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, 55 insertions, 11 deletions

diff --git a/net/mac80211/work.c b/net/mac80211/work.c
index 36305e0d06ef..6bf787a5b38a 100644
--- a/net/mac80211/work.c
+++ b/net/mac80211/work.c
@@ -924,18 +924,44 @@ static void ieee80211_work_work(struct work_struct *work)
                 }
 
                 if (!started && !local->tmp_channel) {
-                        /*
-                         * TODO: could optimize this by leaving the
-                         *       station vifs in awake mode if they
-                         *       happen to be on the same channel as
-                         *       the requested channel
-                         */
-                        ieee80211_offchannel_stop_beaconing(local);
-                        ieee80211_offchannel_stop_station(local);
+                        bool on_oper_chan;
+                        bool tmp_chan_changed = false;
+                        bool on_oper_chan2;
+                        on_oper_chan = ieee80211_cfg_on_oper_channel(local);
+                        if (local->tmp_channel)
+                                if ((local->tmp_channel != wk->chan) ||
+                                    (local->tmp_channel_type != wk->chan_type))
+                                        tmp_chan_changed = true;
 
                         local->tmp_channel = wk->chan;
                         local->tmp_channel_type = wk->chan_type;
-                        ieee80211_hw_config(local, 0);
+                        /*
+                         * Leave the station vifs in awake mode if they
+                         * happen to be on the same channel as
+                         * the requested channel.
+                         */
+                        on_oper_chan2 = ieee80211_cfg_on_oper_channel(local);
+                        if (on_oper_chan != on_oper_chan2) {
+                                if (on_oper_chan2) {
+                                        /* going off oper channel, PS too */
+                                        ieee80211_offchannel_stop_vifs(local,
+                                                                       true);
+                                        ieee80211_hw_config(local, 0);
+                                } else {
+                                        /* going on channel, but leave PS
+                                         * off-channel. */
+                                        ieee80211_hw_config(local, 0);
+                                        ieee80211_offchannel_return(local,
+                                                                    true,
+                                                                    false);
+                                }
+                        } else if (tmp_chan_changed)
+                                /* Still off-channel, but on some other
+                                 * channel, so update hardware.
+                                 * PS should already be off-channel.
+                                 */
+                                ieee80211_hw_config(local, 0);
+
                         started = true;
                         wk->timeout = jiffies;
                 }
@@ -1011,9 +1037,27 @@ static void ieee80211_work_work(struct work_struct *work)
         }
 
         if (!remain_off_channel && local->tmp_channel) {
+                bool on_oper_chan = ieee80211_cfg_on_oper_channel(local);
                 local->tmp_channel = NULL;
-                ieee80211_hw_config(local, 0);
-                ieee80211_offchannel_return(local, true);
+                /* If tmp_channel wasn't operating channel, then
+                 * we need to go back on-channel.
+                 * NOTE:  If we can ever be here while scannning,
+                 * or if the hw_config() channel config logic changes,
+                 * then we may need to do a more thorough check to see if
+                 * we still need to do a hardware config.  Currently,
+                 * we cannot be here while scanning, however.
+                 */
+                if (ieee80211_cfg_on_oper_channel(local) && !on_oper_chan)
+                        ieee80211_hw_config(local, 0);
+
+                /* At the least, we need to disable offchannel_ps,
+                 * so just go ahead and run the entire offchannel
+                 * return logic here.  We *could* skip enabling
+                 * beaconing if we were already on-oper-channel
+                 * as a future optimization.
+                 */
+                ieee80211_offchannel_return(local, true, true);
+
                 /* give connection some time to breathe */
                 run_again(local, jiffies + HZ/2);
         }