[PATCH net-next] net: wwan: t7xx: Un-embed dummy device

[PATCH net-next] net: wwan: t7xx: Un-embed dummy device

[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_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>
--
PS: This was compile-tested only due to lack of hardware.
---
 drivers/net/wwan/t7xx/t7xx_netdev.c | 20 ++++++++++++++++----
 drivers/net/wwan/t7xx/t7xx_netdev.h |  2 +-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wwan/t7xx/t7xx_netdev.c b/drivers/net/wwan/t7xx/t7xx_netdev.c
index 3ef4a8a4f8fd..91fa082e9cab 100644
--- a/drivers/net/wwan/t7xx/t7xx_netdev.c
+++ b/drivers/net/wwan/t7xx/t7xx_netdev.c
@@ -253,22 +253,27 @@ static void t7xx_ccmni_wwan_setup(struct net_device *dev)
 	dev->netdev_ops = &ccmni_netdev_ops;
 }
 
-static void t7xx_init_netdev_napi(struct t7xx_ccmni_ctrl *ctlb)
+static int t7xx_init_netdev_napi(struct t7xx_ccmni_ctrl *ctlb)
 {
 	int i;
 
 	/* one HW, but shared with multiple net devices,
 	 * so add a dummy device for NAPI.
 	 */
-	init_dummy_netdev(&ctlb->dummy_dev);
+	ctlb->dummy_dev = alloc_netdev_dummy(0);
+	if (!ctlb->dummy_dev)
+		return -ENOMEM;
+
 	atomic_set(&ctlb->napi_usr_refcnt, 0);
 	ctlb->is_napi_en = false;
 
 	for (i = 0; i < RXQ_NUM; i++) {
 		ctlb->napi[i] = &ctlb->hif_ctrl->rxq[i].napi;
-		netif_napi_add_weight(&ctlb->dummy_dev, ctlb->napi[i], t7xx_dpmaif_napi_rx_poll,
+		netif_napi_add_weight(ctlb->dummy_dev, ctlb->napi[i], t7xx_dpmaif_napi_rx_poll,
 				      NIC_NAPI_POLL_BUDGET);
 	}
+
+	return 0;
 }
 
 static void t7xx_uninit_netdev_napi(struct t7xx_ccmni_ctrl *ctlb)
@@ -279,6 +284,7 @@ static void t7xx_uninit_netdev_napi(struct t7xx_ccmni_ctrl *ctlb)
 		netif_napi_del(ctlb->napi[i]);
 		ctlb->napi[i] = NULL;
 	}
+	free_netdev(ctlb->dummy_dev);
 }
 
 static int t7xx_ccmni_wwan_newlink(void *ctxt, struct net_device *dev, u32 if_id,
@@ -480,6 +486,7 @@ int t7xx_ccmni_init(struct t7xx_pci_dev *t7xx_dev)
 {
 	struct device *dev = &t7xx_dev->pdev->dev;
 	struct t7xx_ccmni_ctrl *ctlb;
+	int ret;
 
 	ctlb = devm_kzalloc(dev, sizeof(*ctlb), GFP_KERNEL);
 	if (!ctlb)
@@ -495,7 +502,12 @@ int t7xx_ccmni_init(struct t7xx_pci_dev *t7xx_dev)
 	if (!ctlb->hif_ctrl)
 		return -ENOMEM;
 
-	t7xx_init_netdev_napi(ctlb);
+	ret = t7xx_init_netdev_napi(ctlb);
+	if (ret) {
+		t7xx_dpmaif_hif_exit(ctlb->hif_ctrl);
+		return ret;
+	}
+
 	init_md_status_notifier(t7xx_dev);
 	return 0;
 }
diff --git a/drivers/net/wwan/t7xx/t7xx_netdev.h b/drivers/net/wwan/t7xx/t7xx_netdev.h
index f5ed6f99a145..b18312f49844 100644
--- a/drivers/net/wwan/t7xx/t7xx_netdev.h
+++ b/drivers/net/wwan/t7xx/t7xx_netdev.h
@@ -48,7 +48,7 @@ struct t7xx_ccmni_ctrl {
 	unsigned int			md_sta;
 	struct t7xx_fsm_notifier	md_status_notify;
 	bool				wwan_is_registered;
-	struct net_device		dummy_dev;
+	struct net_device		*dummy_dev;
 	struct napi_struct		*napi[RXQ_NUM];
 	atomic_t			napi_usr_refcnt;
 	bool				is_napi_en;
-- 
2.43.0

Re: [PATCH net-next] net: wwan: t7xx: Un-embed dummy device

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 24 Apr 2024 09:11:07 -0700 you 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_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.
> 
> [...]

Here is the summary with links:
  - [net-next] net: wwan: t7xx: Un-embed dummy device
    https://git.kernel.org/netdev/net-next/c/c984f374aeec

You are awesome, thank you!
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