mac80211: improve the rate control API

Allow rate control modules to pass a rate selection table to mac80211
and the driver. This allows drivers to fetch the most recent rate
selection from the sta pointer for already buffered frames. This allows
rate control to respond faster to sudden link changes and it is also a
step towards adding minstrel_ht support to drivers like iwlwifi.

When a driver sets IEEE80211_HW_SUPPORTS_RC_TABLE, mac80211 will not
fill info->control.rates with rates from the rate table (to preserve
explicit overrides by the rate control module). The driver then
explicitly calls ieee80211_get_tx_rates to merge overrides from
info->control.rates with defaults from the sta rate table.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 34 insertions, 108 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 6ca857f8f42..4a5fbf83cd1 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -48,15 +48,15 @@ static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 
 	/* assume HW handles this */
-	if (info->control.rates[0].flags & IEEE80211_TX_RC_MCS)
+	if (tx->rate.flags & IEEE80211_TX_RC_MCS)
 		return 0;
 
 	/* uh huh? */
-	if (WARN_ON_ONCE(info->control.rates[0].idx < 0))
+	if (WARN_ON_ONCE(tx->rate.idx < 0))
 		return 0;
 
 	sband = local->hw.wiphy->bands[info->band];
-	txrate = &sband->bitrates[info->control.rates[0].idx];
+	txrate = &sband->bitrates[tx->rate.idx];
 
 	erp = txrate->flags & IEEE80211_RATE_ERP_G;
 
@@ -617,11 +617,9 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
 	struct ieee80211_hdr *hdr = (void *)tx->skb->data;
 	struct ieee80211_supported_band *sband;
-	struct ieee80211_rate *rate;
-	int i;
 	u32 len;
-	bool inval = false, rts = false, short_preamble = false;
 	struct ieee80211_tx_rate_control txrc;
+	struct ieee80211_sta_rates *ratetbl = NULL;
 	bool assoc = false;
 
 	memset(&txrc, 0, sizeof(txrc));
@@ -653,10 +651,10 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 
 	/* set up RTS protection if desired */
 	if (len > tx->local->hw.wiphy->rts_threshold) {
-		txrc.rts = rts = true;
+		txrc.rts = true;
 	}
 
-	info->control.use_rts = rts;
+	info->control.use_rts = txrc.rts;
 	info->control.use_cts_prot = tx->sdata->vif.bss_conf.use_cts_prot;
 
 	/*
@@ -668,7 +666,9 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 	if (tx->sdata->vif.bss_conf.use_short_preamble &&
 	    (ieee80211_is_data(hdr->frame_control) ||
 	     (tx->sta && test_sta_flag(tx->sta, WLAN_STA_SHORT_PREAMBLE))))
-		txrc.short_preamble = short_preamble = true;
+		txrc.short_preamble = true;
+
+	info->control.short_preamble = txrc.short_preamble;
 
 	if (tx->sta)
 		assoc = test_sta_flag(tx->sta, WLAN_STA_ASSOC);
@@ -692,16 +692,38 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 	 */
 	rate_control_get_rate(tx->sdata, tx->sta, &txrc);
 
-	if (unlikely(info->control.rates[0].idx < 0))
-		return TX_DROP;
+	if (tx->sta && !info->control.skip_table)
+		ratetbl = rcu_dereference(tx->sta->sta.rates);
+
+	if (unlikely(info->control.rates[0].idx < 0)) {
+		if (ratetbl) {
+			struct ieee80211_tx_rate rate = {
+				.idx = ratetbl->rate[0].idx,
+				.flags = ratetbl->rate[0].flags,
+				.count = ratetbl->rate[0].count
+			};
+
+			if (ratetbl->rate[0].idx < 0)
+				return TX_DROP;
+
+			tx->rate = rate;
+		} else {
+			return TX_DROP;
+		}
+	} else {
+		tx->rate = info->control.rates[0];
+	}
 
 	if (txrc.reported_rate.idx < 0) {
-		txrc.reported_rate = info->control.rates[0];
+		txrc.reported_rate = tx->rate;
 		if (tx->sta && ieee80211_is_data(hdr->frame_control))
 			tx->sta->last_tx_rate = txrc.reported_rate;
 	} else if (tx->sta)
 		tx->sta->last_tx_rate = txrc.reported_rate;
 
+	if (ratetbl)
+		return TX_CONTINUE;
+
 	if (unlikely(!info->control.rates[0].count))
 		info->control.rates[0].count = 1;
 
@@ -709,102 +731,6 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 			 (info->flags & IEEE80211_TX_CTL_NO_ACK)))
 		info->control.rates[0].count = 1;
 
-	if (is_multicast_ether_addr(hdr->addr1)) {
-		/*
-		 * XXX: verify the rate is in the basic rateset
-		 */
-		return TX_CONTINUE;
-	}
-
-	/*
-	 * Set up the RTS/CTS rate as the fastest basic rate
-	 * that is not faster than the data rate unless there
-	 * is no basic rate slower than the data rate, in which
-	 * case we pick the slowest basic rate
-	 *
-	 * XXX: Should this check all retry rates?
-	 */
-	if (!(info->control.rates[0].flags & IEEE80211_TX_RC_MCS)) {
-		u32 basic_rates = tx->sdata->vif.bss_conf.basic_rates;
-		s8 baserate = basic_rates ? ffs(basic_rates - 1) : 0;
-
-		rate = &sband->bitrates[info->control.rates[0].idx];
-
-		for (i = 0; i < sband->n_bitrates; i++) {
-			/* must be a basic rate */
-			if (!(basic_rates & BIT(i)))
-				continue;
-			/* must not be faster than the data rate */
-			if (sband->bitrates[i].bitrate > rate->bitrate)
-				continue;
-			/* maximum */
-			if (sband->bitrates[baserate].bitrate <
-			     sband->bitrates[i].bitrate)
-				baserate = i;
-		}
-
-		info->control.rts_cts_rate_idx = baserate;
-	}
-
-	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
-		struct ieee80211_tx_rate *rc_rate = &info->control.rates[i];
-
-		/*
-		 * make sure there's no valid rate following
-		 * an invalid one, just in case drivers don't
-		 * take the API seriously to stop at -1.
-		 */
-		if (inval) {
-			rc_rate->idx = -1;
-			continue;
-		}
-		if (rc_rate->idx < 0) {
-			inval = true;
-			continue;
-		}
-
-		/*
-		 * For now assume MCS is already set up correctly, this
-		 * needs to be fixed.
-		 */
-		if (rc_rate->flags & IEEE80211_TX_RC_MCS) {
-			WARN_ON(rc_rate->idx > 76);
-
-			if (!(rc_rate->flags & IEEE80211_TX_RC_USE_RTS_CTS) &&
-			    tx->sdata->vif.bss_conf.use_cts_prot)
-				rc_rate->flags |=
-					IEEE80211_TX_RC_USE_CTS_PROTECT;
-			continue;
-		}
-
-		if (rc_rate->flags & IEEE80211_TX_RC_VHT_MCS) {
-			WARN_ON(ieee80211_rate_get_vht_mcs(rc_rate) > 9);
-			continue;
-		}
-
-		/* set up RTS protection if desired */
-		if (rts)
-			rc_rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
-
-		/* RC is busted */
-		if (WARN_ON_ONCE(rc_rate->idx >= sband->n_bitrates)) {
-			rc_rate->idx = -1;
-			continue;
-		}
-
-		rate = &sband->bitrates[rc_rate->idx];
-
-		/* set up short preamble */
-		if (short_preamble &&
-		    rate->flags & IEEE80211_RATE_SHORT_PREAMBLE)
-			rc_rate->flags |= IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
-
-		/* set up G protection */
-		if (!rts && tx->sdata->vif.bss_conf.use_cts_prot &&
-		    rate->flags & IEEE80211_RATE_ERP_G)
-			rc_rate->flags |= IEEE80211_TX_RC_USE_CTS_PROTECT;
-	}
-
 	return TX_CONTINUE;
 }