mac80211: add WMM admission control support

Use the currently existing APIs between mac80211 and the low
level driver to implement WMM admission control.

The low level driver needs to report the media time used by
each transmitted packet in ieee80211_tx_status. Based on that
information, mac80211 will modify the QoS parameters of the
admission controlled Access Category when the limit is
reached. Once the original QoS parameters can be restored,
mac80211 will do so.

One issue with this approach is that management frames will
also erroneously be downgraded, but the upside is that the
implementation is simple. In the future, it can be extended
to driver- or device-based implementations that are better.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 64deb9a..d6b01ad 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -20,6 +20,7 @@
 #include "cfg.h"
 #include "rate.h"
 #include "mesh.h"
+#include "wme.h"
 
 static struct wireless_dev *ieee80211_add_iface(struct wiphy *wiphy,
 						const char *name,
@@ -3585,6 +3586,76 @@ static int ieee80211_set_ap_chanwidth(struct wiphy *wiphy,
 	return ret;
 }
 
+static int ieee80211_add_tx_ts(struct wiphy *wiphy, struct net_device *dev,
+			       u8 tsid, const u8 *peer, u8 up,
+			       u16 admitted_time)
+{
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+	int ac = ieee802_1d_to_ac[up];
+
+	if (sdata->vif.type != NL80211_IFTYPE_STATION)
+		return -EOPNOTSUPP;
+
+	if (!(sdata->wmm_acm & BIT(up)))
+		return -EINVAL;
+
+	if (ifmgd->tx_tspec[ac].admitted_time)
+		return -EBUSY;
+
+	if (admitted_time) {
+		ifmgd->tx_tspec[ac].admitted_time = 32 * admitted_time;
+		ifmgd->tx_tspec[ac].tsid = tsid;
+		ifmgd->tx_tspec[ac].up = up;
+	}
+
+	return 0;
+}
+
+static int ieee80211_del_tx_ts(struct wiphy *wiphy, struct net_device *dev,
+			       u8 tsid, const u8 *peer)
+{
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+	struct ieee80211_local *local = wiphy_priv(wiphy);
+	int ac;
+
+	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+		struct ieee80211_sta_tx_tspec *tx_tspec = &ifmgd->tx_tspec[ac];
+
+		/* skip unused entries */
+		if (!tx_tspec->admitted_time)
+			continue;
+
+		if (tx_tspec->tsid != tsid)
+			continue;
+
+		/* due to this new packets will be reassigned to non-ACM ACs */
+		tx_tspec->up = -1;
+
+		/* Make sure that all packets have been sent to avoid to
+		 * restore the QoS params on packets that are still on the
+		 * queues.
+		 */
+		synchronize_net();
+		ieee80211_flush_queues(local, sdata);
+
+		/* restore the normal QoS parameters
+		 * (unconditionally to avoid races)
+		 */
+		tx_tspec->action = TX_TSPEC_ACTION_STOP_DOWNGRADE;
+		tx_tspec->downgraded = false;
+		ieee80211_sta_handle_tspec_ac_params(sdata);
+
+		/* finally clear all the data */
+		memset(tx_tspec, 0, sizeof(*tx_tspec));
+
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
 const struct cfg80211_ops mac80211_config_ops = {
 	.add_virtual_intf = ieee80211_add_iface,
 	.del_virtual_intf = ieee80211_del_iface,
@@ -3663,4 +3734,6 @@ const struct cfg80211_ops mac80211_config_ops = {
 	.channel_switch = ieee80211_channel_switch,
 	.set_qos_map = ieee80211_set_qos_map,
 	.set_ap_chanwidth = ieee80211_set_ap_chanwidth,
+	.add_tx_ts = ieee80211_add_tx_ts,
+	.del_tx_ts = ieee80211_del_tx_ts,
 };