wifi: wil6210: Do not use embedded netdev in wil6210_priv

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 wil6210_priv by converting it
into a pointer. Then use the leverage alloc_netdev_dummy() to allocate
the net_device object at wil_if_add(). The free of the device
occurs at wil_if_remove().

Link: https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/ [1]
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240503103304.339489-1-leitao@debian.org

drivers/net/wireless/ath/wil6210/netdev.c

@@ -453,16 +453,21 @@ int wil_if_add(struct wil6210_priv *wil)
 		return rc;
 	}
 
-	init_dummy_netdev(&wil->napi_ndev);
+	wil->napi_ndev = alloc_netdev_dummy(0);
+	if (!wil->napi_ndev) {
+		wil_err(wil, "failed to allocate dummy netdev");
+		rc = -ENOMEM;
+		goto out_wiphy;
+	}
 	if (wil->use_enhanced_dma_hw) {
-		netif_napi_add(&wil->napi_ndev, &wil->napi_rx,
+		netif_napi_add(wil->napi_ndev, &wil->napi_rx,
 			       wil6210_netdev_poll_rx_edma);
-		netif_napi_add_tx(&wil->napi_ndev,
+		netif_napi_add_tx(wil->napi_ndev,
 				  &wil->napi_tx, wil6210_netdev_poll_tx_edma);
 	} else {
-		netif_napi_add(&wil->napi_ndev, &wil->napi_rx,
+		netif_napi_add(wil->napi_ndev, &wil->napi_rx,
 			       wil6210_netdev_poll_rx);
-		netif_napi_add_tx(&wil->napi_ndev,
+		netif_napi_add_tx(wil->napi_ndev,
 				  &wil->napi_tx, wil6210_netdev_poll_tx);
 	}
 
@@ -474,10 +479,12 @@ int wil_if_add(struct wil6210_priv *wil)
 	wiphy_unlock(wiphy);
 	rtnl_unlock();
 	if (rc < 0)
-		goto out_wiphy;
+		goto free_dummy;
 
 	return 0;
 
+free_dummy:
+	free_netdev(wil->napi_ndev);
 out_wiphy:
 	wiphy_unregister(wiphy);
 	return rc;
@@ -554,5 +561,7 @@ void wil_if_remove(struct wil6210_priv *wil)
 	netif_napi_del(&wil->napi_tx);
 	netif_napi_del(&wil->napi_rx);
 
+	free_netdev(wil->napi_ndev);
+
 	wiphy_unregister(wiphy);
 }

drivers/net/wireless/ath/wil6210/wil6210.h

@@ -983,7 +983,7 @@ struct wil6210_priv {
 	spinlock_t eap_lock; /* guarding access to eap rekey fields */
 	struct napi_struct napi_rx;
 	struct napi_struct napi_tx;
-	struct net_device napi_ndev; /* dummy net_device serving all VIFs */
+	struct net_device *napi_ndev; /* dummy net_device serving all VIFs */
 
 	/* DMA related */
 	struct wil_ring ring_rx;