Re: [PATCH net-next] IB/hfi1: allocate dummy net_device dynamically

Leon Romanovsky
2024-03-10T10:14:56Z

On Fri, Mar 08, 2024 at 10:29:50AM -0800, Breno Leitao wrote:
> struct net_device shouldn't be embedded into any structure, instead,
> the owner should use the priv space to embed their state into net_device.

Why?

>
> 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 iwl_trans_pcie by converting it
> into a pointer. Then use the leverage alloc_netdev() to allocate the
> net_device object at iwl_trans_pcie_alloc.
>
> The private data of net_device becomes a pointer for the struct
> iwl_trans_pcie, so, it is easy to get back to the iwl_trans_pcie parent
> given the net_device object.
>
> [1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
> drivers/infiniband/hw/hfi1/netdev.h | 2 +-
> drivers/infiniband/hw/hfi1/netdev_rx.c | 9 +++++++--
> 2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/infiniband/hw/hfi1/netdev.h b/drivers/infiniband/hw/hfi1/netdev.h
> index 8aa074670a9c..07c8f77c9181 100644
> --- a/drivers/infiniband/hw/hfi1/netdev.h
> +++ b/drivers/infiniband/hw/hfi1/netdev.h
> @@ -49,7 +49,7 @@ struct hfi1_netdev_rxq {
> * When 0 receive queues will be freed.
> */
> struct hfi1_netdev_rx {
> - struct net_device rx_napi;
> + struct net_device *rx_napi;
> struct hfi1_devdata *dd;
> struct hfi1_netdev_rxq *rxq;
> int num_rx_q;
> diff --git a/drivers/infiniband/hw/hfi1/netdev_rx.c b/drivers/infiniband/hw/hfi1/netdev_rx.c
> index 720d4c85c9c9..5c26a69fa2bb 100644
> --- a/drivers/infiniband/hw/hfi1/netdev_rx.c
> +++ b/drivers/infiniband/hw/hfi1/netdev_rx.c
> @@ -188,7 +188,7 @@ static int hfi1_netdev_rxq_init(struct hfi1_netdev_rx *rx)
> int i;
> int rc;
> struct hfi1_devdata *dd = rx->dd;
> - struct net_device *dev = &rx->rx_napi;
> + struct net_device *dev = rx->rx_napi;
>
> rx->num_rx_q = dd->num_netdev_contexts;
> rx->rxq = kcalloc_node(rx->num_rx_q, sizeof(*rx->rxq),
> @@ -360,7 +360,11 @@ int hfi1_alloc_rx(struct hfi1_devdata *dd)
> if (!rx)
> return -ENOMEM;
> rx->dd = dd;
> - init_dummy_netdev(&rx->rx_napi);
> + rx->rx_napi = alloc_netdev(sizeof(struct iwl_trans_pcie *),
> + "dummy", NET_NAME_UNKNOWN,

Will it create multiple "dummy" netdev in the system? Will all devices
have the same "dummy" name?

> + init_dummy_netdev);
> + if (!rx->rx_napi)
> + return -ENOMEM;

You forgot to release previously allocated "rx" here.

Thanks

>
> xa_init(&rx->dev_tbl);
> atomic_set(&rx->enabled, 0);
> @@ -374,6 +378,7 @@ void hfi1_free_rx(struct hfi1_devdata *dd)
> {
> if (dd->netdev_rx) {
> dd_dev_info(dd, "hfi1 rx freed\n");
> + free_netdev(dd->netdev_rx->rx_napi);
> kfree(dd->netdev_rx);
> dd->netdev_rx = NULL;
> }
> --
> 2.43.0
>