mac80211: rework scanning to account for probe response/beacon difference

This patch reworks the scanning code (ieee80211_rx_bss_info) to take
more parameters from beacons and keep a BSS info structure alive when
only beacons for it are received. This fixes a problem with iwlwifi
drivers (where we don't understand the root cause of the problem yet)
and another driver for some broken hardware (which cannot send probe
requests unless associated, so can't always actively scan.)

Signed-off-by: Bill Moss <bmoss@clemson.edu>
[jmberg: reformatted comments, make probe_resp a bool]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index ce566f3e0169a9e62f2b458c698753a543a25626..8e53ce7ed44485ee0afe2a347a49555d9d1a22a5 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -102,7 +102,7 @@ struct ieee80211_sta_bss {
        u64 timestamp;
        int beacon_int;
 
-       int probe_resp;
+       bool probe_resp;
        unsigned long last_update;
 
        /* during assocation, we save an ERP value from a probe response so

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index e3f2cb086588744ece78e350b64a4d4cc3df3f51..6b75cb6c63008370a081dfc68e1a892cdd02d0dd 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2588,22 +2588,29 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
 #endif
        }
 
-       bss->band = rx_status->band;
-
-       if (sdata->vif.type != IEEE80211_IF_TYPE_IBSS &&
-           bss->probe_resp && beacon) {
-               /* STA mode:
-                * Do not allow beacon to override data from Probe Response. */
-               ieee80211_rx_bss_put(dev, bss);
-               return;
-       }
-
        /* save the ERP value so that it is available at association time */
        if (elems.erp_info && elems.erp_info_len >= 1) {
                bss->erp_value = elems.erp_info[0];
                bss->has_erp_value = 1;
        }
 
+       if (elems.ht_cap_elem &&
+            (!bss->ht_ie || bss->ht_ie_len != elems.ht_cap_elem_len ||
+            memcmp(bss->ht_ie, elems.ht_cap_elem, elems.ht_cap_elem_len))) {
+               kfree(bss->ht_ie);
+               bss->ht_ie = kmalloc(elems.ht_cap_elem_len + 2, GFP_ATOMIC);
+               if (bss->ht_ie) {
+                       memcpy(bss->ht_ie, elems.ht_cap_elem - 2,
+                               elems.ht_cap_elem_len + 2);
+                       bss->ht_ie_len = elems.ht_cap_elem_len + 2;
+               } else
+                       bss->ht_ie_len = 0;
+       } else if (!elems.ht_cap_elem && bss->ht_ie) {
+               kfree(bss->ht_ie);
+               bss->ht_ie = NULL;
+               bss->ht_ie_len = 0;
+       }
+
        bss->beacon_int = le16_to_cpu(mgmt->u.beacon.beacon_int);
        bss->capability = le16_to_cpu(mgmt->u.beacon.capab_info);
 
@@ -2625,6 +2632,26 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
                bss->supp_rates_len += clen;
        }
 
+       bss->band = rx_status->band;
+
+       bss->timestamp = beacon_timestamp;
+       bss->last_update = jiffies;
+       bss->rssi = rx_status->ssi;
+       bss->signal = rx_status->signal;
+       bss->noise = rx_status->noise;
+       if (!beacon && !bss->probe_resp)
+               bss->probe_resp = true;
+
+       /*
+        * In STA mode, the remaining parameters should not be overridden
+        * by beacons because they're not necessarily accurate there.
+        */
+       if (sdata->vif.type != IEEE80211_IF_TYPE_IBSS &&
+           bss->probe_resp && beacon) {
+               ieee80211_rx_bss_put(dev, bss);
+               return;
+       }
+
        if (elems.wpa &&
            (!bss->wpa_ie || bss->wpa_ie_len != elems.wpa_len ||
             memcmp(bss->wpa_ie, elems.wpa, elems.wpa_len))) {
@@ -2657,6 +2684,20 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
                bss->rsn_ie_len = 0;
        }
 
+       /*
+        * Cf.
+        * http://www.wipo.int/pctdb/en/wo.jsp?wo=2007047181&IA=WO2007047181&DISPLAY=DESC
+        *
+        * quoting:
+        *
+        * In particular, "Wi-Fi CERTIFIED for WMM - Support for Multimedia
+        * Applications with Quality of Service in Wi-Fi Networks," Wi- Fi
+        * Alliance (September 1, 2004) is incorporated by reference herein.
+        * The inclusion of the WMM Parameters in probe responses and
+        * association responses is mandatory for WMM enabled networks. The
+        * inclusion of the WMM Parameters in beacons, however, is optional.
+        */
+
        if (elems.wmm_param &&
            (!bss->wmm_ie || bss->wmm_ie_len != elems.wmm_param_len ||
             memcmp(bss->wmm_ie, elems.wmm_param, elems.wmm_param_len))) {
@@ -2673,30 +2714,6 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
                bss->wmm_ie = NULL;
                bss->wmm_ie_len = 0;
        }
-       if (elems.ht_cap_elem &&
-           (!bss->ht_ie || bss->ht_ie_len != elems.ht_cap_elem_len ||
-            memcmp(bss->ht_ie, elems.ht_cap_elem, elems.ht_cap_elem_len))) {
-               kfree(bss->ht_ie);
-               bss->ht_ie = kmalloc(elems.ht_cap_elem_len + 2, GFP_ATOMIC);
-               if (bss->ht_ie) {
-                       memcpy(bss->ht_ie, elems.ht_cap_elem - 2,
-                              elems.ht_cap_elem_len + 2);
-                       bss->ht_ie_len = elems.ht_cap_elem_len + 2;
-               } else
-                       bss->ht_ie_len = 0;
-       } else if (!elems.ht_cap_elem && bss->ht_ie) {
-               kfree(bss->ht_ie);
-               bss->ht_ie = NULL;
-               bss->ht_ie_len = 0;
-       }
-
-       bss->timestamp = beacon_timestamp;
-       bss->last_update = jiffies;
-       bss->rssi = rx_status->ssi;
-       bss->signal = rx_status->signal;
-       bss->noise = rx_status->noise;
-       if (!beacon)
-               bss->probe_resp++;
 
        /* check if we need to merge IBSS */
        if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS && beacon &&