mac80211: use DECLARE_EWMA for ave_beacon_signal

It doesn't seem problematic to change the weight for the average
beacon signal from 3 to 4, so use DECLARE_EWMA. This also makes
the code easier to maintain since bugs like the one fixed in the
previous patch can't happen as easily.

With a fix from Avraham Stern to invert the sign since EMWA uses
unsigned values only.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 9482f323fd1939002f4e9377a58d5318ece94f7b..f0aee764d9cdcc0d0fe4995db9da5a76bbe59bf1 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -419,6 +419,8 @@ struct ieee80211_sta_tx_tspec {
        bool downgraded;
 };
 
+DECLARE_EWMA(beacon_signal, 16, 4)
+
 struct ieee80211_if_managed {
        struct timer_list timer;
        struct timer_list conn_mon_timer;
@@ -490,13 +492,7 @@ struct ieee80211_if_managed {
 
        s16 p2p_noa_index;
 
-       /*
-        * Weighted average of the signal strength from Beacon frames in the
-        * current BSS. This is in units of 1/16 of the signal unit to maintain
-        * accuracy and to speed up calculations, i.e., the value need to be
-        * divided by 16 to get the actual value.
-        */
-       int ave_beacon_signal;
+       struct ewma_beacon_signal ave_beacon_signal;
 
        /*
         * Number of Beacon frames used in ave_beacon_signal. This can be used

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 79cfc2b35ef0c67279c15e7fc3a5f20dae4b1f2c..c7d316b440ef9d328774a1186478869172b6fc93 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -81,13 +81,6 @@ MODULE_PARM_DESC(probe_wait_ms,
                 "Maximum time(ms) to wait for probe response"
                 " before disconnecting (reason 4).");
 
-/*
- * Weight given to the latest Beacon frame when calculating average signal
- * strength for Beacon frames received in the current BSS. This must be
- * between 1 and 15.
- */
-#define IEEE80211_SIGNAL_AVE_WEIGHT    3
-
 /*
  * How many Beacon frames need to have been used in average signal strength
  * before starting to indicate signal change events.
@@ -3366,21 +3359,19 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
        /* Track average RSSI from the Beacon frames of the current AP */
        if (ifmgd->flags & IEEE80211_STA_RESET_SIGNAL_AVE) {
                ifmgd->flags &= ~IEEE80211_STA_RESET_SIGNAL_AVE;
-               ifmgd->ave_beacon_signal = rx_status->signal * 16;
+               ewma_beacon_signal_init(&ifmgd->ave_beacon_signal);
                ifmgd->last_cqm_event_signal = 0;
                ifmgd->count_beacon_signal = 1;
                ifmgd->last_ave_beacon_signal = 0;
        } else {
-               ifmgd->ave_beacon_signal =
-                       (IEEE80211_SIGNAL_AVE_WEIGHT * rx_status->signal * 16 +
-                        (16 - IEEE80211_SIGNAL_AVE_WEIGHT) *
-                        ifmgd->ave_beacon_signal) / 16;
                ifmgd->count_beacon_signal++;
        }
 
+       ewma_beacon_signal_add(&ifmgd->ave_beacon_signal, -rx_status->signal);
+
        if (ifmgd->rssi_min_thold != ifmgd->rssi_max_thold &&
            ifmgd->count_beacon_signal >= IEEE80211_SIGNAL_AVE_MIN_COUNT) {
-               int sig = ifmgd->ave_beacon_signal / 16;
+               int sig = -ewma_beacon_signal_read(&ifmgd->ave_beacon_signal);
                int last_sig = ifmgd->last_ave_beacon_signal;
                struct ieee80211_event event = {
                        .type = RSSI_EVENT,
@@ -3407,10 +3398,11 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
        if (bss_conf->cqm_rssi_thold &&
            ifmgd->count_beacon_signal >= IEEE80211_SIGNAL_AVE_MIN_COUNT &&
            !(sdata->vif.driver_flags & IEEE80211_VIF_SUPPORTS_CQM_RSSI)) {
-               int sig = ifmgd->ave_beacon_signal / 16;
+               int sig = -ewma_beacon_signal_read(&ifmgd->ave_beacon_signal);
                int last_event = ifmgd->last_cqm_event_signal;
                int thold = bss_conf->cqm_rssi_thold;
                int hyst = bss_conf->cqm_rssi_hyst;
+
                if (sig < thold &&
                    (last_event == 0 || sig < last_event - hyst)) {
                        ifmgd->last_cqm_event_signal = sig;

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index f167056753395b042d74451464091a96e1923ef2..9cabf076d7183a921ca80786729384505b3642ef 100644 (file)
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2543,7 +2543,7 @@ int ieee80211_ave_rssi(struct ieee80211_vif *vif)
                /* non-managed type inferfaces */
                return 0;
        }
-       return ifmgd->ave_beacon_signal / 16;
+       return -ewma_beacon_signal_read(&ifmgd->ave_beacon_signal);
 }
 EXPORT_SYMBOL_GPL(ieee80211_ave_rssi);