From: Johannes Berg johannes.berg@intel.com
[ Upstream commit 923bf981eb6ecc027227716e30701bdcc1845fbf ]
Some recent upstream debugging uncovered the fact that in iwlwifi, the TXQ list manipulation is racy.
Introduce a new state bit for when the TXQ is completely ready and can be used without locking, and if that's not set yet acquire the lock to check everything correctly.
Reviewed-by: Benjamin Berg benjamin.berg@intel.com Tested-by: Jose Ignacio Tornos Martinez jtornosm@redhat.com Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../net/wireless/intel/iwlwifi/mvm/mac80211.c | 45 ++++++------------- drivers/net/wireless/intel/iwlwifi/mvm/mvm.h | 2 + drivers/net/wireless/intel/iwlwifi/mvm/ops.c | 1 + drivers/net/wireless/intel/iwlwifi/mvm/sta.c | 25 +++++++++-- 4 files changed, 39 insertions(+), 34 deletions(-)
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c index 23e1413ef4719..a841268e0709f 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c @@ -757,42 +757,25 @@ static void iwl_mvm_mac_wake_tx_queue(struct ieee80211_hw *hw, struct iwl_mvm *mvm = IWL_MAC80211_GET_MVM(hw); struct iwl_mvm_txq *mvmtxq = iwl_mvm_txq_from_mac80211(txq);
- /* - * Please note that racing is handled very carefully here: - * mvmtxq->txq_id is updated during allocation, and mvmtxq->list is - * deleted afterwards. - * This means that if: - * mvmtxq->txq_id != INVALID_QUEUE && list_empty(&mvmtxq->list): - * queue is allocated and we can TX. - * mvmtxq->txq_id != INVALID_QUEUE && !list_empty(&mvmtxq->list): - * a race, should defer the frame. - * mvmtxq->txq_id == INVALID_QUEUE && list_empty(&mvmtxq->list): - * need to allocate the queue and defer the frame. - * mvmtxq->txq_id == INVALID_QUEUE && !list_empty(&mvmtxq->list): - * queue is already scheduled for allocation, no need to allocate, - * should defer the frame. - */ - - /* If the queue is allocated TX and return. */ - if (!txq->sta || mvmtxq->txq_id != IWL_MVM_INVALID_QUEUE) { - /* - * Check that list is empty to avoid a race where txq_id is - * already updated, but the queue allocation work wasn't - * finished - */ - if (unlikely(txq->sta && !list_empty(&mvmtxq->list))) - return; - + if (likely(test_bit(IWL_MVM_TXQ_STATE_READY, &mvmtxq->state)) || + !txq->sta) { iwl_mvm_mac_itxq_xmit(hw, txq); return; }
- /* The list is being deleted only after the queue is fully allocated. */ - if (!list_empty(&mvmtxq->list)) - return; + /* iwl_mvm_mac_itxq_xmit() will later be called by the worker + * to handle any packets we leave on the txq now + */
- list_add_tail(&mvmtxq->list, &mvm->add_stream_txqs); - schedule_work(&mvm->add_stream_wk); + spin_lock_bh(&mvm->add_stream_lock); + /* The list is being deleted only after the queue is fully allocated. */ + if (list_empty(&mvmtxq->list) && + /* recheck under lock */ + !test_bit(IWL_MVM_TXQ_STATE_READY, &mvmtxq->state)) { + list_add_tail(&mvmtxq->list, &mvm->add_stream_txqs); + schedule_work(&mvm->add_stream_wk); + } + spin_unlock_bh(&mvm->add_stream_lock); }
#define CHECK_BA_TRIGGER(_mvm, _trig, _tid_bm, _tid, _fmt...) \ diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h b/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h index b5089349ebb7a..f5c921c41be56 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h +++ b/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h @@ -731,6 +731,7 @@ struct iwl_mvm_txq { atomic_t tx_request; #define IWL_MVM_TXQ_STATE_STOP_FULL 0 #define IWL_MVM_TXQ_STATE_STOP_REDIRECT 1 +#define IWL_MVM_TXQ_STATE_READY 2 unsigned long state; };
@@ -829,6 +830,7 @@ struct iwl_mvm { struct iwl_mvm_tvqm_txq_info tvqm_info[IWL_MAX_TVQM_QUEUES]; }; struct work_struct add_stream_wk; /* To add streams to queues */ + spinlock_t add_stream_lock;
const char *nvm_file_name; struct iwl_nvm_data *nvm_data; diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c index 79e151512fe73..994f597a7102a 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c @@ -1184,6 +1184,7 @@ iwl_op_mode_mvm_start(struct iwl_trans *trans, const struct iwl_cfg *cfg, INIT_DELAYED_WORK(&mvm->scan_timeout_dwork, iwl_mvm_scan_timeout_wk); INIT_WORK(&mvm->add_stream_wk, iwl_mvm_add_new_dqa_stream_wk); INIT_LIST_HEAD(&mvm->add_stream_txqs); + spin_lock_init(&mvm->add_stream_lock);
init_waitqueue_head(&mvm->rx_sync_waitq);
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c index 41b1b8b6c1e1d..013aca70c3d3b 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c @@ -383,8 +383,11 @@ static int iwl_mvm_disable_txq(struct iwl_mvm *mvm, struct ieee80211_sta *sta, struct iwl_mvm_txq *mvmtxq = iwl_mvm_txq_from_tid(sta, tid);
- mvmtxq->txq_id = IWL_MVM_INVALID_QUEUE; + spin_lock_bh(&mvm->add_stream_lock); list_del_init(&mvmtxq->list); + clear_bit(IWL_MVM_TXQ_STATE_READY, &mvmtxq->state); + mvmtxq->txq_id = IWL_MVM_INVALID_QUEUE; + spin_unlock_bh(&mvm->add_stream_lock); }
/* Regardless if this is a reserved TXQ for a STA - mark it as false */ @@ -478,8 +481,11 @@ static int iwl_mvm_remove_sta_queue_marking(struct iwl_mvm *mvm, int queue) disable_agg_tids |= BIT(tid); mvmsta->tid_data[tid].txq_id = IWL_MVM_INVALID_QUEUE;
- mvmtxq->txq_id = IWL_MVM_INVALID_QUEUE; + spin_lock_bh(&mvm->add_stream_lock); list_del_init(&mvmtxq->list); + clear_bit(IWL_MVM_TXQ_STATE_READY, &mvmtxq->state); + mvmtxq->txq_id = IWL_MVM_INVALID_QUEUE; + spin_unlock_bh(&mvm->add_stream_lock); }
mvmsta->tfd_queue_msk &= ~BIT(queue); /* Don't use this queue anymore */ @@ -1443,12 +1449,22 @@ void iwl_mvm_add_new_dqa_stream_wk(struct work_struct *wk) * a queue in the function itself. */ if (iwl_mvm_sta_alloc_queue(mvm, txq->sta, txq->ac, tid)) { + spin_lock_bh(&mvm->add_stream_lock); list_del_init(&mvmtxq->list); + spin_unlock_bh(&mvm->add_stream_lock); continue; }
- list_del_init(&mvmtxq->list); + /* now we're ready, any remaining races/concurrency will be + * handled in iwl_mvm_mac_itxq_xmit() + */ + set_bit(IWL_MVM_TXQ_STATE_READY, &mvmtxq->state); + local_bh_disable(); + spin_lock(&mvm->add_stream_lock); + list_del_init(&mvmtxq->list); + spin_unlock(&mvm->add_stream_lock); + iwl_mvm_mac_itxq_xmit(mvm->hw, txq); local_bh_enable(); } @@ -1862,8 +1878,11 @@ static void iwl_mvm_disable_sta_queues(struct iwl_mvm *mvm, struct iwl_mvm_txq *mvmtxq = iwl_mvm_txq_from_mac80211(sta->txq[i]);
+ spin_lock_bh(&mvm->add_stream_lock); mvmtxq->txq_id = IWL_MVM_INVALID_QUEUE; list_del_init(&mvmtxq->list); + clear_bit(IWL_MVM_TXQ_STATE_READY, &mvmtxq->state); + spin_unlock_bh(&mvm->add_stream_lock); } }