mac80211: refactor station state transitions

Station entries can have various states, the most
important ones being auth, assoc and authorized.
This patch prepares us for telling the driver about
these states, we don't want to confuse drivers with
strange transitions, so with this we enforce that
they move in the right order between them (back and
forth); some transitions might happen before the
driver even knows about the station, but at least
runtime transitions will be ordered correctly.

As a consequence, IBSS and MESH stations will now
have the ASSOC flag set (so they can transition to
AUTHORIZED), and we can get rid of a special case
in TX processing.

When freeing a station, unwind the state so that
other parts of the code (or drivers later) can rely
on the transitions.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 59 insertions, 6 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index c6ca9bd81add..b22775cdcdf5 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -204,16 +204,17 @@ struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata,
 }
 
 /**
- * __sta_info_free - internal STA free helper
+ * sta_info_free - free STA
  *
  * @local: pointer to the global information
  * @sta: STA info to free
  *
  * This function must undo everything done by sta_info_alloc()
- * that may happen before sta_info_insert().
+ * that may happen before sta_info_insert(). It may only be
+ * called when sta_info_insert() has not been attempted (and
+ * if that fails, the station is freed anyway.)
  */
-static void __sta_info_free(struct ieee80211_local *local,
-			    struct sta_info *sta)
+void sta_info_free(struct ieee80211_local *local, struct sta_info *sta)
 {
 	if (sta->rate_ctrl) {
 		rate_control_free_sta(sta);
@@ -598,7 +599,7 @@ int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU)
 	return 0;
  out_free:
 	BUG_ON(!err);
-	__sta_info_free(local, sta);
+	sta_info_free(local, sta);
 	return err;
 }
 
@@ -905,6 +906,9 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
 	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 		RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);
 
+	while (sta->sta_state > IEEE80211_STA_NONE)
+		sta_info_move_state(sta, sta->sta_state - 1);
+
 	if (sta->uploaded) {
 		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 			sdata = container_of(sdata->bss,
@@ -974,7 +978,7 @@ static int __must_check __sta_info_destroy(struct sta_info *sta)
 		kfree_rcu(tid_tx, rcu_head);
 	}
 
-	__sta_info_free(local, sta);
+	sta_info_free(local, sta);
 
 	return 0;
 }
@@ -1538,3 +1542,52 @@ void ieee80211_sta_set_buffered(struct ieee80211_sta *pubsta,
 	sta_info_recalc_tim(sta);
 }
 EXPORT_SYMBOL(ieee80211_sta_set_buffered);
+
+int sta_info_move_state_checked(struct sta_info *sta,
+				enum ieee80211_sta_state new_state)
+{
+	/* might_sleep(); -- for driver notify later, fix IBSS first */
+
+	if (sta->sta_state == new_state)
+		return 0;
+
+	switch (new_state) {
+	case IEEE80211_STA_NONE:
+		if (sta->sta_state == IEEE80211_STA_AUTH)
+			clear_bit(WLAN_STA_AUTH, &sta->_flags);
+		else
+			return -EINVAL;
+		break;
+	case IEEE80211_STA_AUTH:
+		if (sta->sta_state == IEEE80211_STA_NONE)
+			set_bit(WLAN_STA_AUTH, &sta->_flags);
+		else if (sta->sta_state == IEEE80211_STA_ASSOC)
+			clear_bit(WLAN_STA_ASSOC, &sta->_flags);
+		else
+			return -EINVAL;
+		break;
+	case IEEE80211_STA_ASSOC:
+		if (sta->sta_state == IEEE80211_STA_AUTH)
+			set_bit(WLAN_STA_ASSOC, &sta->_flags);
+		else if (sta->sta_state == IEEE80211_STA_AUTHORIZED)
+			clear_bit(WLAN_STA_AUTHORIZED, &sta->_flags);
+		else
+			return -EINVAL;
+		break;
+	case IEEE80211_STA_AUTHORIZED:
+		if (sta->sta_state == IEEE80211_STA_ASSOC)
+			set_bit(WLAN_STA_AUTHORIZED, &sta->_flags);
+		else
+			return -EINVAL;
+		break;
+	default:
+		WARN(1, "invalid state %d", new_state);
+		return -EINVAL;
+	}
+
+	printk(KERN_DEBUG "%s: moving STA %pM to state %d\n",
+		sta->sdata->name, sta->sta.addr, new_state);
+	sta->sta_state = new_state;
+
+	return 0;
+}