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wifi: mt76: fix race condition related to checking tx queue fill status

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When drv_tx calls race against local tx scheduling, the queue fill status checks
can potentially race, leading to dma queue entries being overwritten.
Fix this by deferring packets from drv_tx calls to the tx worker, in order to
ensure that all regular queue tx comes from the same context.

Signed-off-by: Felix Fietkau <[email protected]>
This commit is contained in:
Felix Fietkau
2023-09-11 13:10:34 +02:00
parent bbbac7deee
commit f1e1e67d97
3 changed files with 120 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tx.c
+88 -20
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@@ -329,40 +329,32 @@ void
mt76_tx(struct mt76_phy *phy, struct ieee80211_sta *sta,
struct mt76_wcid *wcid, struct sk_buff *skb)
{
struct mt76_dev *dev = phy->dev;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
struct mt76_queue *q;
int qid = skb_get_queue_mapping(skb);
if (mt76_testmode_enabled(phy)) {
ieee80211_free_txskb(phy->hw, skb);
return;
}
if (WARN_ON(qid >= MT_TXQ_PSD)) {
qid = MT_TXQ_BE;
skb_set_queue_mapping(skb, qid);
}
if ((dev->drv->drv_flags & MT_DRV_HW_MGMT_TXQ) &&
!(info->flags & IEEE80211_TX_CTL_HW_80211_ENCAP) &&
!ieee80211_is_data(hdr->frame_control) &&
!ieee80211_is_bufferable_mmpdu(skb)) {
qid = MT_TXQ_PSD;
}
if (WARN_ON(skb_get_queue_mapping(skb) >= MT_TXQ_PSD))
skb_set_queue_mapping(skb, MT_TXQ_BE);
if (wcid && !(wcid->tx_info & MT_WCID_TX_INFO_SET))
ieee80211_get_tx_rates(info->control.vif, sta, skb,
info->control.rates, 1);
info->hw_queue |= FIELD_PREP(MT_TX_HW_QUEUE_PHY, phy->band_idx);
q = phy->q_tx[qid];
spin_lock_bh(&q->lock);
__mt76_tx_queue_skb(phy, qid, skb, wcid, sta, NULL);
dev->queue_ops->kick(dev, q);
spin_unlock_bh(&q->lock);
spin_lock_bh(&wcid->tx_pending.lock);
__skb_queue_tail(&wcid->tx_pending, skb);
spin_unlock_bh(&wcid->tx_pending.lock);
spin_lock_bh(&phy->tx_lock);
if (list_empty(&wcid->tx_list))
list_add_tail(&wcid->tx_list, &phy->tx_list);
spin_unlock_bh(&phy->tx_lock);
mt76_worker_schedule(&phy->dev->tx_worker);
}
EXPORT_SYMBOL_GPL(mt76_tx);
@@ -593,10 +585,86 @@ void mt76_txq_schedule(struct mt76_phy *phy, enum mt76_txq_id qid)
}
EXPORT_SYMBOL_GPL(mt76_txq_schedule);
static int
mt76_txq_schedule_pending_wcid(struct mt76_phy *phy, struct mt76_wcid *wcid)
{
struct mt76_dev *dev = phy->dev;
struct ieee80211_sta *sta;
struct mt76_queue *q;
struct sk_buff *skb;
int ret = 0;
spin_lock(&wcid->tx_pending.lock);
while ((skb = skb_peek(&wcid->tx_pending)) != NULL) {
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
int qid = skb_get_queue_mapping(skb);
if ((dev->drv->drv_flags & MT_DRV_HW_MGMT_TXQ) &&
!(info->flags & IEEE80211_TX_CTL_HW_80211_ENCAP) &&
!ieee80211_is_data(hdr->frame_control) &&
!ieee80211_is_bufferable_mmpdu(skb))
qid = MT_TXQ_PSD;
q = phy->q_tx[qid];
if (mt76_txq_stopped(q)) {
ret = -1;
break;
}
__skb_unlink(skb, &wcid->tx_pending);
spin_unlock(&wcid->tx_pending.lock);
sta = wcid_to_sta(wcid);
spin_lock(&q->lock);
__mt76_tx_queue_skb(phy, qid, skb, wcid, sta, NULL);
dev->queue_ops->kick(dev, q);
spin_unlock(&q->lock);
spin_lock(&wcid->tx_pending.lock);
}
spin_unlock(&wcid->tx_pending.lock);
return ret;
}
static void mt76_txq_schedule_pending(struct mt76_phy *phy)
{
if (list_empty(&phy->tx_list))
return;
local_bh_disable();
rcu_read_lock();
spin_lock(&phy->tx_lock);
while (!list_empty(&phy->tx_list)) {
struct mt76_wcid *wcid = NULL;
int ret;
wcid = list_first_entry(&phy->tx_list, struct mt76_wcid, tx_list);
list_del_init(&wcid->tx_list);
spin_unlock(&phy->tx_lock);
ret = mt76_txq_schedule_pending_wcid(phy, wcid);
spin_lock(&phy->tx_lock);
if (ret) {
if (list_empty(&wcid->tx_list))
list_add_tail(&wcid->tx_list, &phy->tx_list);
break;
}
}
spin_unlock(&phy->tx_lock);
rcu_read_unlock();
local_bh_enable();
}
void mt76_txq_schedule_all(struct mt76_phy *phy)
{
int i;
mt76_txq_schedule_pending(phy);
for (i = 0; i <= MT_TXQ_BK; i++)
mt76_txq_schedule(phy, i);
}