[MAC80211]: improved short preamble handling

Similarly to CTS protection, whether short preambles are used for 802.11b
transmissions should be a per-subif setting, not device global.

For STAs, this patch makes short preamble handling automatic based on the ERP
IE. For APs, hostapd still uses the prism ioctls, but the write ioctl has been
restricted to AP-only subifs.

ieee80211_txrx_data.short_preamble (an unused field) was removed.

Unfortunately, some API changes were required for the following functions:
 - ieee80211_generic_frame_duration
 - ieee80211_rts_duration
 - ieee80211_ctstoself_duration
 - ieee80211_rts_get
 - ieee80211_ctstoself_get
Affected drivers were updated accordingly.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
index 8e6548974a9f..0f5f8131bd71 100644
--- a/net/mac80211/ieee80211_sta.c
+++ b/net/mac80211/ieee80211_sta.c
@@ -318,6 +318,7 @@ static void ieee80211_handle_erp_ie(struct net_device *dev, u8 erp_value)
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         struct ieee80211_if_sta *ifsta = &sdata->u.sta;
         int use_protection = (erp_value & WLAN_ERP_USE_PROTECTION) != 0;
+        int preamble_mode = (erp_value & WLAN_ERP_BARKER_PREAMBLE) != 0;
 
         if (use_protection != sdata->use_protection) {
                 if (net_ratelimit()) {
@@ -329,6 +330,18 @@ static void ieee80211_handle_erp_ie(struct net_device *dev, u8 erp_value)
                 }
                 sdata->use_protection = use_protection;
         }
+
+        if (!preamble_mode != sdata->short_preamble) {
+                if (net_ratelimit()) {
+                        printk(KERN_DEBUG "%s: switched to %s barker preamble"
+                               " (BSSID=" MAC_FMT ")\n",
+                               dev->name,
+                               (preamble_mode == WLAN_ERP_PREAMBLE_SHORT) ?
+                                        "short" : "long",
+                               MAC_ARG(ifsta->bssid));
+                }
+                sdata->short_preamble = !preamble_mode;
+        }
 }
 
 
@@ -415,6 +428,7 @@ static void ieee80211_set_associated(struct net_device *dev,
                 ieee80211_sta_send_associnfo(dev, ifsta);
         } else {
                 netif_carrier_off(dev);
+                sdata->short_preamble = 0;
                 sdata->use_protection = 0;
                 memset(wrqu.ap_addr.sa_data, 0, ETH_ALEN);
         }
@@ -2281,7 +2295,7 @@ static int ieee80211_sta_join_ibss(struct net_device *dev,
                                "for IBSS beacon\n", dev->name);
                         break;
                 }
-                control.tx_rate = (local->short_preamble &&
+                control.tx_rate = (sdata->short_preamble &&
                                    (rate->flags & IEEE80211_RATE_PREAMBLE2)) ?
                         rate->val2 : rate->val;
                 control.antenna_sel_tx = local->hw.conf.antenna_sel_tx;