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, 47 insertions, 6 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 09a27449f3fd..c155c0b69426 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -98,6 +98,41 @@ static void ieee80211_reconfig_filter(struct work_struct *work)
         ieee80211_configure_filter(local);
 }
 
+/*
+ * Returns true if we are logically configured to be on
+ * the operating channel AND the hardware-conf is currently
+ * configured on the operating channel.  Compares channel-type
+ * as well.
+ */
+bool ieee80211_cfg_on_oper_channel(struct ieee80211_local *local)
+{
+        struct ieee80211_channel *chan, *scan_chan;
+        enum nl80211_channel_type channel_type;
+
+        /* This logic needs to match logic in ieee80211_hw_config */
+        if (local->scan_channel) {
+                chan = local->scan_channel;
+                channel_type = NL80211_CHAN_NO_HT;
+        } else if (local->tmp_channel) {
+                chan = scan_chan = local->tmp_channel;
+                channel_type = local->tmp_channel_type;
+        } else {
+                chan = local->oper_channel;
+                channel_type = local->_oper_channel_type;
+        }
+
+        if (chan != local->oper_channel ||
+            channel_type != local->_oper_channel_type)
+                return false;
+
+        /* Check current hardware-config against oper_channel. */
+        if ((local->oper_channel != local->hw.conf.channel) ||
+            (local->_oper_channel_type != local->hw.conf.channel_type))
+                return false;
+
+        return true;
+}
+
 int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 {
         struct ieee80211_channel *chan, *scan_chan;
@@ -110,21 +145,27 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 
         scan_chan = local->scan_channel;
 
+        /* If this off-channel logic ever changes,  ieee80211_on_oper_channel
+         * may need to change as well.
+         */
         offchannel_flag = local->hw.conf.flags & IEEE80211_CONF_OFFCHANNEL;
         if (scan_chan) {
                 chan = scan_chan;
                 channel_type = NL80211_CHAN_NO_HT;
-                local->hw.conf.flags |= IEEE80211_CONF_OFFCHANNEL;
-        } else if (local->tmp_channel &&
-                   local->oper_channel != local->tmp_channel) {
+        } else if (local->tmp_channel) {
                 chan = scan_chan = local->tmp_channel;
                 channel_type = local->tmp_channel_type;
-                local->hw.conf.flags |= IEEE80211_CONF_OFFCHANNEL;
         } else {
                 chan = local->oper_channel;
                 channel_type = local->_oper_channel_type;
-                local->hw.conf.flags &= ~IEEE80211_CONF_OFFCHANNEL;
         }
+
+        if (chan != local->oper_channel ||
+            channel_type != local->_oper_channel_type)
+                local->hw.conf.flags |= IEEE80211_CONF_OFFCHANNEL;
+        else
+                local->hw.conf.flags &= ~IEEE80211_CONF_OFFCHANNEL;
+
         offchannel_flag ^= local->hw.conf.flags & IEEE80211_CONF_OFFCHANNEL;
 
         if (offchannel_flag || chan != local->hw.conf.channel ||
@@ -231,7 +272,7 @@ void ieee80211_bss_info_change_notify(struct ieee80211_sub_if_data *sdata,
 
         if (changed & BSS_CHANGED_BEACON_ENABLED) {
                 if (local->quiescing || !ieee80211_sdata_running(sdata) ||
-                    test_bit(SCAN_SW_SCANNING, &local->scanning)) {
+                    test_bit(SDATA_STATE_OFFCHANNEL, &sdata->state)) {
                         sdata->vif.bss_conf.enable_beacon = false;
                 } else {
                         /*