wifi: qtnfmac: allocate dummy net_device dynamically

Embedding net_device into structures prohibits the usage of flexible
arrays in the net_device structure. For more details, see the discussion
at [1].

Un-embed the net_device from struct qtnf_bus by converting it
into a pointer. Then use the leverage alloc_netdev() to allocate the
net_device object at qtnf_pcie_probe(). The free of the device occurs at
qtnf_pcie_remove().

[1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240319172634.894327-1-leitao@debian.org

drivers/net/wireless/quantenna/qtnfmac/bus.h

@@ -59,7 +59,7 @@ struct qtnf_bus {
 	struct qtnf_qlink_transport trans;
 	struct qtnf_hw_info hw_info;
 	struct napi_struct mux_napi;
-	struct net_device mux_dev;
+	struct net_device *mux_dev;
 	struct workqueue_struct *workqueue;
 	struct workqueue_struct *hprio_workqueue;
 	struct work_struct fw_work;

drivers/net/wireless/quantenna/qtnfmac/pcie/pcie.c

@@ -372,7 +372,13 @@ static int qtnf_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto error;
 	}
 
-	init_dummy_netdev(&bus->mux_dev);
+	bus->mux_dev = alloc_netdev(0, "dummy", NET_NAME_UNKNOWN,
+				    init_dummy_netdev);
+	if (!bus->mux_dev) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
 	qtnf_pcie_init_irq(pcie_priv, use_msi);
 	pcie_priv->sysctl_bar = sysctl_bar;
 	pcie_priv->dmareg_bar = dmareg_bar;
@@ -381,11 +387,13 @@ static int qtnf_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	ret = pcie_priv->probe_cb(bus, tx_bd_size_param, rx_bd_size_param);
 	if (ret)
-		goto error;
+		goto error_free;
 
 	qtnf_pcie_bringup_fw_async(bus);
 	return 0;
 
+error_free:
+	free_netdev(bus->mux_dev);
 error:
 	destroy_workqueue(pcie_priv->workqueue);
 	pci_set_drvdata(pdev, NULL);
@@ -417,6 +425,7 @@ static void qtnf_pcie_remove(struct pci_dev *dev)
 	netif_napi_del(&bus->mux_napi);
 	destroy_workqueue(priv->workqueue);
 	tasklet_kill(&priv->reclaim_tq);
+	free_netdev(bus->mux_dev);
 
 	qtnf_pcie_free_shm_ipc(priv);
 	qtnf_debugfs_remove(bus);

drivers/net/wireless/quantenna/qtnfmac/pcie/pearl_pcie.c

@@ -761,12 +761,12 @@ static int qtnf_pcie_pearl_rx_poll(struct napi_struct *napi, int budget)
 				napi_gro_receive(napi, skb);
 			} else {
 				pr_debug("drop untagged skb\n");
-				bus->mux_dev.stats.rx_dropped++;
+				bus->mux_dev->stats.rx_dropped++;
 				dev_kfree_skb_any(skb);
 			}
 		} else {
 			if (skb) {
-				bus->mux_dev.stats.rx_dropped++;
+				bus->mux_dev->stats.rx_dropped++;
 				dev_kfree_skb_any(skb);
 			}
 		}
@@ -1146,7 +1146,7 @@ static int qtnf_pcie_pearl_probe(struct qtnf_bus *bus, unsigned int tx_bd_size,
 	}
 
 	tasklet_setup(&ps->base.reclaim_tq, qtnf_pearl_reclaim_tasklet_fn);
-	netif_napi_add_weight(&bus->mux_dev, &bus->mux_napi,
+	netif_napi_add_weight(bus->mux_dev, &bus->mux_napi,
 			      qtnf_pcie_pearl_rx_poll, 10);
 
 	ipc_int.fn = qtnf_pcie_pearl_ipc_gen_ep_int;

drivers/net/wireless/quantenna/qtnfmac/pcie/topaz_pcie.c

@@ -667,12 +667,12 @@ static int qtnf_topaz_rx_poll(struct napi_struct *napi, int budget)
 				netif_receive_skb(skb);
 			} else {
 				pr_debug("drop untagged skb\n");
-				bus->mux_dev.stats.rx_dropped++;
+				bus->mux_dev->stats.rx_dropped++;
 				dev_kfree_skb_any(skb);
 			}
 		} else {
 			if (skb) {
-				bus->mux_dev.stats.rx_dropped++;
+				bus->mux_dev->stats.rx_dropped++;
 				dev_kfree_skb_any(skb);
 			}
 		}
@@ -1159,7 +1159,7 @@ static int qtnf_pcie_topaz_probe(struct qtnf_bus *bus,
 	}
 
 	tasklet_setup(&ts->base.reclaim_tq, qtnf_reclaim_tasklet_fn);
-	netif_napi_add_weight(&bus->mux_dev, &bus->mux_napi,
+	netif_napi_add_weight(bus->mux_dev, &bus->mux_napi,
 			      qtnf_topaz_rx_poll, 10);
 
 	ipc_int.fn = qtnf_topaz_ipc_gen_ep_int;