From: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
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 <johannes.berg@xxxxxxxxx>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
---
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();
}
--
1.7.9.5
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