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>
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 4233c3d..d56b9da 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -365,12 +365,11 @@
ieee80211_bss_info_change_notify(
sdata, BSS_CHANGED_BEACON_ENABLED);
- if (sdata->vif.type == NL80211_IFTYPE_STATION) {
- if (sdata->u.mgd.associated) {
- netif_tx_stop_all_queues(sdata->dev);
- ieee80211_scan_ps_enable(sdata);
- }
- } else
+ /*
+ * only handle non-STA interfaces here, STA interfaces
+ * are handled in the scan state machine
+ */
+ if (sdata->vif.type != NL80211_IFTYPE_STATION)
netif_tx_stop_all_queues(sdata->dev);
}
mutex_unlock(&local->iflist_mtx);
@@ -474,17 +473,113 @@
static int ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long *next_delay)
{
- /* if no more bands/channels left, complete scan */
+ 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))
+ continue;
+
+ if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+ if (sdata->u.mgd.associated) {
+ associated = true;
+ break;
+ }
+ }
+ }
+ mutex_unlock(&local->iflist_mtx);
+
+ 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->scan_state = SCAN_ENTER_OPER_CHANNEL;
+ else
+ local->scan_state = SCAN_SET_CHANNEL;
+ } else {
+ /*
+ * we're on the operating channel currently, let's
+ * leave that channel now to scan another one
+ */
+ local->scan_state = SCAN_LEAVE_OPER_CHANNEL;
+ }
+
*next_delay = 0;
- local->scan_state = SCAN_SET_CHANNEL;
return 0;
}
+static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
+ unsigned long *next_delay)
+{
+ 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 (!netif_running(sdata->dev))
+ continue;
+
+ if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+ netif_tx_stop_all_queues(sdata->dev);
+ if (sdata->u.mgd.associated)
+ ieee80211_scan_ps_enable(sdata);
+ }
+ }
+ mutex_unlock(&local->iflist_mtx);
+
+ __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
+
+ /* advance to the next channel to be scanned */
+ *next_delay = HZ / 10;
+ local->scan_state = SCAN_SET_CHANNEL;
+}
+
+static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
+ unsigned long *next_delay)
+{
+ struct ieee80211_sub_if_data *sdata = local->scan_sdata;
+
+ /* switch back to the operating channel */
+ local->scan_channel = NULL;
+ ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+
+ /*
+ * notify the AP about us being back and restart all STA interfaces
+ */
+ 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.mgd.associated)
+ ieee80211_scan_ps_disable(sdata);
+ netif_tx_wake_all_queues(sdata->dev);
+ }
+ }
+ mutex_unlock(&local->iflist_mtx);
+
+ __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
+
+ *next_delay = HZ / 5;
+ local->scan_state = SCAN_DECISION;
+}
+
static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
unsigned long *next_delay)
{
@@ -609,6 +704,12 @@
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);