mac80211: add fast-rx path

The regular RX path has a lot of code, but with a few
assumptions on the hardware it's possible to reduce the
amount of code significantly. Currently the assumptions
on the driver are the following:
 * hardware/driver reordering buffer (if supporting aggregation)
 * hardware/driver decryption & PN checking (if using encryption)
 * hardware/driver did de-duplication
 * hardware/driver did A-MSDU deaggregation
 * AP_LINK_PS is used (in AP mode)
 * no client powersave handling in mac80211 (in client mode)

of which some are actually checked per packet:
 * de-duplication
 * PN checking
 * decryption
and additionally packets must
 * not be A-MSDU (have been deaggregated by driver/device)
 * be data packets
 * not be fragmented
 * be unicast
 * have RFC 1042 header

Additionally dynamically we assume:
 * no encryption or CCMP/GCMP, TKIP/WEP/other not allowed
 * station must be authorized
 * 4-addr format not enabled

Some data needed for the RX path is cached in a new per-station
"fast_rx" structure, so that we only need to look at this and
the packet, no other memory when processing packets on the fast
RX path.

After doing the above per-packet checks, the data path collapses
down to a pretty simple conversion function taking advantage of
the data cached in the small fast_rx struct.

This should speed up the RX processing, and will make it easier
to reason about parallelizing RX (for which statistics will need
to be per-CPU still.)

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

1 files changed, 7 insertions, 3 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 62a90f270f03..fc4730b938d0 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -65,11 +65,13 @@ static int ieee80211_change_iface(struct wiphy *wiphy,
 		return ret;
 
 	if (type == NL80211_IFTYPE_AP_VLAN &&
-	    params && params->use_4addr == 0)
+	    params && params->use_4addr == 0) {
 		RCU_INIT_POINTER(sdata->u.vlan.sta, NULL);
-	else if (type == NL80211_IFTYPE_STATION &&
-		 params && params->use_4addr >= 0)
+		ieee80211_check_fast_rx_iface(sdata);
+	} else if (type == NL80211_IFTYPE_STATION &&
+		   params && params->use_4addr >= 0) {
 		sdata->u.mgd.use_4addr = params->use_4addr;
+	}
 
 	if (sdata->vif.type == NL80211_IFTYPE_MONITOR && flags) {
 		struct ieee80211_local *local = sdata->local;
@@ -1367,6 +1369,7 @@ static int ieee80211_change_station(struct wiphy *wiphy,
 
 			rcu_assign_pointer(vlansdata->u.vlan.sta, sta);
 			new_4addr = true;
+			__ieee80211_check_fast_rx_iface(vlansdata);
 		}
 
 		if (sta->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
@@ -1889,6 +1892,7 @@ static int ieee80211_change_bss(struct wiphy *wiphy,
 			sdata->flags |= IEEE80211_SDATA_DONT_BRIDGE_PACKETS;
 		else
 			sdata->flags &= ~IEEE80211_SDATA_DONT_BRIDGE_PACKETS;
+		ieee80211_check_fast_rx_iface(sdata);
 	}
 
 	if (params->ht_opmode >= 0) {