wifi: iwlwifi: call napi_synchronize() before freeing rx/tx queues

When rx/tx queues are being freed, on a different CPU there could be
still rx flow running. Call napi_synchronize() to prevent such a race.
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Co-developed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://lore.kernel.org/r/20230416154301.5171ee44dcc1.Iff18718540da412e084e7d8266447d40730600ed@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/internal.h

@@ -497,6 +497,7 @@ int iwl_pcie_rx_stop(struct iwl_trans *trans);
 void iwl_pcie_rx_free(struct iwl_trans *trans);
 void iwl_pcie_free_rbs_pool(struct iwl_trans *trans);
 void iwl_pcie_rx_init_rxb_lists(struct iwl_rxq *rxq);
+void iwl_pcie_rx_napi_sync(struct iwl_trans *trans);
 void iwl_pcie_rxq_alloc_rbs(struct iwl_trans *trans, gfp_t priority,
 			    struct iwl_rxq *rxq);
 

drivers/net/wireless/intel/iwlwifi/pcie/rx.c

 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
 /*
- * Copyright (C) 2003-2014, 2018-2022 Intel Corporation
+ * Copyright (C) 2003-2014, 2018-2023 Intel Corporation
  * Copyright (C) 2013-2015 Intel Mobile Communications GmbH
  * Copyright (C) 2016-2017 Intel Deutschland GmbH
  */
@@ -1053,6 +1053,22 @@ static int iwl_pcie_napi_poll_msix(struct napi_struct *napi, int budget)
 	return ret;
 }
 
+void iwl_pcie_rx_napi_sync(struct iwl_trans *trans)
+{
+	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
+	int i;
+
+	if (unlikely(!trans_pcie->rxq))
+		return;
+
+	for (i = 0; i < trans->num_rx_queues; i++) {
+		struct iwl_rxq *rxq = &trans_pcie->rxq[i];
+
+		if (rxq && rxq->napi.poll)
+			napi_synchronize(&rxq->napi);
+	}
+}
+
 static int _iwl_pcie_rx_init(struct iwl_trans *trans)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);

drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c

@@ -156,6 +156,7 @@ void _iwl_trans_pcie_gen2_stop_device(struct iwl_trans *trans)
 	if (test_and_clear_bit(STATUS_DEVICE_ENABLED, &trans->status)) {
 		IWL_DEBUG_INFO(trans,
 			       "DEVICE_ENABLED bit was set and is now cleared\n");
+		iwl_pcie_rx_napi_sync(trans);
 		iwl_txq_gen2_tx_free(trans);
 		iwl_pcie_rx_stop(trans);
 	}

drivers/net/wireless/intel/iwlwifi/pcie/trans.c

@@ -1260,6 +1260,7 @@ static void _iwl_trans_pcie_stop_device(struct iwl_trans *trans)
 	if (test_and_clear_bit(STATUS_DEVICE_ENABLED, &trans->status)) {
 		IWL_DEBUG_INFO(trans,
 			       "DEVICE_ENABLED bit was set and is now cleared\n");
+		iwl_pcie_rx_napi_sync(trans);
 		iwl_pcie_tx_stop(trans);
 		iwl_pcie_rx_stop(trans);