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Commit 49ddf8e6 authored by Johannes Berg's avatar Johannes Berg
Browse files

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: default avatarJohannes Berg <johannes.berg@intel.com>
parent 0f9c5a61

include/linux/ieee80211.h

+10 −0
Original line number Diff line number Diff line
@@ -638,6 +638,16 @@ static inline bool ieee80211_is_first_frag(__le16 seq_ctrl) 
	return (seq_ctrl & cpu_to_le16(IEEE80211_SCTL_FRAG)) == 0;

}



/**

 * ieee80211_is_frag - check if a frame is a fragment

 * @hdr: 802.11 header of the frame

 */

static inline bool ieee80211_is_frag(struct ieee80211_hdr *hdr)

{

	return ieee80211_has_morefrags(hdr->frame_control) ||

	       hdr->seq_ctrl & cpu_to_le16(IEEE80211_SCTL_FRAG);

}



struct ieee80211s_hdr {

	u8 flags;

	u8 ttl;

net/mac80211/cfg.c

+7 −3
Original line number Diff line number Diff line
@@ -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) {

net/mac80211/ieee80211_i.h

+5 −0
Original line number Diff line number Diff line
@@ -1494,6 +1494,11 @@ u64 ieee80211_mgmt_tx_cookie(struct ieee80211_local *local); 
int ieee80211_attach_ack_skb(struct ieee80211_local *local, struct sk_buff *skb,

			     u64 *cookie, gfp_t gfp);



void ieee80211_check_fast_rx(struct sta_info *sta);

void __ieee80211_check_fast_rx_iface(struct ieee80211_sub_if_data *sdata);

void ieee80211_check_fast_rx_iface(struct ieee80211_sub_if_data *sdata);

void ieee80211_clear_fast_rx(struct sta_info *sta);



/* STA code */

void ieee80211_sta_setup_sdata(struct ieee80211_sub_if_data *sdata);

int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,

net/mac80211/key.c

+1 −0
Original line number Diff line number Diff line
@@ -338,6 +338,7 @@ static void ieee80211_key_replace(struct ieee80211_sub_if_data *sdata, 
		} else {

			rcu_assign_pointer(sta->gtk[idx], new);

		}

		ieee80211_check_fast_rx(sta);

	} else {

		defunikey = old &&

			old == key_mtx_dereference(sdata->local,

net/mac80211/mlme.c

+9 −0
Original line number Diff line number Diff line
@@ -2217,6 +2217,7 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata) 
	const u8 *ssid;

	u8 *dst = ifmgd->associated->bssid;

	u8 unicast_limit = max(1, max_probe_tries - 3);

	struct sta_info *sta;



	/*

	 * Try sending broadcast probe requests for the last three
@@ -2235,6 +2236,14 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata) 
	 */

	ifmgd->probe_send_count++;



	if (dst) {

		mutex_lock(&sdata->local->sta_mtx);

		sta = sta_info_get(sdata, dst);

		if (!WARN_ON(!sta))

			ieee80211_check_fast_rx(sta);

		mutex_unlock(&sdata->local->sta_mtx);

	}



	if (ieee80211_hw_check(&sdata->local->hw, REPORTS_TX_ACK_STATUS)) {

		ifmgd->nullfunc_failed = false;

		ieee80211_send_nullfunc(sdata->local, sdata, false);