[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, 5 insertions, 2 deletions

diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index e7904db55325..8292431ac48f 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -1061,7 +1061,10 @@ static int ieee80211_ioctl_prism2_param(struct net_device *dev,
                 break;
 
         case PRISM2_PARAM_PREAMBLE:
-                local->short_preamble = value;
+                if (sdata->type != IEEE80211_IF_TYPE_AP)
+                        ret = -ENOENT;
+                else
+                        sdata->short_preamble = value;
                 break;
 
         case PRISM2_PARAM_STAT_TIME:
@@ -1184,7 +1187,7 @@ static int ieee80211_ioctl_get_prism2_param(struct net_device *dev,
                 break;
 
         case PRISM2_PARAM_PREAMBLE:
-                *param = local->short_preamble;
+                *param = sdata->short_preamble;
                 break;
 
         case PRISM2_PARAM_STAT_TIME: