From 850bedcc10377629ea88c96c07f8e1d0a99cf4ca Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 25 Feb 2011 12:24:11 +0100 Subject: [PATCH] iwlagn: fix iwlagn_check_needed_chains This function was intended to calculate the number of RX chains needed, but could only work where the AP's streams were asymmetric, i.e. 2 TX and 3 RX or similar. In the case where IEEE80211_HT_MCS_TX_RX_DIFF was not set, this function would calculate the wrong information. Additionally, mac80211 didn't pass through the required values at all, so it couldn't work anyway. Rewrite the logic in this function and add appropriate comments to make it readable. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- drivers/net/wireless/iwlwifi/iwl-agn-rxon.c | 58 +++++++++++++++------ 1 file changed, 41 insertions(+), 17 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c index 6c2adc58d654..dfdbea6e8f99 100644 --- a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c +++ b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c @@ -471,6 +471,7 @@ static void iwlagn_check_needed_chains(struct iwl_priv *priv, struct iwl_rxon_context *tmp; struct ieee80211_sta *sta; struct iwl_ht_config *ht_conf = &priv->current_ht_config; + struct ieee80211_sta_ht_cap *ht_cap; bool need_multiple; lockdep_assert_held(&priv->mutex); @@ -479,23 +480,7 @@ static void iwlagn_check_needed_chains(struct iwl_priv *priv, case NL80211_IFTYPE_STATION: rcu_read_lock(); sta = ieee80211_find_sta(vif, bss_conf->bssid); - if (sta) { - struct ieee80211_sta_ht_cap *ht_cap = &sta->ht_cap; - int maxstreams; - - maxstreams = (ht_cap->mcs.tx_params & - IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK) - >> IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT; - maxstreams += 1; - - need_multiple = true; - - if ((ht_cap->mcs.rx_mask[1] == 0) && - (ht_cap->mcs.rx_mask[2] == 0)) - need_multiple = false; - if (maxstreams <= 1) - need_multiple = false; - } else { + if (!sta) { /* * If at all, this can only happen through a race * when the AP disconnects us while we're still @@ -503,7 +488,46 @@ static void iwlagn_check_needed_chains(struct iwl_priv *priv, * will soon tell us about that. */ need_multiple = false; + rcu_read_unlock(); + break; + } + + ht_cap = &sta->ht_cap; + + need_multiple = true; + + /* + * If the peer advertises no support for receiving 2 and 3 + * stream MCS rates, it can't be transmitting them either. + */ + if (ht_cap->mcs.rx_mask[1] == 0 && + ht_cap->mcs.rx_mask[2] == 0) { + need_multiple = false; + } else if (!(ht_cap->mcs.tx_params & + IEEE80211_HT_MCS_TX_DEFINED)) { + /* If it can't TX MCS at all ... */ + need_multiple = false; + } else if (ht_cap->mcs.tx_params & + IEEE80211_HT_MCS_TX_RX_DIFF) { + int maxstreams; + + /* + * But if it can receive them, it might still not + * be able to transmit them, which is what we need + * to check here -- so check the number of streams + * it advertises for TX (if different from RX). + */ + + maxstreams = (ht_cap->mcs.tx_params & + IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK); + maxstreams >>= + IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT; + maxstreams += 1; + + if (maxstreams <= 1) + need_multiple = false; } + rcu_read_unlock(); break; case NL80211_IFTYPE_ADHOC: -- GitLab