[MAC80211]: improve locking of sta_info related structures

The sta_info code has some awkward locking which prevents some driver
callbacks from being allowed to sleep. This patch makes the locking more
focused so code that calls driver callbacks are allowed to sleep. It also
converts sta_lock to a rwlock.

Signed-off-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 14 insertions, 6 deletions

diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
index 0d99b685df5f..9aee1abae127 100644
--- a/net/mac80211/ieee80211_sta.c
+++ b/net/mac80211/ieee80211_sta.c
@@ -773,7 +773,7 @@ static void ieee80211_associated(struct net_device *dev,
                                        "range\n",
                                        dev->name, MAC_ARG(ifsta->bssid));
                                 disassoc = 1;
-                                sta_info_free(sta, 0);
+                                sta_info_free(sta);
                                 ifsta->probereq_poll = 0;
                         } else {
                                 ieee80211_send_probe_req(dev, ifsta->bssid,
@@ -1890,7 +1890,7 @@ static int ieee80211_sta_active_ibss(struct net_device *dev)
         int active = 0;
         struct sta_info *sta;
 
-        spin_lock_bh(&local->sta_lock);
+        read_lock_bh(&local->sta_lock);
         list_for_each_entry(sta, &local->sta_list, list) {
                 if (sta->dev == dev &&
                     time_after(sta->last_rx + IEEE80211_IBSS_MERGE_INTERVAL,
@@ -1899,7 +1899,7 @@ static int ieee80211_sta_active_ibss(struct net_device *dev)
                         break;
                 }
         }
-        spin_unlock_bh(&local->sta_lock);
+        read_unlock_bh(&local->sta_lock);
 
         return active;
 }
@@ -1909,16 +1909,24 @@ static void ieee80211_sta_expire(struct net_device *dev)
 {
         struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
         struct sta_info *sta, *tmp;
+        LIST_HEAD(tmp_list);
 
-        spin_lock_bh(&local->sta_lock);
+        write_lock_bh(&local->sta_lock);
         list_for_each_entry_safe(sta, tmp, &local->sta_list, list)
                 if (time_after(jiffies, sta->last_rx +
                                IEEE80211_IBSS_INACTIVITY_LIMIT)) {
                         printk(KERN_DEBUG "%s: expiring inactive STA " MAC_FMT
                                "\n", dev->name, MAC_ARG(sta->addr));
-                        sta_info_free(sta, 1);
+                        __sta_info_get(sta);
+                        sta_info_remove(sta);
+                        list_add(&sta->list, &tmp_list);
                 }
-        spin_unlock_bh(&local->sta_lock);
+        write_unlock_bh(&local->sta_lock);
+
+        list_for_each_entry_safe(sta, tmp, &tmp_list, list) {
+                sta_info_free(sta);
+                sta_info_put(sta);
+        }
 }