wifi: mt76: un-embedd netdev from mt76_dev

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_devices from struct mt76_dev by converting them
into pointers, and allocating them dynamically. Use the leverage
alloc_netdev_dummy() to allocate the net_device object at
mt76_dma_init().

The free of the device occurs at mt76_dma_cleanup().

Link: https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/ [1]
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20240619105311.3144908-1-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 25 insertions, 6 deletions

diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index f4f88c444e21..5f46d6daeaa7 100644
--- a/drivers/net/wireless/mediatek/mt76/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/dma.c
@@ -916,7 +916,7 @@ int mt76_dma_rx_poll(struct napi_struct *napi, int budget)
 	struct mt76_dev *dev;
 	int qid, done = 0, cur;
 
-	dev = container_of(napi->dev, struct mt76_dev, napi_dev);
+	dev = mt76_priv(napi->dev);
 	qid = napi - dev->napi;
 
 	rcu_read_lock();
@@ -940,18 +940,35 @@ static int
 mt76_dma_init(struct mt76_dev *dev,
 	      int (*poll)(struct napi_struct *napi, int budget))
 {
+	struct mt76_dev **priv;
 	int i;
 
-	init_dummy_netdev(&dev->napi_dev);
-	init_dummy_netdev(&dev->tx_napi_dev);
-	snprintf(dev->napi_dev.name, sizeof(dev->napi_dev.name), "%s",
+	dev->napi_dev = alloc_netdev_dummy(sizeof(struct mt76_dev *));
+	if (!dev->napi_dev)
+		return -ENOMEM;
+
+	/* napi_dev private data points to mt76_dev parent, so, mt76_dev
+	 * can be retrieved given napi_dev
+	 */
+	priv = netdev_priv(dev->napi_dev);
+	*priv = dev;
+
+	dev->tx_napi_dev = alloc_netdev_dummy(sizeof(struct mt76_dev *));
+	if (!dev->tx_napi_dev) {
+		free_netdev(dev->napi_dev);
+		return -ENOMEM;
+	}
+	priv = netdev_priv(dev->tx_napi_dev);
+	*priv = dev;
+
+	snprintf(dev->napi_dev->name, sizeof(dev->napi_dev->name), "%s",
 		 wiphy_name(dev->hw->wiphy));
-	dev->napi_dev.threaded = 1;
+	dev->napi_dev->threaded = 1;
 	init_completion(&dev->mmio.wed_reset);
 	init_completion(&dev->mmio.wed_reset_complete);
 
 	mt76_for_each_q_rx(dev, i) {
-		netif_napi_add(&dev->napi_dev, &dev->napi[i], poll);
+		netif_napi_add(dev->napi_dev, &dev->napi[i], poll);
 		mt76_dma_rx_fill(dev, &dev->q_rx[i], false);
 		napi_enable(&dev->napi[i]);
 	}
@@ -1019,5 +1036,7 @@ void mt76_dma_cleanup(struct mt76_dev *dev)
 
 	mt76_free_pending_txwi(dev);
 	mt76_free_pending_rxwi(dev);
+	free_netdev(dev->napi_dev);
+	free_netdev(dev->tx_napi_dev);
 }
 EXPORT_SYMBOL_GPL(mt76_dma_cleanup);