Re: [PATCH wireless-next] wifi: ath12k: allocate dummy net_device dynamically

Simon Horman
2024-05-04T14:55:27Z

On Fri, May 03, 2024 at 03:04:39AM -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_device from struct ath12k_ext_irq_grp by converting it
> into a pointer. Then use the leverage alloc_netdev_dummy() to allocate
> the net_device object at ath12k_pci_ext_irq_config().
>
> The free of the device occurs at ath12k_pci_free_ext_irq().
>
> [1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/
>
> This is *very* similar to the same changes in ath11k commit
> bca592ead82528b ("wifi: ath11k: allocate dummy net_device dynamically")
>
> Signed-off-by: Breno Leitao <leitao@debian.org>

...

> diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c

...

> @@ -577,8 +578,11 @@ static int ath12k_pci_ext_irq_config(struct ath12k_base *ab)
>
> irq_grp->ab = ab;
> irq_grp->grp_id = i;
> - init_dummy_netdev(&irq_grp->napi_ndev);
> - netif_napi_add(&irq_grp->napi_ndev, &irq_grp->napi,
> + irq_grp->napi_ndev = alloc_netdev_dummy(0);
> + if (!irq_grp->napi_ndev)
> + return -ENOMEM;

Hi Breno,

Will returning on error here leak resources allocated by
alloc_netdev_dummy() in previous iterations of this loop?

If so, I suggest jumping to unwind handling which
can be shared with the error path in the hunk below.

> +
> + netif_napi_add(irq_grp->napi_ndev, &irq_grp->napi,
> ath12k_pci_ext_grp_napi_poll);
>
> if (ab->hw_params->ring_mask->tx[i] ||
> @@ -611,6 +615,10 @@ static int ath12k_pci_ext_irq_config(struct ath12k_base *ab)
> if (ret) {
> ath12k_err(ab, "failed request irq %d: %d\n",
> vector, ret);
> + for (n = 0; n <= i; n++) {
> + irq_grp = &ab->ext_irq_grp[n];
> + free_netdev(irq_grp->napi_ndev);
> + }
> return ret;
> }
> }

--
pw-client: under-review