From 9bb0c1adc52ca3c7026811a6630a3c78eec1f135 Mon Sep 17 00:00:00 2001 From: Emmanuel Grumbach Date: Mon, 20 Jan 2014 15:21:26 +0200 Subject: [PATCH] iwlwifi: mvm: don't leak a station when we drain We had a bug that prevented us from removing a station after we entered the drain flow: We assign sta to be NULL if it was an error value. Then we tested it against -EBUSY, but forget to retrieve the value again from mvm->fw_id_to_mac_id[sta_id]. Due to this bug, we ended up never removing the STA from the firmware. This led to an firmware assert when we remove the GO vif. Reviewed-by: Johannes Berg Signed-off-by: Emmanuel Grumbach --- drivers/net/wireless/iwlwifi/mvm/tx.c | 73 ++++++++++++++++++----------------- 1 file changed, 37 insertions(+), 36 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/mvm/tx.c b/drivers/net/wireless/iwlwifi/mvm/tx.c index 90378c2..4df12fa 100644 --- a/drivers/net/wireless/iwlwifi/mvm/tx.c +++ b/drivers/net/wireless/iwlwifi/mvm/tx.c @@ -659,8 +659,14 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm, rcu_read_lock(); sta = rcu_dereference(mvm->fw_id_to_mac_id[sta_id]); + /* + * sta can't be NULL otherwise it'd mean that the sta has been freed in + * the firmware while we still have packets for it in the Tx queues. + */ + if (WARN_ON_ONCE(!sta)) + goto out; - if (!IS_ERR_OR_NULL(sta)) { + if (!IS_ERR(sta)) { mvmsta = iwl_mvm_sta_from_mac80211(sta); if (tid != IWL_TID_NON_QOS) { @@ -675,7 +681,6 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm, spin_unlock_bh(&mvmsta->lock); } } else { - sta = NULL; mvmsta = NULL; } @@ -683,42 +688,38 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm, * If the txq is not an AMPDU queue, there is no chance we freed * several skbs. Check that out... */ - if (txq_id < mvm->first_agg_queue && !WARN_ON(skb_freed > 1) && - atomic_sub_and_test(skb_freed, &mvm->pending_frames[sta_id])) { - if (mvmsta) { - /* - * If there are no pending frames for this STA, notify - * mac80211 that this station can go to sleep in its - * STA table. - */ - if (mvmsta->vif->type == NL80211_IFTYPE_AP) - ieee80211_sta_block_awake(mvm->hw, sta, false); - /* - * We might very well have taken mvmsta pointer while - * the station was being removed. The remove flow might - * have seen a pending_frame (because we didn't take - * the lock) even if now the queues are drained. So make - * really sure now that this the station is not being - * removed. If it is, run the drain worker to remove it. - */ - spin_lock_bh(&mvmsta->lock); - sta = rcu_dereference(mvm->fw_id_to_mac_id[sta_id]); - if (!sta || PTR_ERR(sta) == -EBUSY) { - /* - * Station disappeared in the meantime: - * so we are draining. - */ - set_bit(sta_id, mvm->sta_drained); - schedule_work(&mvm->sta_drained_wk); - } - spin_unlock_bh(&mvmsta->lock); - } else if (!mvmsta && PTR_ERR(sta) == -EBUSY) { - /* Tx response without STA, so we are draining */ - set_bit(sta_id, mvm->sta_drained); - schedule_work(&mvm->sta_drained_wk); - } + if (txq_id >= mvm->first_agg_queue) + goto out; + + /* We can't free more than one frame at once on a shared queue */ + WARN_ON(skb_freed > 1); + + /* If we have still frames from this STA nothing to do here */ + if (!atomic_sub_and_test(skb_freed, &mvm->pending_frames[sta_id])) + goto out; + + if (mvmsta && mvmsta->vif->type == NL80211_IFTYPE_AP) { + /* + * If there are no pending frames for this STA, notify + * mac80211 that this station can go to sleep in its + * STA table. + * If mvmsta is not NULL, sta is valid. + */ + ieee80211_sta_block_awake(mvm->hw, sta, false); + } + + if (PTR_ERR(sta) == -EBUSY || PTR_ERR(sta) == -ENOENT) { + /* + * We are draining and this was the last packet - pre_rcu_remove + * has been called already. We might be after the + * synchronize_net already. + * Don't rely on iwl_mvm_rm_sta to see the empty Tx queues. + */ + set_bit(sta_id, mvm->sta_drained); + schedule_work(&mvm->sta_drained_wk); } +out: rcu_read_unlock(); } -- 2.7.4