cfg80211/mac80211: improve ad-hoc multicast rate handling

- store the multicast rate as an index instead of the rate value
  (reduces cpu overhead in a hotpath)
- validate the rate values (must match a bitrate in at least one sband)

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 12 insertions, 13 deletions

diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index 76de4f8d9327..3d5a2cb835c4 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -211,20 +211,11 @@ static bool rc_no_data_or_no_ack(struct ieee80211_tx_rate_control *txrc)
         return (info->flags & IEEE80211_TX_CTL_NO_ACK) || !ieee80211_is_data(fc);
 }
 
-static void rc_send_low_broadcast(s8 *idx, u32 basic_rates, u32 mcast_rate,
+static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
                                   struct ieee80211_supported_band *sband)
 {
         u8 i;
 
-        if (mcast_rate) {
-                for (i = 0; i < sband->n_bitrates; i++) {
-                        if (sband->bitrates[i].bitrate == mcast_rate) {
-                                *idx = i;
-                                return;
-                        }
-                }
-        }
-
         if (basic_rates == 0)
                 return; /* assume basic rates unknown and accept rate */
         if (*idx < 0)
@@ -247,17 +238,25 @@ bool rate_control_send_low(struct ieee80211_sta *sta,
                            struct ieee80211_tx_rate_control *txrc)
 {
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
+        struct ieee80211_supported_band *sband = txrc->sband;
+        int mcast_rate;
 
         if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
                 info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
                 info->control.rates[0].count =
                         (info->flags & IEEE80211_TX_CTL_NO_ACK) ?
                         1 : txrc->hw->max_rate_tries;
-                if (!sta && txrc->bss)
+                if (!sta && txrc->bss) {
+                        mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
+                        if (mcast_rate > 0) {
+                                info->control.rates[0].idx = mcast_rate - 1;
+                                return true;
+                        }
+
                         rc_send_low_broadcast(&info->control.rates[0].idx,
                                               txrc->bss_conf->basic_rates,
-                                              txrc->bss_conf->mcast_rate,
-                                              txrc->sband);
+                                              sband);
+                }
                 return true;
         }
         return false;