mac80211: fix and optimize MCS mask handling

Currently the code always copies the configured MCS mask (even if it is
set to default), but only uses it if legacy rates were also masked out.
Fix this by adding a flag that tracks whether the configured MCS mask is
set to default or not.
Optimize the code further by storing a pointer to the configured rate
mask in txrc instead of using memcpy.

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

4 files changed, 26 insertions, 8 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index fdd95bd751a1..72ab1c0e3ca7 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2417,9 +2417,22 @@ static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
 	}
 
 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
+		struct ieee80211_supported_band *sband = wiphy->bands[i];
+		int j;
+
 		sdata->rc_rateidx_mask[i] = mask->control[i].legacy;
 		memcpy(sdata->rc_rateidx_mcs_mask[i], mask->control[i].mcs,
 		       sizeof(mask->control[i].mcs));
+
+		sdata->rc_has_mcs_mask[i] = false;
+		if (!sband)
+			continue;
+
+		for (j = 0; j < IEEE80211_HT_MCS_MASK_LEN; j++)
+			if (~sdata->rc_rateidx_mcs_mask[i][j]) {
+				sdata->rc_has_mcs_mask[i] = true;
+				break;
+			}
 	}
 
 	return 0;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index f4a65a340a52..21c1720eee00 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -739,6 +739,8 @@ struct ieee80211_sub_if_data {
 
 	/* bitmap of allowed (non-MCS) rate indexes for rate control */
 	u32 rc_rateidx_mask[IEEE80211_NUM_BANDS];
+
+	bool rc_has_mcs_mask[IEEE80211_NUM_BANDS];
 	u8  rc_rateidx_mcs_mask[IEEE80211_NUM_BANDS][IEEE80211_HT_MCS_MASK_LEN];
 
 	union {
diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index dd88381c53b7..5d545dd2d050 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -460,9 +460,12 @@ void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
 	 * the common case.
 	 */
 	mask = sdata->rc_rateidx_mask[info->band];
-	memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[info->band],
-	       sizeof(mcs_mask));
-	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
+	if (mask != (1 << txrc->sband->n_bitrates) - 1 || txrc->rate_idx_mcs_mask) {
+		if (txrc->rate_idx_mcs_mask)
+			memcpy(mcs_mask, txrc->rate_idx_mcs_mask, sizeof(mcs_mask));
+		else
+			memset(mcs_mask, 0xff, sizeof(mcs_mask));
+
 		if (sta) {
 			/* Filter out rates that the STA does not support */
 			mask &= sta->sta.supp_rates[info->band];
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index bb82c873f774..15c1b286e280 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -642,9 +642,11 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
 		txrc.max_rate_idx = -1;
 	else
 		txrc.max_rate_idx = fls(txrc.rate_idx_mask) - 1;
-	memcpy(txrc.rate_idx_mcs_mask,
-	       tx->sdata->rc_rateidx_mcs_mask[info->band],
-	       sizeof(txrc.rate_idx_mcs_mask));
+
+	if (tx->sdata->rc_has_mcs_mask[info->band])
+		txrc.rate_idx_mcs_mask =
+			tx->sdata->rc_rateidx_mcs_mask[info->band];
+
 	txrc.bss = (tx->sdata->vif.type == NL80211_IFTYPE_AP ||
 		    tx->sdata->vif.type == NL80211_IFTYPE_MESH_POINT ||
 		    tx->sdata->vif.type == NL80211_IFTYPE_ADHOC);
@@ -2508,8 +2510,6 @@ struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 		txrc.max_rate_idx = -1;
 	else
 		txrc.max_rate_idx = fls(txrc.rate_idx_mask) - 1;
-	memcpy(txrc.rate_idx_mcs_mask, sdata->rc_rateidx_mcs_mask[band],
-	       sizeof(txrc.rate_idx_mcs_mask));
 	txrc.bss = true;
 	rate_control_get_rate(sdata, NULL, &txrc);