mac80211: fix a deadlock in minstrel_ht when a HT client without valid MCS rates connects

SVN-Revision: 26287

package/mac80211/patches/580-mac80211_fix_minstrel_ht_crash.patch

@@ -0,0 +1,47 @@
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -659,18 +659,14 @@ minstrel_ht_update_caps(void *priv, stru
+ 	struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
+ 	struct ieee80211_local *local = hw_to_local(mp->hw);
+ 	u16 sta_cap = sta->ht_cap.cap;
++	int n_supported = 0;
+ 	int ack_dur;
+ 	int stbc;
+ 	int i;
+ 
+ 	/* fall back to the old minstrel for legacy stations */
+-	if (!sta->ht_cap.ht_supported) {
+-		msp->is_ht = false;
+-		memset(&msp->legacy, 0, sizeof(msp->legacy));
+-		msp->legacy.r = msp->ratelist;
+-		msp->legacy.sample_table = msp->sample_table;
+-		return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
+-	}
++	if (!sta->ht_cap.ht_supported)
++		goto use_legacy;
+ 
+ 	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
+ 		MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
+@@ -725,7 +721,22 @@ minstrel_ht_update_caps(void *priv, stru
+ 
+ 		mi->groups[i].supported =
+ 			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
++
++		if (mi->groups[i].supported)
++			n_supported++;
+ 	}
++
++	if (!n_supported)
++		goto use_legacy;
++
++	return;
++
++use_legacy:
++	msp->is_ht = false;
++	memset(&msp->legacy, 0, sizeof(msp->legacy));
++	msp->legacy.r = msp->ratelist;
++	msp->legacy.sample_table = msp->sample_table;
++	return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
+ }
+ 
+ static void