->bssid));
 #endif /* CONFIG_MAC80211_IBSS_DEBUG */
 	if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0 &&
 	    (bss = ieee80211_rx_bss_get(dev, bssid,
#1 lore raw
Quoted 11 lines · Vladimir Koutny

Due to the fact that we (still) keep old BSS information, we can end up switching between 2 or more BSSIDs when in IBSS (these are the BSSIDs of networks with the same name we've seen before, even if they are not around anymore). This switching happens in 30sec intervals (IBSS merge attempt when no active STAs are around).

This patch expires old BSS entries after IEEE80211_SCAN_RESULT_EXPIRE seconds (the same time after it will not be reported in scan results) when trying to merge.

Signed-off-by Vladimir Koutny <[email protected]>

This seems like a good thing to do, but the sta_bss_list is used in STA mode too. Perhaps we should find a time to run ieee80211_bss_expire in STA mode as well?

net/mac80211/mlme.c static void ieee80211_sta_expire(struct net_device *dev, unsigned long exp_time) · line 3279

Quoted 12 lines

---

net/mac80211/mlme.c +1 -0
index 2b49852..b9ec4f6 100644
@@ -3276,12 +3276,32 @@ static void ieee80211_sta_expire(struct net_device *dev, unsigned long exp_time)
 }
 
 
+static void ieee80211_bss_expire(struct net_device *dev, unsigned long exp_time)

You probably want this positioned before (or after?) ieee80211_rx_bss_free, and change the name to match.

net/mac80211/mlme.c static void ieee80211_sta_expire(struct net_device *dev, unsigned long exp_time) · line 3288

Quoted 9 lines
net/mac80211/mlme.c +9 -0
+{
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_sta_bss *bss, *tmp;
+	DECLARE_MAC_BUF(mac);
+
+	spin_lock_bh(&local->sta_bss_lock);
+	list_for_each_entry_safe(bss, tmp, &local->sta_bss_list, list) {
+		if (time_after(jiffies, bss->last_update + exp_time)) {
+#ifdef CONFIG_MAC80211_IBSS_DEBUG

Since this hopefully won't be IBSS-specific, maybe use MAC80211_VERBOSE_DEBUG instead?

Quoted 22 lines
net/mac80211/mlme.c +10 -0
+			printk(KERN_DEBUG "%s: expiring inactive BSS %s\n",
+				dev->name, print_mac(mac, bss->bssid));
+#endif /* CONFIG_MAC80211_IBSS_DEBUG */
+			ieee80211_rx_bss_put(dev, bss);
+		}
+	}
+	spin_unlock_bh(&local->sta_bss_lock);
+}
+
 static void ieee80211_sta_merge_ibss(struct net_device *dev,
 				     struct ieee80211_if_sta *ifsta)
 {
 	mod_timer(&ifsta->timer, jiffies + IEEE80211_IBSS_MERGE_INTERVAL);
 
 	ieee80211_sta_expire(dev, IEEE80211_IBSS_INACTIVITY_LIMIT);
+	ieee80211_bss_expire(dev, IEEE80211_SCAN_RESULT_EXPIRE);
 	if (ieee80211_sta_active_ibss(dev))
 		return;
 

@@ -3662,8 +3662,10 @@ static int ieee80211_sta_find_ibss(struct net_device *dev,
 	spin_unlock_bh(&local->sta_bss_lock);

net/mac80211/mlme.c static int ieee80211_sta_find_ibss(struct net_device *dev, · line 3671

Quoted 10 lines
net/mac80211/mlme.c +4 -2
 #ifdef CONFIG_MAC80211_IBSS_DEBUG
-	printk(KERN_DEBUG "   sta_find_ibss: selected %s current "
-	       "%s\n", print_mac(mac, bssid), print_mac(mac2, ifsta->bssid));
+	if (found)
+		printk(KERN_DEBUG "   sta_find_ibss: selected %s current "
+		       "%s\n", print_mac(mac, bssid),
+		       print_mac(mac2, ifsta->bssid));
 #endif /* CONFIG_MAC80211_IBSS_DEBUG */
 	if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0 &&
 	    (bss = ieee80211_rx_bss_get(dev, bssid,

Should the last hunk be a different patch?

John

Signature · 2 lines
John W. Linville
[email protected]
author
#2 lore raw
Quoted 11 lines · John W. Linville
Quoted 10 lines · Vladimir Koutny

Due to the fact that we (still) keep old BSS information, we can end up switching between 2 or more BSSIDs when in IBSS (these are the BSSIDs of networks with the same name we've seen before, even if they are not around anymore). This switching happens in 30sec intervals (IBSS merge attempt when no active STAs are around).

This patch expires old BSS entries after IEEE80211_SCAN_RESULT_EXPIRE seconds (the same time after it will not be reported in scan results) when trying to merge.

Quoted 5 lines
Quoted 1 line
Signed-off-by Vladimir Koutny <[email protected]>

This seems like a good thing to do, but the sta_bss_list is used in STA mode too. Perhaps we should find a time to run ieee80211_bss_expire in STA mode as well?

Yes, probably. Any suggestions for a suitable place? (I'm not that familiar with the code..) It should probably be done on some timer (and probably also right before we try to associate?)..

Quoted 4 lines
Quoted 1 line

+static void ieee80211_bss_expire(struct net_device *dev, unsigned long exp_time)

You probably want this positioned before (or after?) ieee80211_rx_bss_free, and change the name to match.

OK, moved and renamed to ieee80211_rx_bss_expire.

Quoted 15 lines

net/mac80211/mlme.c static int ieee80211_sta_find_ibss(struct net_device *dev, · line 3671

Quoted 13 lines
net/mac80211/mlme.c +4 -2
@@ -3662,8 +3662,10 @@ static int ieee80211_sta_find_ibss(struct net_device *dev,
 	spin_unlock_bh(&local->sta_bss_lock);
 
 #ifdef CONFIG_MAC80211_IBSS_DEBUG
-	printk(KERN_DEBUG "   sta_find_ibss: selected %s current "
-	       "%s\n", print_mac(mac, bssid), print_mac(mac2, ifsta->bssid));
+	if (found)
+		printk(KERN_DEBUG "   sta_find_ibss: selected %s current "
+		       "%s\n", print_mac(mac, bssid),
+		       print_mac(mac2, ifsta->bssid));
 #endif /* CONFIG_MAC80211_IBSS_DEBUG */
 	if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0 &&
 	    (bss = ieee80211_rx_bss_get(dev, bssid,

Should the last hunk be a different patch?

Oops - I've found this out at the same time I was doing the rest and I kept it in the same patch.. I'll split this.

Vladimir

Quoted 2 lines

John