net: ipa: 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 the private struct by converting it
into a pointer. Then use the leverage the new alloc_netdev_dummy()
helper to allocate and initialize dummy devices.

[1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/gsi.c

@@ -1728,10 +1728,10 @@ static int gsi_channel_setup_one(struct gsi *gsi, u32 channel_id)
 	gsi_channel_program(channel, true);
 
 	if (channel->toward_ipa)
-		netif_napi_add_tx(&gsi->dummy_dev, &channel->napi,
+		netif_napi_add_tx(gsi->dummy_dev, &channel->napi,
 				  gsi_channel_poll);
 	else
-		netif_napi_add(&gsi->dummy_dev, &channel->napi,
+		netif_napi_add(gsi->dummy_dev, &channel->napi,
 			       gsi_channel_poll);
 
 	return 0;
@@ -2367,12 +2367,14 @@ int gsi_init(struct gsi *gsi, struct platform_device *pdev,
 	/* GSI uses NAPI on all channels.  Create a dummy network device
 	 * for the channel NAPI contexts to be associated with.
 	 */
-	init_dummy_netdev(&gsi->dummy_dev);
+	gsi->dummy_dev = alloc_netdev_dummy(0);
+	if (!gsi->dummy_dev)
+		return -ENOMEM;
 	init_completion(&gsi->completion);
 
 	ret = gsi_reg_init(gsi, pdev);
 	if (ret)
-		return ret;
+		goto err_reg_exit;
 
 	ret = gsi_irq_init(gsi, pdev);	/* No matching exit required */
 	if (ret)
@@ -2387,6 +2389,7 @@ int gsi_init(struct gsi *gsi, struct platform_device *pdev,
 	return 0;
 
 err_reg_exit:
+	free_netdev(gsi->dummy_dev);
 	gsi_reg_exit(gsi);
 
 	return ret;
@@ -2397,6 +2400,7 @@ void gsi_exit(struct gsi *gsi)
 {
 	mutex_destroy(&gsi->mutex);
 	gsi_channel_exit(gsi);
+	free_netdev(gsi->dummy_dev);
 	gsi_reg_exit(gsi);
 }
 

drivers/net/ipa/gsi.h

@@ -151,7 +151,7 @@ struct gsi {
 	struct mutex mutex;		/* protects commands, programming */
 	struct gsi_channel channel[GSI_CHANNEL_COUNT_MAX];
 	struct gsi_evt_ring evt_ring[GSI_EVT_RING_COUNT_MAX];
-	struct net_device dummy_dev;	/* needed for NAPI */
+	struct net_device *dummy_dev;	/* needed for NAPI */
 };
 
 /**