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.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/wireless/mediatek/mt76/debugfs.c

@@ -33,8 +33,8 @@ mt76_napi_threaded_set(void *data, u64 val)
 	if (!mt76_is_mmio(dev))
 		return -EOPNOTSUPP;
 
-	if (dev->napi_dev.threaded != val)
-		return dev_set_threaded(&dev->napi_dev, val);
+	if (dev->napi_dev->threaded != val)
+		return dev_set_threaded(dev->napi_dev, val);
 
 	return 0;
 }
@@ -44,7 +44,7 @@ mt76_napi_threaded_get(void *data, u64 *val)
 {
 	struct mt76_dev *dev = data;
 
-	*val = dev->napi_dev.threaded;
+	*val = dev->napi_dev->threaded;
 	return 0;
 }
 

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);

drivers/net/wireless/mediatek/mt76/dma.h

@@ -116,4 +116,13 @@ mt76_dma_should_drop_buf(bool *drop, u32 ctrl, u32 buf1, u32 info)
 	}
 }
 
+static inline void *mt76_priv(struct net_device *dev)
+{
+	struct mt76_dev **priv;
+
+	priv = netdev_priv(dev);
+
+	return *priv;
+}
+
 #endif

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -831,8 +831,8 @@ struct mt76_dev {
 
 	struct mt76_mcu mcu;
 
-	struct net_device napi_dev;
-	struct net_device tx_napi_dev;
+	struct net_device *napi_dev;
+	struct net_device *tx_napi_dev;
 	spinlock_t rx_lock;
 	struct napi_struct napi[__MT_RXQ_MAX];
 	struct sk_buff_head rx_skb[__MT_RXQ_MAX];

drivers/net/wireless/mediatek/mt76/mt7603/dma.c

@@ -242,7 +242,7 @@ int mt7603_dma_init(struct mt7603_dev *dev)
 	if (ret)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt7603_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);
 

drivers/net/wireless/mediatek/mt76/mt7615/dma.c

@@ -67,7 +67,7 @@ static int mt7615_poll_tx(struct napi_struct *napi, int budget)
 {
 	struct mt7615_dev *dev;
 
-	dev = container_of(napi, struct mt7615_dev, mt76.tx_napi);
+	dev = mt76_priv(napi->dev);
 	if (!mt76_connac_pm_ref(&dev->mphy, &dev->pm)) {
 		napi_complete(napi);
 		queue_work(dev->mt76.wq, &dev->pm.wake_work);
@@ -89,7 +89,7 @@ static int mt7615_poll_rx(struct napi_struct *napi, int budget)
 	struct mt7615_dev *dev;
 	int done;
 
-	dev = container_of(napi->dev, struct mt7615_dev, mt76.napi_dev);
+	dev = mt76_priv(napi->dev);
 
 	if (!mt76_connac_pm_ref(&dev->mphy, &dev->pm)) {
 		napi_complete(napi);
@@ -282,7 +282,7 @@ int mt7615_dma_init(struct mt7615_dev *dev)
 	if (ret < 0)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt7615_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);
 

drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c

@@ -239,7 +239,7 @@ int mt76x02_dma_init(struct mt76x02_dev *dev)
 	if (ret)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt76x02_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);
 

drivers/net/wireless/mediatek/mt76/mt7915/dma.c

@@ -578,7 +578,7 @@ int mt7915_dma_init(struct mt7915_dev *dev, struct mt7915_phy *phy2)
 	if (ret < 0)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt7915_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);
 

drivers/net/wireless/mediatek/mt76/mt7921/pci.c

@@ -219,7 +219,7 @@ static int mt7921_dma_init(struct mt792x_dev *dev)
 	if (ret < 0)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt792x_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);
 

drivers/net/wireless/mediatek/mt76/mt7925/pci.c

@@ -254,7 +254,7 @@ static int mt7925_dma_init(struct mt792x_dev *dev)
 	if (ret < 0)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt792x_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);
 

drivers/net/wireless/mediatek/mt76/mt792x_dma.c

@@ -340,7 +340,7 @@ int mt792x_poll_rx(struct napi_struct *napi, int budget)
 	struct mt792x_dev *dev;
 	int done;
 
-	dev = container_of(napi->dev, struct mt792x_dev, mt76.napi_dev);
+	dev = mt76_priv(napi->dev);
 
 	if (!mt76_connac_pm_ref(&dev->mphy, &dev->pm)) {
 		napi_complete(napi);

drivers/net/wireless/mediatek/mt76/mt7996/dma.c

@@ -641,7 +641,7 @@ int mt7996_dma_init(struct mt7996_dev *dev)
 	if (ret < 0)
 		return ret;
 
-	netif_napi_add_tx(&dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
+	netif_napi_add_tx(dev->mt76.tx_napi_dev, &dev->mt76.tx_napi,
 			  mt7996_poll_tx);
 	napi_enable(&dev->mt76.tx_napi);