mac80211: wait for beacon before enabling powersave
[linux-2.6.git] / net / mac80211 / scan.c
index c6b275b..bc061f6 100644 (file)
  * published by the Free Software Foundation.
  */
 
-/* TODO:
- * figure out how to avoid that the "current BSS" expires
- * clean up IBSS code (in MLME), see why it adds a BSS to the list
- * use cfg80211's BSS handling (depends on IBSS TODO above)
- * order BSS list by RSSI(?) ("quality of AP")
- * scan result table filtering (by capability (privacy, IBSS/BSS, WPA/RSN IE,
- *    SSID)
- */
-
-#include <linux/wireless.h>
 #include <linux/if_arp.h>
 #include <linux/rtnetlink.h>
 #include <net/mac80211.h>
-#include <net/iw_handler.h>
 
 #include "ieee80211_i.h"
+#include "driver-ops.h"
 #include "mesh.h"
 
 #define IEEE80211_PROBE_DELAY (HZ / 33)
 #define IEEE80211_CHANNEL_TIME (HZ / 33)
-#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)
-
-void ieee80211_rx_bss_list_init(struct ieee80211_local *local)
-{
-       spin_lock_init(&local->bss_lock);
-       INIT_LIST_HEAD(&local->bss_list);
-}
-
-void ieee80211_rx_bss_list_deinit(struct ieee80211_local *local)
-{
-       struct ieee80211_bss *bss, *tmp;
-
-       list_for_each_entry_safe(bss, tmp, &local->bss_list, list)
-               ieee80211_rx_bss_put(local, bss);
-}
+#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
 
 struct ieee80211_bss *
 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
                     u8 *ssid, u8 ssid_len)
 {
-       struct ieee80211_bss *bss;
-
-       spin_lock_bh(&local->bss_lock);
-       bss = local->bss_hash[STA_HASH(bssid)];
-       while (bss) {
-               if (!bss_mesh_cfg(bss) &&
-                   !memcmp(bss->bssid, bssid, ETH_ALEN) &&
-                   bss->freq == freq &&
-                   bss->ssid_len == ssid_len &&
-                   (ssid_len == 0 || !memcmp(bss->ssid, ssid, ssid_len))) {
-                       atomic_inc(&bss->users);
-                       break;
-               }
-               bss = bss->hnext;
-       }
-       spin_unlock_bh(&local->bss_lock);
-       return bss;
-}
-
-/* Caller must hold local->bss_lock */
-static void __ieee80211_rx_bss_hash_add(struct ieee80211_local *local,
-                                       struct ieee80211_bss *bss)
-{
-       u8 hash_idx;
-
-       if (bss_mesh_cfg(bss))
-               hash_idx = mesh_id_hash(bss_mesh_id(bss),
-                                       bss_mesh_id_len(bss));
-       else
-               hash_idx = STA_HASH(bss->bssid);
-
-       bss->hnext = local->bss_hash[hash_idx];
-       local->bss_hash[hash_idx] = bss;
-}
-
-/* Caller must hold local->bss_lock */
-static void __ieee80211_rx_bss_hash_del(struct ieee80211_local *local,
-                                       struct ieee80211_bss *bss)
-{
-       struct ieee80211_bss *b, *prev = NULL;
-       b = local->bss_hash[STA_HASH(bss->bssid)];
-       while (b) {
-               if (b == bss) {
-                       if (!prev)
-                               local->bss_hash[STA_HASH(bss->bssid)] =
-                                       bss->hnext;
-                       else
-                               prev->hnext = bss->hnext;
-                       break;
-               }
-               prev = b;
-               b = b->hnext;
-       }
-}
-
-struct ieee80211_bss *
-ieee80211_rx_bss_add(struct ieee80211_local *local, u8 *bssid, int freq,
-                    u8 *ssid, u8 ssid_len)
-{
-       struct ieee80211_bss *bss;
+       struct cfg80211_bss *cbss;
 
-       bss = kzalloc(sizeof(*bss), GFP_ATOMIC);
-       if (!bss)
+       cbss = cfg80211_get_bss(local->hw.wiphy,
+                               ieee80211_get_channel(local->hw.wiphy, freq),
+                               bssid, ssid, ssid_len, 0, 0);
+       if (!cbss)
                return NULL;
-       atomic_set(&bss->users, 2);
-       memcpy(bss->bssid, bssid, ETH_ALEN);
-       bss->freq = freq;
-       if (ssid && ssid_len <= IEEE80211_MAX_SSID_LEN) {
-               memcpy(bss->ssid, ssid, ssid_len);
-               bss->ssid_len = ssid_len;
-       }
-
-       spin_lock_bh(&local->bss_lock);
-       /* TODO: order by RSSI? */
-       list_add_tail(&bss->list, &local->bss_list);
-       __ieee80211_rx_bss_hash_add(local, bss);
-       spin_unlock_bh(&local->bss_lock);
-       return bss;
+       return (void *)cbss->priv;
 }
 
-#ifdef CONFIG_MAC80211_MESH
-static struct ieee80211_bss *
-ieee80211_rx_mesh_bss_get(struct ieee80211_local *local, u8 *mesh_id, int mesh_id_len,
-                         u8 *mesh_cfg, int freq)
+static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
 {
-       struct ieee80211_bss *bss;
+       struct ieee80211_bss *bss = (void *)cbss->priv;
 
-       spin_lock_bh(&local->bss_lock);
-       bss = local->bss_hash[mesh_id_hash(mesh_id, mesh_id_len)];
-       while (bss) {
-               if (bss_mesh_cfg(bss) &&
-                   !memcmp(bss_mesh_cfg(bss), mesh_cfg, MESH_CFG_CMP_LEN) &&
-                   bss->freq == freq &&
-                   mesh_id_len == bss->mesh_id_len &&
-                   (mesh_id_len == 0 || !memcmp(bss->mesh_id, mesh_id,
-                                                mesh_id_len))) {
-                       atomic_inc(&bss->users);
-                       break;
-               }
-               bss = bss->hnext;
-       }
-       spin_unlock_bh(&local->bss_lock);
-       return bss;
-}
-
-static struct ieee80211_bss *
-ieee80211_rx_mesh_bss_add(struct ieee80211_local *local, u8 *mesh_id, int mesh_id_len,
-                         u8 *mesh_cfg, int mesh_config_len, int freq)
-{
-       struct ieee80211_bss *bss;
-
-       if (mesh_config_len != IEEE80211_MESH_CONFIG_LEN)
-               return NULL;
-
-       bss = kzalloc(sizeof(*bss), GFP_ATOMIC);
-       if (!bss)
-               return NULL;
-
-       bss->mesh_cfg = kmalloc(MESH_CFG_CMP_LEN, GFP_ATOMIC);
-       if (!bss->mesh_cfg) {
-               kfree(bss);
-               return NULL;
-       }
-
-       if (mesh_id_len && mesh_id_len <= IEEE80211_MAX_MESH_ID_LEN) {
-               bss->mesh_id = kmalloc(mesh_id_len, GFP_ATOMIC);
-               if (!bss->mesh_id) {
-                       kfree(bss->mesh_cfg);
-                       kfree(bss);
-                       return NULL;
-               }
-               memcpy(bss->mesh_id, mesh_id, mesh_id_len);
-       }
-
-       atomic_set(&bss->users, 2);
-       memcpy(bss->mesh_cfg, mesh_cfg, MESH_CFG_CMP_LEN);
-       bss->mesh_id_len = mesh_id_len;
-       bss->freq = freq;
-       spin_lock_bh(&local->bss_lock);
-       /* TODO: order by RSSI? */
-       list_add_tail(&bss->list, &local->bss_list);
-       __ieee80211_rx_bss_hash_add(local, bss);
-       spin_unlock_bh(&local->bss_lock);
-       return bss;
-}
-#endif
-
-static void ieee80211_rx_bss_free(struct ieee80211_bss *bss)
-{
-       kfree(bss->ies);
        kfree(bss_mesh_id(bss));
        kfree(bss_mesh_cfg(bss));
-       kfree(bss);
 }
 
 void ieee80211_rx_bss_put(struct ieee80211_local *local,
                          struct ieee80211_bss *bss)
 {
-       local_bh_disable();
-       if (!atomic_dec_and_lock(&bss->users, &local->bss_lock)) {
-               local_bh_enable();
+       if (!bss)
                return;
-       }
+       cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
+}
 
-       __ieee80211_rx_bss_hash_del(local, bss);
-       list_del(&bss->list);
-       spin_unlock_bh(&local->bss_lock);
-       ieee80211_rx_bss_free(bss);
+static bool is_uapsd_supported(struct ieee802_11_elems *elems)
+{
+       u8 qos_info;
+
+       if (elems->wmm_info && elems->wmm_info_len == 7
+           && elems->wmm_info[5] == 1)
+               qos_info = elems->wmm_info[6];
+       else if (elems->wmm_param && elems->wmm_param_len == 24
+                && elems->wmm_param[5] == 1)
+               qos_info = elems->wmm_param[6];
+       else
+               /* no valid wmm information or parameter element found */
+               return false;
+
+       return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
 }
 
 struct ieee80211_bss *
@@ -231,52 +80,24 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
                          struct ieee80211_channel *channel,
                          bool beacon)
 {
+       struct cfg80211_bss *cbss;
        struct ieee80211_bss *bss;
-       int clen, freq = channel->center_freq;
-       enum cfg80211_signal_type sigtype = CFG80211_SIGNAL_TYPE_NONE;
+       int clen;
        s32 signal = 0;
 
-       if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
-               sigtype = CFG80211_SIGNAL_TYPE_MBM;
+       if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
                signal = rx_status->signal * 100;
-       } else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC) {
-               sigtype = CFG80211_SIGNAL_TYPE_UNSPEC;
+       else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
                signal = (rx_status->signal * 100) / local->hw.max_signal;
-       }
 
-       cfg80211_put_bss(
-               cfg80211_inform_bss_frame(local->hw.wiphy, channel,
-                                         mgmt, len, signal, sigtype,
-                                         GFP_ATOMIC));
+       cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
+                                        mgmt, len, signal, GFP_ATOMIC);
 
-#ifdef CONFIG_MAC80211_MESH
-       if (elems->mesh_config)
-               bss = ieee80211_rx_mesh_bss_get(local, elems->mesh_id,
-                               elems->mesh_id_len, elems->mesh_config, freq);
-       else
-#endif
-               bss = ieee80211_rx_bss_get(local, mgmt->bssid, freq,
-                                          elems->ssid, elems->ssid_len);
-       if (!bss) {
-#ifdef CONFIG_MAC80211_MESH
-               if (elems->mesh_config)
-                       bss = ieee80211_rx_mesh_bss_add(local, elems->mesh_id,
-                               elems->mesh_id_len, elems->mesh_config,
-                               elems->mesh_config_len, freq);
-               else
-#endif
-                       bss = ieee80211_rx_bss_add(local, mgmt->bssid, freq,
-                                                 elems->ssid, elems->ssid_len);
-               if (!bss)
-                       return NULL;
-       } else {
-#if 0
-               /* TODO: order by RSSI? */
-               spin_lock_bh(&local->bss_lock);
-               list_move_tail(&bss->list, &local->bss_list);
-               spin_unlock_bh(&local->bss_lock);
-#endif
-       }
+       if (!cbss)
+               return NULL;
+
+       cbss->free_priv = ieee80211_rx_bss_free;
+       bss = (void *)cbss->priv;
 
        /* save the ERP value so that it is available at association time */
        if (elems->erp_info && elems->erp_info_len >= 1) {
@@ -284,19 +105,12 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
                bss->has_erp_value = 1;
        }
 
-       bss->beacon_int = le16_to_cpu(mgmt->u.beacon.beacon_int);
-       bss->capability = le16_to_cpu(mgmt->u.beacon.capab_info);
-
        if (elems->tim) {
                struct ieee80211_tim_ie *tim_ie =
                        (struct ieee80211_tim_ie *)elems->tim;
                bss->dtim_period = tim_ie->dtim_period;
        }
 
-       /* set default value for buggy APs */
-       if (!elems->tim || bss->dtim_period == 0)
-               bss->dtim_period = 1;
-
        bss->supp_rates_len = 0;
        if (elems->supp_rates) {
                clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
@@ -315,54 +129,19 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
                bss->supp_rates_len += clen;
        }
 
-       bss->band = rx_status->band;
-
-       bss->timestamp = le64_to_cpu(mgmt->u.beacon.timestamp);
-       bss->last_update = jiffies;
-       bss->signal = rx_status->signal;
-       bss->noise = rx_status->noise;
-       bss->qual = rx_status->qual;
        bss->wmm_used = elems->wmm_param || elems->wmm_info;
+       bss->uapsd_supported = is_uapsd_supported(elems);
 
        if (!beacon)
                bss->last_probe_resp = jiffies;
 
-       /*
-        * For probe responses, or if we don't have any information yet,
-        * use the IEs from the beacon.
-        */
-       if (!bss->ies || !beacon) {
-               if (bss->ies == NULL || bss->ies_len < elems->total_len) {
-                       kfree(bss->ies);
-                       bss->ies = kmalloc(elems->total_len, GFP_ATOMIC);
-               }
-               if (bss->ies) {
-                       memcpy(bss->ies, elems->ie_start, elems->total_len);
-                       bss->ies_len = elems->total_len;
-               } else
-                       bss->ies_len = 0;
-       }
-
        return bss;
 }
 
-void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
-                            int freq, u8 *ssid, u8 ssid_len)
-{
-       struct ieee80211_bss *bss;
-       struct ieee80211_local *local = sdata->local;
-
-       bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
-       if (bss) {
-               atomic_dec(&bss->users);
-               ieee80211_rx_bss_put(local, bss);
-       }
-}
-
 ieee80211_rx_result
-ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
-                 struct ieee80211_rx_status *rx_status)
+ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 {
+       struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
        struct ieee80211_mgmt *mgmt;
        struct ieee80211_bss *bss;
        u8 *elements;
@@ -388,7 +167,7 @@ ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
        presp = ieee80211_is_probe_resp(fc);
        if (presp) {
                /* ignore ProbeResp to foreign address */
-               if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
+               if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
                        return RX_DROP_MONITOR;
 
                presp = true;
@@ -428,304 +207,489 @@ ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
        return RX_QUEUED;
 }
 
-void ieee80211_send_nullfunc(struct ieee80211_local *local,
-                                   struct ieee80211_sub_if_data *sdata,
-                                   int powersave)
+/* return false if no more work */
+static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 {
-       struct sk_buff *skb;
-       struct ieee80211_hdr *nullfunc;
-       __le16 fc;
+       struct cfg80211_scan_request *req = local->scan_req;
+       enum ieee80211_band band;
+       int i, ielen, n_chans;
+
+       do {
+               if (local->hw_scan_band == IEEE80211_NUM_BANDS)
+                       return false;
+
+               band = local->hw_scan_band;
+               n_chans = 0;
+               for (i = 0; i < req->n_channels; i++) {
+                       if (req->channels[i]->band == band) {
+                               local->hw_scan_req->channels[n_chans] =
+                                                       req->channels[i];
+                               n_chans++;
+                       }
+               }
 
-       skb = dev_alloc_skb(local->hw.extra_tx_headroom + 24);
-       if (!skb) {
-               printk(KERN_DEBUG "%s: failed to allocate buffer for nullfunc "
-                      "frame\n", sdata->dev->name);
-               return;
-       }
-       skb_reserve(skb, local->hw.extra_tx_headroom);
-
-       nullfunc = (struct ieee80211_hdr *) skb_put(skb, 24);
-       memset(nullfunc, 0, 24);
-       fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC |
-                        IEEE80211_FCTL_TODS);
-       if (powersave)
-               fc |= cpu_to_le16(IEEE80211_FCTL_PM);
-       nullfunc->frame_control = fc;
-       memcpy(nullfunc->addr1, sdata->u.sta.bssid, ETH_ALEN);
-       memcpy(nullfunc->addr2, sdata->dev->dev_addr, ETH_ALEN);
-       memcpy(nullfunc->addr3, sdata->u.sta.bssid, ETH_ALEN);
-
-       ieee80211_tx_skb(sdata, skb, 0);
+               local->hw_scan_band++;
+       } while (!n_chans);
+
+       local->hw_scan_req->n_channels = n_chans;
+
+       ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
+                                        req->ie, req->ie_len, band);
+       local->hw_scan_req->ie_len = ielen;
+
+       return true;
 }
 
 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 {
        struct ieee80211_local *local = hw_to_local(hw);
-       struct ieee80211_sub_if_data *sdata;
+       bool was_hw_scan;
+
+       mutex_lock(&local->scan_mtx);
 
-       if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
+       /*
+        * It's ok to abort a not-yet-running scan (that
+        * we have one at all will be verified by checking
+        * local->scan_req next), but not to complete it
+        * successfully.
+        */
+       if (WARN_ON(!local->scanning && !aborted))
+               aborted = true;
+
+       if (WARN_ON(!local->scan_req)) {
+               mutex_unlock(&local->scan_mtx);
                return;
+       }
 
-       if (WARN_ON(!local->scan_req))
+       was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
+       if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
+               ieee80211_queue_delayed_work(&local->hw,
+                                            &local->scan_work, 0);
+               mutex_unlock(&local->scan_mtx);
                return;
+       }
 
-       if (local->scan_req != &local->int_scan_req)
+       kfree(local->hw_scan_req);
+       local->hw_scan_req = NULL;
+
+       if (local->scan_req != local->int_scan_req)
                cfg80211_scan_done(local->scan_req, aborted);
        local->scan_req = NULL;
+       local->scan_sdata = NULL;
 
-       local->last_scan_completed = jiffies;
+       local->scanning = 0;
+       local->scan_channel = NULL;
 
-       if (local->hw_scanning) {
-               local->hw_scanning = false;
-               /*
-                * Somebody might have requested channel change during scan
-                * that we won't have acted upon, try now. ieee80211_hw_config
-                * will set the flag based on actual changes.
-                */
-               ieee80211_hw_config(local, 0);
-               goto done;
-       }
+       /* we only have to protect scan_req and hw/sw scan */
+       mutex_unlock(&local->scan_mtx);
 
-       local->sw_scanning = false;
        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+       if (was_hw_scan)
+               goto done;
 
-       netif_tx_lock_bh(local->mdev);
-       netif_addr_lock(local->mdev);
-       local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
-       local->ops->configure_filter(local_to_hw(local),
-                                    FIF_BCN_PRBRESP_PROMISC,
-                                    &local->filter_flags,
-                                    local->mdev->mc_count,
-                                    local->mdev->mc_list);
+       ieee80211_configure_filter(local);
 
-       netif_addr_unlock(local->mdev);
-       netif_tx_unlock_bh(local->mdev);
+       drv_sw_scan_complete(local);
 
-       mutex_lock(&local->iflist_mtx);
-       list_for_each_entry(sdata, &local->interfaces, list) {
-               if (!netif_running(sdata->dev))
-                       continue;
-
-               /* Tell AP we're back */
-               if (sdata->vif.type == NL80211_IFTYPE_STATION) {
-                       if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
-                               ieee80211_send_nullfunc(local, sdata, 0);
-                               netif_tx_wake_all_queues(sdata->dev);
-                       }
-               } else
-                       netif_tx_wake_all_queues(sdata->dev);
-
-               /* re-enable beaconing */
-               if (sdata->vif.type == NL80211_IFTYPE_AP ||
-                   sdata->vif.type == NL80211_IFTYPE_ADHOC ||
-                   sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
-                       ieee80211_if_config(sdata,
-                                           IEEE80211_IFCC_BEACON_ENABLED);
-       }
-       mutex_unlock(&local->iflist_mtx);
+       ieee80211_offchannel_return(local, true);
 
  done:
+       ieee80211_recalc_idle(local);
        ieee80211_mlme_notify_scan_completed(local);
+       ieee80211_ibss_notify_scan_completed(local);
        ieee80211_mesh_notify_scan_completed(local);
+       ieee80211_queue_work(&local->hw, &local->work_work);
 }
 EXPORT_SYMBOL(ieee80211_scan_completed);
 
-void ieee80211_scan_work(struct work_struct *work)
+static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 {
-       struct ieee80211_local *local =
-               container_of(work, struct ieee80211_local, scan_work.work);
-       struct ieee80211_sub_if_data *sdata = local->scan_sdata;
-       struct ieee80211_channel *chan;
-       int skip, i;
-       unsigned long next_delay = 0;
-
        /*
-        * Avoid re-scheduling when the sdata is going away.
+        * Hardware/driver doesn't support hw_scan, so use software
+        * scanning instead. First send a nullfunc frame with power save
+        * bit on so that AP will buffer the frames for us while we are not
+        * listening, then send probe requests to each channel and wait for
+        * the responses. After all channels are scanned, tune back to the
+        * original channel and send a nullfunc frame with power save bit
+        * off to trigger the AP to send us all the buffered frames.
+        *
+        * Note that while local->sw_scanning is true everything else but
+        * nullfunc frames and probe requests will be dropped in
+        * ieee80211_tx_h_check_assoc().
         */
-       if (!netif_running(sdata->dev))
-               return;
+       drv_sw_scan_start(local);
 
-       switch (local->scan_state) {
-       case SCAN_SET_CHANNEL:
-               /* if no more bands/channels left, complete scan */
-               if (local->scan_channel_idx >= local->scan_req->n_channels) {
-                       ieee80211_scan_completed(local_to_hw(local), false);
-                       return;
-               }
-               skip = 0;
-               chan = local->scan_req->channels[local->scan_channel_idx];
-
-               if (chan->flags & IEEE80211_CHAN_DISABLED ||
-                   (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
-                    chan->flags & IEEE80211_CHAN_NO_IBSS))
-                       skip = 1;
-
-               if (!skip) {
-                       local->scan_channel = chan;
-                       if (ieee80211_hw_config(local,
-                                               IEEE80211_CONF_CHANGE_CHANNEL))
-                               skip = 1;
-               }
+       ieee80211_offchannel_stop_beaconing(local);
 
-               /* advance state machine to next channel/band */
-               local->scan_channel_idx++;
+       local->next_scan_state = SCAN_DECISION;
+       local->scan_channel_idx = 0;
 
-               if (skip)
-                       break;
+       drv_flush(local, false);
 
-               next_delay = IEEE80211_PROBE_DELAY +
-                            usecs_to_jiffies(local->hw.channel_change_time);
-               local->scan_state = SCAN_SEND_PROBE;
-               break;
-       case SCAN_SEND_PROBE:
-               next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
-               local->scan_state = SCAN_SET_CHANNEL;
+       ieee80211_configure_filter(local);
 
-               if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
-                   !local->scan_req->n_ssids)
-                       break;
-               for (i = 0; i < local->scan_req->n_ssids; i++)
-                       ieee80211_send_probe_req(
-                               sdata, NULL,
-                               local->scan_req->ssids[i].ssid,
-                               local->scan_req->ssids[i].ssid_len);
-               next_delay = IEEE80211_CHANNEL_TIME;
-               break;
-       }
+       ieee80211_queue_delayed_work(&local->hw,
+                                    &local->scan_work,
+                                    IEEE80211_CHANNEL_TIME);
 
-       queue_delayed_work(local->hw.workqueue, &local->scan_work,
-                          next_delay);
+       return 0;
 }
 
 
-int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
-                        struct cfg80211_scan_request *req)
+static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
+                                 struct cfg80211_scan_request *req)
 {
-       struct ieee80211_local *local = scan_sdata->local;
-       struct ieee80211_sub_if_data *sdata;
-
-       if (!req)
-               return -EINVAL;
+       struct ieee80211_local *local = sdata->local;
+       int rc;
 
-       if (local->scan_req && local->scan_req != req)
+       if (local->scan_req)
                return -EBUSY;
 
+       if (local->ops->hw_scan) {
+               u8 *ies;
+
+               local->hw_scan_req = kmalloc(
+                               sizeof(*local->hw_scan_req) +
+                               req->n_channels * sizeof(req->channels[0]) +
+                               2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
+                               req->ie_len, GFP_KERNEL);
+               if (!local->hw_scan_req)
+                       return -ENOMEM;
+
+               local->hw_scan_req->ssids = req->ssids;
+               local->hw_scan_req->n_ssids = req->n_ssids;
+               ies = (u8 *)local->hw_scan_req +
+                       sizeof(*local->hw_scan_req) +
+                       req->n_channels * sizeof(req->channels[0]);
+               local->hw_scan_req->ie = ies;
+
+               local->hw_scan_band = 0;
+       }
+
        local->scan_req = req;
+       local->scan_sdata = sdata;
 
-       /* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
-        * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
-        * BSSID: MACAddress
-        * SSID
-        * ScanType: ACTIVE, PASSIVE
-        * ProbeDelay: delay (in microseconds) to be used prior to transmitting
-        *    a Probe frame during active scanning
-        * ChannelList
-        * MinChannelTime (>= ProbeDelay), in TU
-        * MaxChannelTime: (>= MinChannelTime), in TU
-        */
+       if (!list_empty(&local->work_list)) {
+               /* wait for the work to finish/time out */
+               return 0;
+       }
 
-        /* MLME-SCAN.confirm
-         * BSSDescriptionSet
-         * ResultCode: SUCCESS, INVALID_PARAMETERS
+       if (local->ops->hw_scan)
+               __set_bit(SCAN_HW_SCANNING, &local->scanning);
+       else
+               __set_bit(SCAN_SW_SCANNING, &local->scanning);
+       /*
+        * Kicking off the scan need not be protected,
+        * only the scan variable stuff, since now
+        * local->scan_req is assigned and other callers
+        * will abort their scan attempts.
+        *
+        * This avoids getting a scan_mtx -> iflist_mtx
+        * dependency, so that the scan completed calls
+        * have more locking freedom.
         */
 
-       if (local->sw_scanning || local->hw_scanning) {
-               if (local->scan_sdata == scan_sdata)
-                       return 0;
-               return -EBUSY;
-       }
+       ieee80211_recalc_idle(local);
+       mutex_unlock(&local->scan_mtx);
 
        if (local->ops->hw_scan) {
-               int rc;
+               WARN_ON(!ieee80211_prep_hw_scan(local));
+               rc = drv_hw_scan(local, local->hw_scan_req);
+       } else
+               rc = ieee80211_start_sw_scan(local);
 
-               local->hw_scanning = true;
-               rc = local->ops->hw_scan(local_to_hw(local), req);
-               if (rc) {
-                       local->hw_scanning = false;
-                       return rc;
-               }
-               local->scan_sdata = scan_sdata;
-               return 0;
+       mutex_lock(&local->scan_mtx);
+
+       if (rc) {
+               kfree(local->hw_scan_req);
+               local->hw_scan_req = NULL;
+               local->scanning = 0;
+
+               ieee80211_recalc_idle(local);
+
+               local->scan_req = NULL;
+               local->scan_sdata = NULL;
        }
 
-       local->sw_scanning = true;
+       return rc;
+}
 
+static int ieee80211_scan_state_decision(struct ieee80211_local *local,
+                                        unsigned long *next_delay)
+{
+       bool associated = false;
+       struct ieee80211_sub_if_data *sdata;
+
+       /* if no more bands/channels left, complete scan and advance to the idle state */
+       if (local->scan_channel_idx >= local->scan_req->n_channels) {
+               ieee80211_scan_completed(&local->hw, false);
+               return 1;
+       }
+
+       /* check if at least one STA interface is associated */
        mutex_lock(&local->iflist_mtx);
        list_for_each_entry(sdata, &local->interfaces, list) {
-               if (!netif_running(sdata->dev))
+               if (!ieee80211_sdata_running(sdata))
                        continue;
 
-               /* disable beaconing */
-               if (sdata->vif.type == NL80211_IFTYPE_AP ||
-                   sdata->vif.type == NL80211_IFTYPE_ADHOC ||
-                   sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
-                       ieee80211_if_config(sdata,
-                                           IEEE80211_IFCC_BEACON_ENABLED);
-
                if (sdata->vif.type == NL80211_IFTYPE_STATION) {
-                       if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
-                               netif_tx_stop_all_queues(sdata->dev);
-                               ieee80211_send_nullfunc(local, sdata, 1);
+                       if (sdata->u.mgd.associated) {
+                               associated = true;
+                               break;
                        }
-               } else
-                       netif_tx_stop_all_queues(sdata->dev);
+               }
        }
        mutex_unlock(&local->iflist_mtx);
 
-       local->scan_state = SCAN_SET_CHANNEL;
-       local->scan_channel_idx = 0;
-       local->scan_sdata = scan_sdata;
-       local->scan_req = req;
+       if (local->scan_channel) {
+               /*
+                * we're currently scanning a different channel, let's
+                * switch back to the operating channel now if at least
+                * one interface is associated. Otherwise just scan the
+                * next channel
+                */
+               if (associated)
+                       local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+               else
+                       local->next_scan_state = SCAN_SET_CHANNEL;
+       } else {
+               /*
+                * we're on the operating channel currently, let's
+                * leave that channel now to scan another one
+                */
+               local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
+       }
 
-       netif_addr_lock_bh(local->mdev);
-       local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
-       local->ops->configure_filter(local_to_hw(local),
-                                    FIF_BCN_PRBRESP_PROMISC,
-                                    &local->filter_flags,
-                                    local->mdev->mc_count,
-                                    local->mdev->mc_list);
-       netif_addr_unlock_bh(local->mdev);
+       *next_delay = 0;
+       return 0;
+}
+
+static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
+                                                   unsigned long *next_delay)
+{
+       ieee80211_offchannel_stop_station(local);
 
-       /* TODO: start scan as soon as all nullfunc frames are ACKed */
-       queue_delayed_work(local->hw.workqueue, &local->scan_work,
-                          IEEE80211_CHANNEL_TIME);
+       __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 
-       return 0;
+       /*
+        * What if the nullfunc frames didn't arrive?
+        */
+       drv_flush(local, false);
+       if (local->ops->flush)
+               *next_delay = 0;
+       else
+               *next_delay = HZ / 10;
+
+       /* advance to the next channel to be scanned */
+       local->next_scan_state = SCAN_SET_CHANNEL;
 }
 
+static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
+                                                   unsigned long *next_delay)
+{
+       /* switch back to the operating channel */
+       local->scan_channel = NULL;
+       ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 
-int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
-                          struct cfg80211_scan_request *req)
+       /*
+        * Only re-enable station mode interface now; beaconing will be
+        * re-enabled once the full scan has been completed.
+        */
+       ieee80211_offchannel_return(local, false);
+
+       __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
+
+       *next_delay = HZ / 5;
+       local->next_scan_state = SCAN_DECISION;
+}
+
+static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
+                                            unsigned long *next_delay)
 {
-       struct ieee80211_local *local = sdata->local;
-       struct ieee80211_if_sta *ifsta;
+       int skip;
+       struct ieee80211_channel *chan;
 
-       if (!req)
-               return -EINVAL;
+       skip = 0;
+       chan = local->scan_req->channels[local->scan_channel_idx];
 
-       if (local->scan_req && local->scan_req != req)
-               return -EBUSY;
+       local->scan_channel = chan;
+       if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
+               skip = 1;
 
-       local->scan_req = req;
+       /* advance state machine to next channel/band */
+       local->scan_channel_idx++;
 
-       if (sdata->vif.type != NL80211_IFTYPE_STATION)
-               return ieee80211_start_scan(sdata, req);
+       if (skip) {
+               /* if we skip this channel return to the decision state */
+               local->next_scan_state = SCAN_DECISION;
+               return;
+       }
 
        /*
-        * STA has a state machine that might need to defer scanning
-        * while it's trying to associate/authenticate, therefore we
-        * queue it up to the state machine in that case.
+        * Probe delay is used to update the NAV, cf. 11.1.3.2.2
+        * (which unfortunately doesn't say _why_ step a) is done,
+        * but it waits for the probe delay or until a frame is
+        * received - and the received frame would update the NAV).
+        * For now, we do not support waiting until a frame is
+        * received.
+        *
+        * In any case, it is not necessary for a passive scan.
         */
+       if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
+           !local->scan_req->n_ssids) {
+               *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
+               local->next_scan_state = SCAN_DECISION;
+               return;
+       }
 
-       if (local->sw_scanning || local->hw_scanning) {
-               if (local->scan_sdata == sdata)
-                       return 0;
-               return -EBUSY;
+       /* active scan, send probes */
+       *next_delay = IEEE80211_PROBE_DELAY;
+       local->next_scan_state = SCAN_SEND_PROBE;
+}
+
+static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
+                                           unsigned long *next_delay)
+{
+       int i;
+       struct ieee80211_sub_if_data *sdata = local->scan_sdata;
+
+       for (i = 0; i < local->scan_req->n_ssids; i++)
+               ieee80211_send_probe_req(
+                       sdata, NULL,
+                       local->scan_req->ssids[i].ssid,
+                       local->scan_req->ssids[i].ssid_len,
+                       local->scan_req->ie, local->scan_req->ie_len);
+
+       /*
+        * After sending probe requests, wait for probe responses
+        * on the channel.
+        */
+       *next_delay = IEEE80211_CHANNEL_TIME;
+       local->next_scan_state = SCAN_DECISION;
+}
+
+void ieee80211_scan_work(struct work_struct *work)
+{
+       struct ieee80211_local *local =
+               container_of(work, struct ieee80211_local, scan_work.work);
+       struct ieee80211_sub_if_data *sdata = local->scan_sdata;
+       unsigned long next_delay = 0;
+
+       mutex_lock(&local->scan_mtx);
+       if (!sdata || !local->scan_req) {
+               mutex_unlock(&local->scan_mtx);
+               return;
        }
 
-       ifsta = &sdata->u.sta;
-       set_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request);
-       queue_work(local->hw.workqueue, &ifsta->work);
+       if (local->hw_scan_req) {
+               int rc = drv_hw_scan(local, local->hw_scan_req);
+               mutex_unlock(&local->scan_mtx);
+               if (rc)
+                       ieee80211_scan_completed(&local->hw, true);
+               return;
+       }
 
-       return 0;
+       if (local->scan_req && !local->scanning) {
+               struct cfg80211_scan_request *req = local->scan_req;
+               int rc;
+
+               local->scan_req = NULL;
+               local->scan_sdata = NULL;
+
+               rc = __ieee80211_start_scan(sdata, req);
+               mutex_unlock(&local->scan_mtx);
+
+               if (rc)
+                       ieee80211_scan_completed(&local->hw, true);
+               return;
+       }
+
+       mutex_unlock(&local->scan_mtx);
+
+       /*
+        * Avoid re-scheduling when the sdata is going away.
+        */
+       if (!ieee80211_sdata_running(sdata)) {
+               ieee80211_scan_completed(&local->hw, true);
+               return;
+       }
+
+       /*
+        * as long as no delay is required advance immediately
+        * without scheduling a new work
+        */
+       do {
+               switch (local->next_scan_state) {
+               case SCAN_DECISION:
+                       if (ieee80211_scan_state_decision(local, &next_delay))
+                               return;
+                       break;
+               case SCAN_SET_CHANNEL:
+                       ieee80211_scan_state_set_channel(local, &next_delay);
+                       break;
+               case SCAN_SEND_PROBE:
+                       ieee80211_scan_state_send_probe(local, &next_delay);
+                       break;
+               case SCAN_LEAVE_OPER_CHANNEL:
+                       ieee80211_scan_state_leave_oper_channel(local, &next_delay);
+                       break;
+               case SCAN_ENTER_OPER_CHANNEL:
+                       ieee80211_scan_state_enter_oper_channel(local, &next_delay);
+                       break;
+               }
+       } while (next_delay == 0);
+
+       ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
+}
+
+int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
+                          struct cfg80211_scan_request *req)
+{
+       int res;
+
+       mutex_lock(&sdata->local->scan_mtx);
+       res = __ieee80211_start_scan(sdata, req);
+       mutex_unlock(&sdata->local->scan_mtx);
+
+       return res;
+}
+
+int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
+                                   const u8 *ssid, u8 ssid_len)
+{
+       struct ieee80211_local *local = sdata->local;
+       int ret = -EBUSY;
+
+       mutex_lock(&local->scan_mtx);
+
+       /* busy scanning */
+       if (local->scan_req)
+               goto unlock;
+
+       memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
+       local->int_scan_req->ssids[0].ssid_len = ssid_len;
+
+       ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
+ unlock:
+       mutex_unlock(&local->scan_mtx);
+       return ret;
+}
+
+void ieee80211_scan_cancel(struct ieee80211_local *local)
+{
+       bool abortscan;
+
+       cancel_delayed_work_sync(&local->scan_work);
+
+       /*
+        * Only call this function when a scan can't be
+        * queued -- mostly at suspend under RTNL.
+        */
+       mutex_lock(&local->scan_mtx);
+       abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
+                   (!local->scanning && local->scan_req);
+       mutex_unlock(&local->scan_mtx);
+
+       if (abortscan)
+               ieee80211_scan_completed(&local->hw, true);
 }