| Message ID | 20181113194123.93313-3-nbd@nbd.name (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | [1/4] mt76: avoid queue/status spinlocks while passing tx status to mac80211 | expand |
On 2018-11-13 20:41, Felix Fietkau wrote: > If there are still pending packets in the tx queue when removing a station, > it could possibly lead to a call to further attempts to pull packets from > the mac80211 tx queue after it has already been removed from the scheduling > list. > Prevent this from happening by calling synchronize_rcu after deleting the > wcid pointer before further cleaning up the tx queues. > To be extra careful, ensure that mtxq->list is always initialized properly. > > Also drop the useless call to mt76x02_mac_wcid_setup, which only re-assigns > the bss index of the wcid entry, but does not help with the cleanup in any > way. I misread the code and the call to mt76x02_mac_wcid_setup matters after all. Will send a v2 of this series with further improvements. - Felix
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c index 850b0f050da5..cd32ef5864b5 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c @@ -214,14 +214,15 @@ int mt76x02_sta_remove(struct ieee80211_hw *hw, struct ieee80211_vif *vif, int idx = msta->wcid.idx; int i; + rcu_assign_pointer(dev->mt76.wcid[idx], NULL); + synchronize_rcu(); + mutex_lock(&dev->mt76.mutex); mt76_tx_status_check(&dev->mt76, &msta->wcid, true); - rcu_assign_pointer(dev->mt76.wcid[idx], NULL); for (i = 0; i < ARRAY_SIZE(sta->txq); i++) mt76_txq_remove(&dev->mt76, sta->txq[i]); mt76x02_mac_wcid_set_drop(dev, idx, true); mt76_wcid_free(dev->mt76.wcid_mask, idx); - mt76x02_mac_wcid_setup(dev, idx, 0, NULL); mutex_unlock(&dev->mt76.mutex); return 0; diff --git a/drivers/net/wireless/mediatek/mt76/tx.c b/drivers/net/wireless/mediatek/mt76/tx.c index e42a24628e4f..f4093dc0e174 100644 --- a/drivers/net/wireless/mediatek/mt76/tx.c +++ b/drivers/net/wireless/mediatek/mt76/tx.c @@ -590,7 +590,7 @@ void mt76_txq_remove(struct mt76_dev *dev, struct ieee80211_txq *txq) spin_lock_bh(&hwq->lock); if (!list_empty(&mtxq->list)) - list_del(&mtxq->list); + list_del_init(&mtxq->list); spin_unlock_bh(&hwq->lock); while ((skb = skb_dequeue(&mtxq->retry_q)) != NULL)
If there are still pending packets in the tx queue when removing a station, it could possibly lead to a call to further attempts to pull packets from the mac80211 tx queue after it has already been removed from the scheduling list. Prevent this from happening by calling synchronize_rcu after deleting the wcid pointer before further cleaning up the tx queues. To be extra careful, ensure that mtxq->list is always initialized properly. Also drop the useless call to mt76x02_mac_wcid_setup, which only re-assigns the bss index of the wcid entry, but does not help with the cleanup in any way. Signed-off-by: Felix Fietkau <nbd@nbd.name> --- drivers/net/wireless/mediatek/mt76/mt76x02_util.c | 5 +++-- drivers/net/wireless/mediatek/mt76/tx.c | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-)