mac80211: support runtime interface type changes

Add support to mac80211 for changing the interface
type even when the interface is UP, if the driver
supports it.

To achieve this
 * add a new driver callback for switching,
 * split some of the interface up/down code out
   into new functions (do_open/do_stop), and
 * maintain an own __SDATA_RUNNING bit that will
   not be set during interface type, so that any
   other code doesn't use the interface.

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

1 files changed, 124 insertions, 33 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index cba3d806d722..c1cc200ac81f 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -148,7 +148,12 @@ static int ieee80211_check_concurrent_iface(struct ieee80211_sub_if_data *sdata,
         return 0;
 }
 
-static int ieee80211_open(struct net_device *dev)
+/*
+ * NOTE: Be very careful when changing this function, it must NOT return
+ * an error on interface type changes that have been pre-checked, so most
+ * checks should be in ieee80211_check_concurrent_iface.
+ */
+static int ieee80211_do_open(struct net_device *dev, bool coming_up)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         struct ieee80211_local *local = sdata->local;
@@ -157,15 +162,6 @@ static int ieee80211_open(struct net_device *dev)
         int res;
         u32 hw_reconf_flags = 0;
 
-        /* fail early if user set an invalid address */
-        if (!is_zero_ether_addr(dev->dev_addr) &&
-            !is_valid_ether_addr(dev->dev_addr))
-                return -EADDRNOTAVAIL;
-
-        res = ieee80211_check_concurrent_iface(sdata, sdata->vif.type);
-        if (res)
-                return res;
-
         switch (sdata->vif.type) {
         case NL80211_IFTYPE_WDS:
                 if (!is_valid_ether_addr(sdata->u.wds.remote_addr))
@@ -258,9 +254,11 @@ static int ieee80211_open(struct net_device *dev)
                 netif_carrier_on(dev);
                 break;
         default:
-                res = drv_add_interface(local, &sdata->vif);
-                if (res)
-                        goto err_stop;
+                if (coming_up) {
+                        res = drv_add_interface(local, &sdata->vif);
+                        if (res)
+                                goto err_stop;
+                }
 
                 if (ieee80211_vif_is_mesh(&sdata->vif)) {
                         local->fif_other_bss++;
@@ -316,7 +314,9 @@ static int ieee80211_open(struct net_device *dev)
         hw_reconf_flags |= __ieee80211_recalc_idle(local);
         mutex_unlock(&local->mtx);
 
-        local->open_count++;
+        if (coming_up)
+                local->open_count++;
+
         if (hw_reconf_flags) {
                 ieee80211_hw_config(local, hw_reconf_flags);
                 /*
@@ -331,6 +331,8 @@ static int ieee80211_open(struct net_device *dev)
 
         netif_tx_start_all_queues(dev);
 
+        set_bit(SDATA_STATE_RUNNING, &sdata->state);
+
         return 0;
  err_del_interface:
         drv_remove_interface(local, &sdata->vif);
@@ -344,19 +346,38 @@ static int ieee80211_open(struct net_device *dev)
         return res;
 }
 
-static int ieee80211_stop(struct net_device *dev)
+static int ieee80211_open(struct net_device *dev)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+        int err;
+
+        /* fail early if user set an invalid address */
+        if (!is_zero_ether_addr(dev->dev_addr) &&
+            !is_valid_ether_addr(dev->dev_addr))
+                return -EADDRNOTAVAIL;
+
+        err = ieee80211_check_concurrent_iface(sdata, sdata->vif.type);
+        if (err)
+                return err;
+
+        return ieee80211_do_open(dev, true);
+}
+
+static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
+                              bool going_down)
+{
         struct ieee80211_local *local = sdata->local;
         unsigned long flags;
         struct sk_buff *skb, *tmp;
         u32 hw_reconf_flags = 0;
         int i;
 
+        clear_bit(SDATA_STATE_RUNNING, &sdata->state);
+
         /*
          * Stop TX on this interface first.
          */
-        netif_tx_stop_all_queues(dev);
+        netif_tx_stop_all_queues(sdata->dev);
 
         /*
          * Purge work for this interface.
@@ -394,11 +415,12 @@ static int ieee80211_stop(struct net_device *dev)
         if (sdata->vif.type == NL80211_IFTYPE_AP)
                 local->fif_pspoll--;
 
-        netif_addr_lock_bh(dev);
+        netif_addr_lock_bh(sdata->dev);
         spin_lock_bh(&local->filter_lock);
-        __hw_addr_unsync(&local->mc_list, &dev->mc, dev->addr_len);
+        __hw_addr_unsync(&local->mc_list, &sdata->dev->mc,
+                         sdata->dev->addr_len);
         spin_unlock_bh(&local->filter_lock);
-        netif_addr_unlock_bh(dev);
+        netif_addr_unlock_bh(sdata->dev);
 
         ieee80211_configure_filter(local);
 
@@ -432,7 +454,8 @@ static int ieee80211_stop(struct net_device *dev)
                 WARN_ON(!list_empty(&sdata->u.ap.vlans));
         }
 
-        local->open_count--;
+        if (going_down)
+                local->open_count--;
 
         switch (sdata->vif.type) {
         case NL80211_IFTYPE_AP_VLAN:
@@ -504,7 +527,8 @@ static int ieee80211_stop(struct net_device *dev)
                  */
                 ieee80211_free_keys(sdata);
 
-                drv_remove_interface(local, &sdata->vif);
+                if (going_down)
+                        drv_remove_interface(local, &sdata->vif);
         }
 
         sdata->bss = NULL;
@@ -540,6 +564,13 @@ static int ieee80211_stop(struct net_device *dev)
                 }
         }
         spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
+}
+
+static int ieee80211_stop(struct net_device *dev)
+{
+        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+
+        ieee80211_do_stop(sdata, true);
 
         return 0;
 }
@@ -857,9 +888,72 @@ static void ieee80211_setup_sdata(struct ieee80211_sub_if_data *sdata,
         ieee80211_debugfs_add_netdev(sdata);
 }
 
+static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
+                                           enum nl80211_iftype type)
+{
+        struct ieee80211_local *local = sdata->local;
+        int ret, err;
+
+        ASSERT_RTNL();
+
+        if (!local->ops->change_interface)
+                return -EBUSY;
+
+        switch (sdata->vif.type) {
+        case NL80211_IFTYPE_AP:
+        case NL80211_IFTYPE_STATION:
+        case NL80211_IFTYPE_ADHOC:
+                /*
+                 * Could maybe also all others here?
+                 * Just not sure how that interacts
+                 * with the RX/config path e.g. for
+                 * mesh.
+                 */
+                break;
+        default:
+                return -EBUSY;
+        }
+
+        switch (type) {
+        case NL80211_IFTYPE_AP:
+        case NL80211_IFTYPE_STATION:
+        case NL80211_IFTYPE_ADHOC:
+                /*
+                 * Could probably support everything
+                 * but WDS here (WDS do_open can fail
+                 * under memory pressure, which this
+                 * code isn't prepared to handle).
+                 */
+                break;
+        default:
+                return -EBUSY;
+        }
+
+        ret = ieee80211_check_concurrent_iface(sdata, type);
+        if (ret)
+                return ret;
+
+        ieee80211_do_stop(sdata, false);
+
+        ieee80211_teardown_sdata(sdata->dev);
+
+        ret = drv_change_interface(local, sdata, type);
+        if (ret)
+                type = sdata->vif.type;
+
+        ieee80211_setup_sdata(sdata, type);
+
+        err = ieee80211_do_open(sdata->dev, false);
+        WARN(err, "type change: do_open returned %d", err);
+
+        return ret;
+}
+
 int ieee80211_if_change_type(struct ieee80211_sub_if_data *sdata,
                              enum nl80211_iftype type)
 {
+        int ret;
+
         ASSERT_RTNL();
 
         if (type == sdata->vif.type)
@@ -870,18 +964,15 @@ int ieee80211_if_change_type(struct ieee80211_sub_if_data *sdata,
             type == NL80211_IFTYPE_ADHOC)
                 return -EOPNOTSUPP;
 
-        /*
-         * We could, here, on changes between IBSS/STA/MESH modes,
-         * invoke an MLME function instead that disassociates etc.
-         * and goes into the requested mode.
-         */
-
-        if (ieee80211_sdata_running(sdata))
-                return -EBUSY;
-
-        /* Purge and reset type-dependent state. */
-        ieee80211_teardown_sdata(sdata->dev);
-        ieee80211_setup_sdata(sdata, type);
+        if (ieee80211_sdata_running(sdata)) {
+                ret = ieee80211_runtime_change_iftype(sdata, type);
+                if (ret)
+                        return ret;
+        } else {
+                /* Purge and reset type-dependent state. */
+                ieee80211_teardown_sdata(sdata->dev);
+                ieee80211_setup_sdata(sdata, type);
+        }
 
         /* reset some values that shouldn't be kept across type changes */
         sdata->vif.bss_conf.basic_rates =