mac80211: implement basic background scanning

Introduce a new scan flag "SCAN_OFF_CHANNEL" which basically tells us
that we are currently on a different channel for scanning and cannot
RX/TX. "SCAN_SW_SCANNING" tells us that we are currently running a
software scan but we might as well be on the operating channel to RX/TX.
While "SCAN_SW_SCANNING" is set during the whole scan "SCAN_OFF_CHANNEL"
is set when leaving the operating channel and unset when coming back.

Introduce two new scan states "SCAN_LEAVE_OPER_CHANNEL" and
"SCAN_ENTER_OPER_CHANNEL" which basically implement the functionality we
need to leave the operating channel (send a nullfunc to the AP and stop
the queues) and enter it again (send a nullfunc to the AP and start the
queues again).

Enhance the scan state "SCAN_DECISION" to switch back to the operating
channel after each scanned channel. In the future it sould be simple
to enhance the decision state to scan as much channels in a row as the
qos latency allows us.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 9c1679d124ba..cb95a3116034 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -421,7 +421,8 @@ ieee80211_rx_h_passive_scan(struct ieee80211_rx_data *rx)
         if (unlikely(test_bit(SCAN_HW_SCANNING, &local->scanning)))
                 return ieee80211_scan_rx(rx->sdata, skb);
 
-        if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning))) {
+        if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning) &&
+                     (rx->flags & IEEE80211_RX_IN_SCAN))) {
                 /* drop all the other packets during a software scan anyway */
                 if (ieee80211_scan_rx(rx->sdata, skb) != RX_QUEUED)
                         dev_kfree_skb(skb);
@@ -2136,7 +2137,8 @@ static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
                 return;
         }
 
-        if (unlikely(local->scanning))
+        if (unlikely(test_bit(SCAN_HW_SCANNING, &local->scanning) ||
+                     test_bit(SCAN_OFF_CHANNEL, &local->scanning)))
                 rx.flags |= IEEE80211_RX_IN_SCAN;
 
         ieee80211_parse_qos(&rx);