[PATCH] wifi: mt76: un-embedd netdev from mt76_dev

[PATCH] wifi: mt76: un-embedd netdev from mt76_dev

[Breno Leitao]

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]
Signed-off-by: Breno Leitao <leitao@debian.org>
---

PS: Due to the lack of hardware, this patch was not tested on a real
hardware, unfortunately.

PS2: this is the last driver that is still using embedded netdevices.

 drivers/net/wireless/mediatek/mt76/debugfs.c  |  6 ++--
 drivers/net/wireless/mediatek/mt76/dma.c      | 31 +++++++++++++++----
 drivers/net/wireless/mediatek/mt76/dma.h      |  5 +++
 drivers/net/wireless/mediatek/mt76/mt76.h     |  4 +--
 .../net/wireless/mediatek/mt76/mt7603/dma.c   |  2 +-
 .../net/wireless/mediatek/mt76/mt7615/dma.c   |  6 ++--
 .../net/wireless/mediatek/mt76/mt76x02_mmio.c |  2 +-
 .../net/wireless/mediatek/mt76/mt7915/dma.c   |  2 +-
 .../net/wireless/mediatek/mt76/mt7921/pci.c   |  2 +-
 .../net/wireless/mediatek/mt76/mt7925/pci.c   |  2 +-
 .../net/wireless/mediatek/mt76/mt792x_dma.c   |  2 +-
 .../net/wireless/mediatek/mt76/mt7996/dma.c   |  2 +-
 12 files changed, 45 insertions(+), 21 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/debugfs.c b/drivers/net/wireless/mediatek/mt76/debugfs.c
index ae83be572b94..b6a2746c187d 100644
--- a/drivers/net/wireless/mediatek/mt76/debugfs.c
+++ b/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;
 }
 
diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index f4f88c444e21..bf67b1f2348a 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_from_netdev(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);
diff --git a/drivers/net/wireless/mediatek/mt76/dma.h b/drivers/net/wireless/mediatek/mt76/dma.h
index 1de5a2b20f74..6454a5eca13e 100644
--- a/drivers/net/wireless/mediatek/mt76/dma.h
+++ b/drivers/net/wireless/mediatek/mt76/dma.h
@@ -116,4 +116,9 @@ mt76_dma_should_drop_buf(bool *drop, u32 ctrl, u32 buf1, u32 info)
 	}
 }
 
+static inline struct mt76_dev *mt76_from_netdev(struct net_device *dev)
+{
+	return *(struct mt76_dev **)netdev_priv(dev);
+}
+
 #endif
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 11b9f22ca7f3..15f83b5adac7 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/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];
diff --git a/drivers/net/wireless/mediatek/mt76/mt7603/dma.c b/drivers/net/wireless/mediatek/mt76/mt7603/dma.c
index 14304b063715..ea017f22fff2 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7603/dma.c
+++ b/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);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/dma.c b/drivers/net/wireless/mediatek/mt76/mt7615/dma.c
index e7135b2f1742..966e3d2c295f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/dma.c
+++ b/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 = (struct mt7615_dev *)mt76_from_netdev(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 = (struct mt7615_dev *)mt76_from_netdev(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);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
index e5ad635d3c56..35b7ebc2c9c6 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
+++ b/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);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/dma.c b/drivers/net/wireless/mediatek/mt76/mt7915/dma.c
index 0baa82c8df5a..0c62272fe7d0 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/dma.c
+++ b/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);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
index f768e9389ac6..e75e7b6d3aaf 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
+++ b/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);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
index 07b74d492ce1..577574fb7a1e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
+++ b/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);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_dma.c b/drivers/net/wireless/mediatek/mt76/mt792x_dma.c
index 5cc2d59b774a..45aed1e1b1a6 100644
--- a/drivers/net/wireless/mediatek/mt76/mt792x_dma.c
+++ b/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 = (struct mt792x_dev *)mt76_from_netdev(napi->dev);
 
 	if (!mt76_connac_pm_ref(&dev->mphy, &dev->pm)) {
 		napi_complete(napi);
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/dma.c b/drivers/net/wireless/mediatek/mt76/mt7996/dma.c
index 73e633d0d700..69a7d9b2e38b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/dma.c
+++ b/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);
 
-- 
2.43.0

Re: [PATCH] wifi: mt76: un-embedd netdev from mt76_dev

[Simon Horman]

On Fri, Jun 14, 2024 at 04:52:42AM -0700, Breno Leitao wrote:
> 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]
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
> 
> PS: Due to the lack of hardware, this patch was not tested on a real
> hardware, unfortunately.
> 
> PS2: this is the last driver that is still using embedded netdevices.

...

> diff --git a/drivers/net/wireless/mediatek/mt76/dma.h b/drivers/net/wireless/mediatek/mt76/dma.h
> index 1de5a2b20f74..6454a5eca13e 100644
> --- a/drivers/net/wireless/mediatek/mt76/dma.h
> +++ b/drivers/net/wireless/mediatek/mt76/dma.h
> @@ -116,4 +116,9 @@ mt76_dma_should_drop_buf(bool *drop, u32 ctrl, u32 buf1, u32 info)
>  	}
>  }
>  
> +static inline struct mt76_dev *mt76_from_netdev(struct net_device *dev)
> +{
> +	return *(struct mt76_dev **)netdev_priv(dev);
> +}
> +
>  #endif

Hi Breno,

I agree that the above is correct, but I wonder if somehow it
is nicer to avoid explicit casts and instead take advantage of
implicit casting too and from void *.

Maybe something like this:

static inline struct mt76_dev *mt76_from_netdev(struct net_device *dev)
{
        struct mt76_dev **priv;

        priv = netdev_priv(dev);

        return *priv;
}

Further, some of the callers of mt76_from_netdev() cast the return value to
(struct mt7615_dev *). Which seems a bit awkward seeing as it was very
recently a void * (i.e. netdev_priv() returns void *).

I wonder if something like this makes sense, which I believe would avoid
the need for any callers to cast.

static inline void *mt76_priv(struct net_device *dev)
{
        struct mt76_dev **priv;

        priv = netdev_priv(dev);

        return *priv;
}

Ideas above compile tested only.

Other than the above, which is clearly more about style than substance,
this patch looks good to me.

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH] wifi: mt76: un-embedd netdev from mt76_dev

[Kalle Valo]

Breno Leitao <leitao@debian.org> writes:

> 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]
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>
> PS: Due to the lack of hardware, this patch was not tested on a real
> hardware, unfortunately.
>
> PS2: this is the last driver that is still using embedded netdevices.

Is this patch a dependency to other patches? I'm asking because it will
be _slow_ to get this patch to net-next via wireless trees. If there's
urgency then it's much better to take it directly to net-next (of course
with acks from Felix and Lorenzo).

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH] wifi: mt76: un-embedd netdev from mt76_dev

[Breno Leitao]

Hello Kalle,

On Mon, Jun 17, 2024 at 12:03:49PM +0300, Kalle Valo wrote:
> Breno Leitao <leitao@debian.org> writes:
> 
> > 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]
> > Signed-off-by: Breno Leitao <leitao@debian.org>
> > ---
> >
> > PS: Due to the lack of hardware, this patch was not tested on a real
> > hardware, unfortunately.
> >
> > PS2: this is the last driver that is still using embedded netdevices.
> 
> Is this patch a dependency to other patches? I'm asking because it will
> be _slow_ to get this patch to net-next via wireless trees. If there's
> urgency then it's much better to take it directly to net-next (of course
> with acks from Felix and Lorenzo).

Since this is the last patch for the whole flexible netdev work, I would
prefer to have it through net-next then, so, we finish the whole work
sooner rather than later.

I will prepare a v2 with Simon's suggestion, and I can target net-next.
I am just waiting a bit more to hear from Felix and Lorenzo.

Thanks!

Re: [PATCH] wifi: mt76: un-embedd netdev from mt76_dev

[Kalle Valo]

Breno Leitao <leitao@debian.org> writes:

> Hello Kalle,
>
> On Mon, Jun 17, 2024 at 12:03:49PM +0300, Kalle Valo wrote:
>> Breno Leitao <leitao@debian.org> writes:
>> 
>> > 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]
>> > Signed-off-by: Breno Leitao <leitao@debian.org>
>> > ---
>> >
>> > PS: Due to the lack of hardware, this patch was not tested on a real
>> > hardware, unfortunately.
>> >
>> > PS2: this is the last driver that is still using embedded netdevices.
>> 
>> Is this patch a dependency to other patches? I'm asking because it will
>> be _slow_ to get this patch to net-next via wireless trees. If there's
>> urgency then it's much better to take it directly to net-next (of course
>> with acks from Felix and Lorenzo).
>
> Since this is the last patch for the whole flexible netdev work, I would
> prefer to have it through net-next then, so, we finish the whole work
> sooner rather than later.

Ok, even though I hate dealing with conflicts between trees I still
think it's better to get this directly to net-next. I hate "hurry up!"
emails even more ;)

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches