cfg80211/mac80211: Use more generic bitrate mask for rate control

Extend struct cfg80211_bitrate_mask to actually use a bitfield mask
instead of just a single fixed or maximum rate index. This change
itself does not modify the behavior (except for debugfs files), but it
prepares cfg80211 and mac80211 for a new nl80211 command for setting
which rates can be used in TX rate control.

Since frames are now going through the rate control algorithm
unconditionally, the internal IEEE80211_TX_INTFL_RCALGO flag can now
be removed. The RC implementations can use the rate_idx_mask value to
optimize their behavior if only a single rate is enabled.

The old max_rate_idx in struct ieee80211_tx_rate_control is maintained
(but commented as deprecated) for backwards compatibility with existing
RC implementations. Once these implementations have been updated to
use the more generic rate_idx_mask, the max_rate_idx value can be
removed.
Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/cfg80211.h

@@ -857,20 +857,11 @@ enum tx_power_setting {
  * cfg80211_bitrate_mask - masks for bitrate control
  */
 struct cfg80211_bitrate_mask {
-/*
- * As discussed in Berlin, this struct really
- * should look like this:
-
 	struct {
 		u32 legacy;
-		u8 mcs[IEEE80211_HT_MCS_MASK_LEN];
+		/* TODO: add support for masking MCS rates; e.g.: */
+		/* u8 mcs[IEEE80211_HT_MCS_MASK_LEN]; */
 	} control[IEEE80211_NUM_BANDS];
-
- * Since we can always fix in-kernel users, let's keep
- * it simpler for now:
- */
-	u32 fixed;   /* fixed bitrate, 0 == not fixed */
-	u32 maxrate; /* in kbps, 0 == no limit */
 };
 /**
  * struct cfg80211_pmksa - PMK Security Association

include/net/mac80211.h

@@ -255,9 +255,6 @@ struct ieee80211_bss_conf {
  * @IEEE80211_TX_CTL_RATE_CTRL_PROBE: internal to mac80211, can be
  *	set by rate control algorithms to indicate probe rate, will
  *	be cleared for fragmented frames (except on the last fragment)
- * @IEEE80211_TX_INTFL_RCALGO: mac80211 internal flag, do not test or
- *	set this flag in the driver; indicates that the rate control
- *	algorithm was used and should be notified of TX status
  * @IEEE80211_TX_INTFL_NEED_TXPROCESSING: completely internal to mac80211,
  *	used to indicate that a pending frame requires TX processing before
  *	it can be sent out.
@@ -287,7 +284,6 @@ enum mac80211_tx_control_flags {
 	IEEE80211_TX_STAT_AMPDU			= BIT(10),
 	IEEE80211_TX_STAT_AMPDU_NO_BACK		= BIT(11),
 	IEEE80211_TX_CTL_RATE_CTRL_PROBE	= BIT(12),
-	IEEE80211_TX_INTFL_RCALGO		= BIT(13),
 	IEEE80211_TX_INTFL_NEED_TXPROCESSING	= BIT(14),
 	IEEE80211_TX_INTFL_RETRIED		= BIT(15),
 	IEEE80211_TX_INTFL_DONT_ENCRYPT		= BIT(16),
@@ -2297,6 +2293,9 @@ enum rate_control_changed {
  * @short_preamble: whether mac80211 will request short-preamble transmission
  *	if the selected rate supports it
  * @max_rate_idx: user-requested maximum rate (not MCS for now)
+ *	(deprecated; this will be removed once drivers get updated to use
+ *	rate_idx_mask)
+ * @rate_idx_mask: user-requested rate mask (not MCS for now)
  * @skb: the skb that will be transmitted, the control information in it needs
  *	to be filled in
  * @ap: whether this frame is sent out in AP mode
@@ -2309,6 +2308,7 @@ struct ieee80211_tx_rate_control {
 	struct ieee80211_tx_rate reported_rate;
 	bool rts, short_preamble;
 	u8 max_rate_idx;
+	u32 rate_idx_mask;
 	bool ap;
 };
 

net/mac80211/cfg.c

@@ -1406,8 +1406,6 @@ static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	int i;
-	u32 target_rate;
-	struct ieee80211_supported_band *sband;
 
 	/*
 	 * This _could_ be supported by providing a hook for
@@ -1417,35 +1415,11 @@ static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
 	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
 		return -EOPNOTSUPP;
 
-	sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
-
-	/*
-	 * target_rate = -1, rate->fixed = 0 means auto only, so use all rates
-	 * target_rate = X, rate->fixed = 1 means only rate X
-	 * target_rate = X, rate->fixed = 0 means all rates <= X
-	 */
-	sdata->max_ratectrl_rateidx = -1;
-	sdata->force_unicast_rateidx = -1;
-
-	if (mask->fixed)
-		target_rate = mask->fixed / 100;
-	else if (mask->maxrate)
-		target_rate = mask->maxrate / 100;
-	else
-		return 0;
 
-	for (i = 0; i< sband->n_bitrates; i++) {
-		if (target_rate != sband->bitrates[i].bitrate)
-			continue;
+	for (i = 0; i < IEEE80211_NUM_BANDS; i++)
+		sdata->rc_rateidx_mask[i] = mask->control[i].legacy;
 
-		/* requested bitrate found */
-		sdata->max_ratectrl_rateidx = i;
-		if (mask->fixed)
-			sdata->force_unicast_rateidx = i;
 	return 0;
-	}
-
-	return -EINVAL;
 }
 
 static int ieee80211_remain_on_channel(struct wiphy *wiphy,

net/mac80211/debugfs_netdev.c

@@ -127,8 +127,10 @@ __IEEE80211_IF_FILE(name, ieee80211_if_write_##name)
 
 /* common attributes */
 IEEE80211_IF_FILE(drop_unencrypted, drop_unencrypted, DEC);
-IEEE80211_IF_FILE(force_unicast_rateidx, force_unicast_rateidx, DEC);
-IEEE80211_IF_FILE(max_ratectrl_rateidx, max_ratectrl_rateidx, DEC);
+IEEE80211_IF_FILE(rc_rateidx_mask_2ghz, rc_rateidx_mask[IEEE80211_BAND_2GHZ],
+		  HEX);
+IEEE80211_IF_FILE(rc_rateidx_mask_5ghz, rc_rateidx_mask[IEEE80211_BAND_5GHZ],
+		  HEX);
 
 /* STA attributes */
 IEEE80211_IF_FILE(bssid, u.mgd.bssid, MAC);
@@ -264,8 +266,8 @@ IEEE80211_IF_FILE(dot11MeshHWMPRootMode,
 static void add_sta_files(struct ieee80211_sub_if_data *sdata)
 {
 	DEBUGFS_ADD(drop_unencrypted, sta);
-	DEBUGFS_ADD(force_unicast_rateidx, sta);
-	DEBUGFS_ADD(max_ratectrl_rateidx, sta);
+	DEBUGFS_ADD(rc_rateidx_mask_2ghz, sta);
+	DEBUGFS_ADD(rc_rateidx_mask_5ghz, sta);
 
 	DEBUGFS_ADD(bssid, sta);
 	DEBUGFS_ADD(aid, sta);
@@ -275,8 +277,8 @@ static void add_sta_files(struct ieee80211_sub_if_data *sdata)
 static void add_ap_files(struct ieee80211_sub_if_data *sdata)
 {
 	DEBUGFS_ADD(drop_unencrypted, ap);
-	DEBUGFS_ADD(force_unicast_rateidx, ap);
-	DEBUGFS_ADD(max_ratectrl_rateidx, ap);
+	DEBUGFS_ADD(rc_rateidx_mask_2ghz, ap);
+	DEBUGFS_ADD(rc_rateidx_mask_5ghz, ap);
 
 	DEBUGFS_ADD(num_sta_ps, ap);
 	DEBUGFS_ADD(dtim_count, ap);
@@ -286,8 +288,8 @@ static void add_ap_files(struct ieee80211_sub_if_data *sdata)
 static void add_wds_files(struct ieee80211_sub_if_data *sdata)
 {
 	DEBUGFS_ADD(drop_unencrypted, wds);
-	DEBUGFS_ADD(force_unicast_rateidx, wds);
-	DEBUGFS_ADD(max_ratectrl_rateidx, wds);
+	DEBUGFS_ADD(rc_rateidx_mask_2ghz, wds);
+	DEBUGFS_ADD(rc_rateidx_mask_5ghz, wds);
 
 	DEBUGFS_ADD(peer, wds);
 }
@@ -295,8 +297,8 @@ static void add_wds_files(struct ieee80211_sub_if_data *sdata)
 static void add_vlan_files(struct ieee80211_sub_if_data *sdata)
 {
 	DEBUGFS_ADD(drop_unencrypted, vlan);
-	DEBUGFS_ADD(force_unicast_rateidx, vlan);
-	DEBUGFS_ADD(max_ratectrl_rateidx, vlan);
+	DEBUGFS_ADD(rc_rateidx_mask_2ghz, vlan);
+	DEBUGFS_ADD(rc_rateidx_mask_5ghz, vlan);
 }
 
 static void add_monitor_files(struct ieee80211_sub_if_data *sdata)

net/mac80211/ieee80211_i.h

@@ -494,8 +494,8 @@ struct ieee80211_sub_if_data {
 	 */
 	struct ieee80211_if_ap *bss;
 
-	int force_unicast_rateidx; /* forced TX rateidx for unicast frames */
-	int max_ratectrl_rateidx; /* max TX rateidx for rate control */
+	/* bitmap of allowed (non-MCS) rate indexes for rate control */
+	u32 rc_rateidx_mask[IEEE80211_NUM_BANDS];
 
 	union {
 		struct ieee80211_if_ap ap;

net/mac80211/iface.c

@@ -856,8 +856,12 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 
 	INIT_LIST_HEAD(&sdata->key_list);
 
-	sdata->force_unicast_rateidx = -1;
-	sdata->max_ratectrl_rateidx = -1;
+	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
+		struct ieee80211_supported_band *sband;
+		sband = local->hw.wiphy->bands[i];
+		sdata->rc_rateidx_mask[i] =
+			sband ? (1 << sband->n_bitrates) - 1 : 0;
+	}
 
 	/* setup type-dependent data */
 	ieee80211_setup_sdata(sdata, type);

net/mac80211/rate.c

@@ -249,6 +249,38 @@ bool rate_control_send_low(struct ieee80211_sta *sta,
 }
 EXPORT_SYMBOL(rate_control_send_low);
 
+static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
+				int n_bitrates, u32 mask)
+{
+	int j;
+
+	/* See whether the selected rate or anything below it is allowed. */
+	for (j = rate->idx; j >= 0; j--) {
+		if (mask & (1 << j)) {
+			/* Okay, found a suitable rate. Use it. */
+			rate->idx = j;
+			return;
+		}
+	}
+
+	/* Try to find a higher rate that would be allowed */
+	for (j = rate->idx + 1; j < n_bitrates; j++) {
+		if (mask & (1 << j)) {
+			/* Okay, found a suitable rate. Use it. */
+			rate->idx = j;
+			return;
+		}
+	}
+
+	/*
+	 * Uh.. No suitable rate exists. This should not really happen with
+	 * sane TX rate mask configurations. However, should someone manage to
+	 * configure supported rates and TX rate mask in incompatible way,
+	 * allow the frame to be transmitted with whatever the rate control
+	 * selected.
+	 */
+}
+
 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 			   struct sta_info *sta,
 			   struct ieee80211_tx_rate_control *txrc)
@@ -258,6 +290,7 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_sta *ista = NULL;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 	int i;
+	u32 mask;
 
 	if (sta) {
 		ista = &sta->sta;
@@ -270,23 +303,31 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 		info->control.rates[i].count = 1;
 	}
 
-	if (sta && sdata->force_unicast_rateidx > -1) {
-		info->control.rates[0].idx = sdata->force_unicast_rateidx;
-	} else {
 	ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
-		info->flags |= IEEE80211_TX_INTFL_RCALGO;
-	}
 
 	/*
-	 * try to enforce the maximum rate the user wanted
+	 * Try to enforce the rateidx mask the user wanted. skip this if the
+	 * default mask (allow all rates) is used to save some processing for
+	 * the common case.
+	 */
+	mask = sdata->rc_rateidx_mask[info->band];
+	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
+		if (sta) {
+			/* Filter out rates that the STA does not support */
+			mask &= sta->sta.supp_rates[info->band];
+		}
+		/*
+		 * Make sure the rate index selected for each TX rate is
+		 * included in the configured mask and change the rate indexes
+		 * if needed.
 		 */
-	if (sdata->max_ratectrl_rateidx > -1)
 		for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
+			/* Rate masking supports only legacy rates for now */
 			if (info->control.rates[i].flags & IEEE80211_TX_RC_MCS)
 				continue;
-			info->control.rates[i].idx =
-				min_t(s8, info->control.rates[i].idx,
-				      sdata->max_ratectrl_rateidx);
+			rate_idx_match_mask(&info->control.rates[i],
+					    txrc->sband->n_bitrates, mask);
+		}
 	}
 
 	BUG_ON(info->control.rates[0].idx < 0);

net/mac80211/rate.h

@@ -44,9 +44,6 @@ static inline void rate_control_tx_status(struct ieee80211_local *local,
 	struct rate_control_ref *ref = local->rate_ctrl;
 	struct ieee80211_sta *ista = &sta->sta;
 	void *priv_sta = sta->rate_ctrl_priv;
-	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-
-	if (likely(info->flags & IEEE80211_TX_INTFL_RCALGO))
 	ref->ops->tx_status(ref->priv, sband, ista, priv_sta, skb);
 }
 

net/mac80211/tx.c

@@ -519,7 +519,11 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 	txrc.bss_conf = &tx->sdata->vif.bss_conf;
 	txrc.skb = tx->skb;
 	txrc.reported_rate.idx = -1;
-	txrc.max_rate_idx = tx->sdata->max_ratectrl_rateidx;
+	txrc.rate_idx_mask = tx->sdata->rc_rateidx_mask[tx->channel->band];
+	if (txrc.rate_idx_mask == (1 << sband->n_bitrates) - 1)
+		txrc.max_rate_idx = -1;
+	else
+		txrc.max_rate_idx = fls(txrc.rate_idx_mask) - 1;
 	txrc.ap = tx->sdata->vif.type == NL80211_IFTYPE_AP;
 
 	/* set up RTS protection if desired */
@@ -2178,7 +2182,11 @@ struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 	txrc.bss_conf = &sdata->vif.bss_conf;
 	txrc.skb = skb;
 	txrc.reported_rate.idx = -1;
-	txrc.max_rate_idx = sdata->max_ratectrl_rateidx;
+	txrc.rate_idx_mask = sdata->rc_rateidx_mask[band];
+	if (txrc.rate_idx_mask == (1 << sband->n_bitrates) - 1)
+		txrc.max_rate_idx = -1;
+	else
+		txrc.max_rate_idx = fls(txrc.rate_idx_mask) - 1;
 	txrc.ap = true;
 	rate_control_get_rate(sdata, NULL, &txrc);
 

net/wireless/wext-compat.c

@@ -1204,20 +1204,46 @@ int cfg80211_wext_siwrate(struct net_device *dev,
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_registered_device *rdev = wiphy_to_dev(wdev->wiphy);
 	struct cfg80211_bitrate_mask mask;
+	u32 fixed, maxrate;
+	struct ieee80211_supported_band *sband;
+	int band, ridx;
+	bool match = false;
 
 	if (!rdev->ops->set_bitrate_mask)
 		return -EOPNOTSUPP;
 
-	mask.fixed = 0;
-	mask.maxrate = 0;
+	memset(&mask, 0, sizeof(mask));
+	fixed = 0;
+	maxrate = 0;
 
 	if (rate->value < 0) {
 		/* nothing */
 	} else if (rate->fixed) {
-		mask.fixed = rate->value / 1000; /* kbps */
+		fixed = rate->value / 100000;
 	} else {
-		mask.maxrate = rate->value / 1000; /* kbps */
+		maxrate = rate->value / 100000;
+	}
+
+	for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
+		sband = wdev->wiphy->bands[band];
+		if (sband == NULL)
+			continue;
+		for (ridx = 0; ridx < sband->n_bitrates; ridx++) {
+			struct ieee80211_rate *srate = &sband->bitrates[ridx];
+			if (fixed == srate->bitrate) {
+				mask.control[band].legacy = 1 << ridx;
+				match = true;
+				break;
 			}
+			if (srate->bitrate <= maxrate) {
+				mask.control[band].legacy |= 1 << ridx;
+				match = true;
+			}
+		}
+	}
+
+	if (!match)
+		return -EINVAL;
 
 	return rdev->ops->set_bitrate_mask(wdev->wiphy, dev, NULL, &mask);
 }