mac80211: Optimize scans on current operating channel.

This should decrease un-necessary flushes, on/off channel work,
and channel changes in cases where the only scanned channel is
the current operating channel.

* Removes SCAN_OFF_CHANNEL flag, uses SDATA_STATE_OFFCHANNEL
  and is-scanning flags instead.

* Add helper method to determine if we are currently configured
  for the operating channel.

* Do no blindly go off/on channel in work.c  Instead, only call
  appropriate on/off code when we really need to change channels.
  Always enable offchannel-ps mode when starting work,
  and disable it when we are done.

* Consolidate ieee80211_offchannel_stop_station and
  ieee80211_offchannel_stop_beaconing, call it
  ieee80211_offchannel_stop_vifs instead.

* Accept non-beacon frames when scanning on operating channel.

* Scan state machine optimized to minimize on/off channel
  transitions.  Also, when going on-channel, go ahead and
  re-enable beaconing.  We're going to be there for 200ms,
  so seems like some useful beaconing could happen.
  Always enable offchannel-ps mode when starting software
  scan, and disable it when we are done.

* Grab local->mtx earlier in __ieee80211_scan_completed_finish
  so that we are protected when calling hw_config(), etc.

* Pass probe-responses up the stack if scanning on local
  channel, so that mlme can take a look.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 37 insertions, 31 deletions

diff --git a/net/mac80211/offchannel.c b/net/mac80211/offchannel.c
index b4e52676f3fb..13427b194ced 100644
--- a/net/mac80211/offchannel.c
+++ b/net/mac80211/offchannel.c
@@ -17,10 +17,14 @@
 #include "driver-trace.h"
 
 /*
- * inform AP that we will go to sleep so that it will buffer the frames
- * while we scan
+ * Tell our hardware to disable PS.
+ * Optionally inform AP that we will go to sleep so that it will buffer
+ * the frames while we are doing off-channel work.  This is optional
+ * because we *may* be doing work on-operating channel, and want our
+ * hardware unconditionally awake, but still let the AP send us normal frames.
  */
-static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata)
+static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata,
+                                           bool tell_ap)
 {
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
@@ -41,8 +45,8 @@ static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata)
                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
         }
 
-        if (!(local->offchannel_ps_enabled) ||
-            !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
+        if (tell_ap && (!local->offchannel_ps_enabled ||
+                        !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)))
                 /*
                  * If power save was enabled, no need to send a nullfunc
                  * frame because AP knows that we are sleeping. But if the
@@ -77,6 +81,9 @@ static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
                  * we are sleeping, let's just enable power save mode in
                  * hardware.
                  */
+                /* TODO:  Only set hardware if CONF_PS changed?
+                 * TODO:  Should we set offchannel_ps_enabled to false?
+                 */
                 local->hw.conf.flags |= IEEE80211_CONF_PS;
                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
         } else if (local->hw.conf.dynamic_ps_timeout > 0) {
@@ -95,63 +102,61 @@ static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
         ieee80211_sta_reset_conn_monitor(sdata);
 }
 
-void ieee80211_offchannel_stop_beaconing(struct ieee80211_local *local)
+void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local,
+                                    bool offchannel_ps_enable)
 {
         struct ieee80211_sub_if_data *sdata;
 
+        /*
+         * notify the AP about us leaving the channel and stop all
+         * STA interfaces.
+         */
         mutex_lock(&local->iflist_mtx);
         list_for_each_entry(sdata, &local->interfaces, list) {
                 if (!ieee80211_sdata_running(sdata))
                         continue;
 
-                /* disable beaconing */
+                if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
+                        set_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);
+
+                /* Check to see if we should disable beaconing. */
                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
                         ieee80211_bss_info_change_notify(
                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 
-                /*
-                 * only handle non-STA interfaces here, STA interfaces
-                 * are handled in ieee80211_offchannel_stop_station(),
-                 * e.g., from the background scan state machine.
-                 *
-                 * In addition, do not stop monitor interface to allow it to be
-                 * used from user space controlled off-channel operations.
-                 */
-                if (sdata->vif.type != NL80211_IFTYPE_STATION &&
-                    sdata->vif.type != NL80211_IFTYPE_MONITOR) {
-                        set_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);
+                if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
                         netif_tx_stop_all_queues(sdata->dev);
+                        if (offchannel_ps_enable &&
+                            (sdata->vif.type == NL80211_IFTYPE_STATION) &&
+                            sdata->u.mgd.associated)
+                                ieee80211_offchannel_ps_enable(sdata, true);
                 }
         }
         mutex_unlock(&local->iflist_mtx);
 }
 
-void ieee80211_offchannel_stop_station(struct ieee80211_local *local)
+void ieee80211_offchannel_enable_all_ps(struct ieee80211_local *local,
+                                        bool tell_ap)
 {
         struct ieee80211_sub_if_data *sdata;
 
-        /*
-         * notify the AP about us leaving the channel and stop all STA interfaces
-         */
         mutex_lock(&local->iflist_mtx);
         list_for_each_entry(sdata, &local->interfaces, list) {
                 if (!ieee80211_sdata_running(sdata))
                         continue;
 
-                if (sdata->vif.type == NL80211_IFTYPE_STATION) {
-                        set_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);
-                        netif_tx_stop_all_queues(sdata->dev);
-                        if (sdata->u.mgd.associated)
-                                ieee80211_offchannel_ps_enable(sdata);
-                }
+                if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+                    sdata->u.mgd.associated)
+                        ieee80211_offchannel_ps_enable(sdata, tell_ap);
         }
         mutex_unlock(&local->iflist_mtx);
 }
 
 void ieee80211_offchannel_return(struct ieee80211_local *local,
-                                 bool enable_beaconing)
+                                 bool enable_beaconing,
+                                 bool offchannel_ps_disable)
 {
         struct ieee80211_sub_if_data *sdata;
 
@@ -161,7 +166,8 @@ void ieee80211_offchannel_return(struct ieee80211_local *local,
                         continue;
 
                 /* Tell AP we're back */
-                if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+                if (offchannel_ps_disable &&
+                    sdata->vif.type == NL80211_IFTYPE_STATION) {
                         if (sdata->u.mgd.associated)
                                 ieee80211_offchannel_ps_disable(sdata);
                 }
@@ -181,7 +187,7 @@ void ieee80211_offchannel_return(struct ieee80211_local *local,
                         netif_tx_wake_all_queues(sdata->dev);
                 }
 
-                /* re-enable beaconing */
+                /* Check to see if we should re-enable beaconing */
                 if (enable_beaconing &&
                     (sdata->vif.type == NL80211_IFTYPE_AP ||
                      sdata->vif.type == NL80211_IFTYPE_ADHOC ||