@@ -745,6 +745,7 @@ struct ieee80211_local {
int scan_channel_idx;
int scan_ies_len;
+ unsigned long leave_oper_channel_time;
enum mac80211_scan_state next_scan_state;
struct delayed_work scan_work;
struct ieee80211_sub_if_data *scan_sdata;
@@ -14,6 +14,8 @@
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
+#include <linux/pm_qos_params.h>
+#include <net/sch_generic.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
@@ -321,6 +323,7 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local)
ieee80211_offchannel_stop_beaconing(local);
+ local->leave_oper_channel_time = 0;
local->next_scan_state = SCAN_DECISION;
local->scan_channel_idx = 0;
@@ -425,11 +428,26 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
return rc;
}
+static unsigned long
+ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
+{
+ /*
+ * TODO: channel switching also consumes quite some time,
+ * add that delay as well to get a better estimation
+ */
+ if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
+ return IEEE80211_PASSIVE_CHANNEL_TIME;
+ return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
+}
+
static int ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long *next_delay)
{
bool associated = false;
+ bool tx_empty = true;
+ bool bad_latency;
struct ieee80211_sub_if_data *sdata;
+ struct ieee80211_channel *next_chan;
/* if no more bands/channels left, complete scan and advance to the idle state */
if (local->scan_channel_idx >= local->scan_req->n_channels) {
@@ -437,7 +455,10 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local,
return 1;
}
- /* check if at least one STA interface is associated */
+ /*
+ * check if at least one STA interface is associated
+ * and if it has pending tx frames
+ */
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
if (!ieee80211_sdata_running(sdata))
@@ -446,7 +467,10 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local,
if (sdata->vif.type == NL80211_IFTYPE_STATION) {
if (sdata->u.mgd.associated) {
associated = true;
- break;
+ if (!qdisc_all_tx_empty(sdata->dev)) {
+ tx_empty = false;
+ break;
+ }
}
}
}
@@ -455,11 +479,24 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local,
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
+ * see if we can scan another channel without interfering
+ * with the current traffic situation.
+ *
+ * Since we don't know if the AP has pending frames for us
+ * we can only check for our tx queues and use the current
+ * pm_qos requirements for rx. Hence, if no tx traffic occurs
+ * at all we will scan as many channels in a row as the pm_qos
+ * latency allows us to.
+ *
+ * Otherwise switch back to the operating channel.
*/
- if (associated)
+ next_chan = local->scan_req->channels[local->scan_channel_idx];
+ bad_latency = time_after(jiffies +
+ ieee80211_scan_get_channel_time(next_chan),
+ local->leave_oper_channel_time +
+ usecs_to_jiffies(pm_qos_requirement(PM_QOS_NETWORK_LATENCY)));
+
+ if (associated && ( !tx_empty || bad_latency))
local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
else
local->next_scan_state = SCAN_SET_CHANNEL;
@@ -491,6 +528,9 @@ static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *loca
else
*next_delay = HZ / 10;
+ /* remember when we left the operating channel */
+ local->leave_oper_channel_time = jiffies;
+
/* advance to the next channel to be scanned */
local->next_scan_state = SCAN_SET_CHANNEL;
}
@@ -510,6 +550,7 @@ static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *loca
__clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
+ local->leave_oper_channel_time = jiffies;
*next_delay = HZ / 5;
local->next_scan_state = SCAN_DECISION;
}