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SubjectRe: [PATCH V2,net-next, 3/3] hv_netvsc: Name NICs based on vmbus offer sequence and use async probe
Date
On Mon, Dec 30, 2019 at 12:13:34PM -0800, Haiyang Zhang wrote:
> The dev_num field in vmbus channel structure is assigned to the first
> available number when the channel is offered. So netvsc driver uses it
> for NIC naming based on channel offer sequence. Now re-enable the async
> probing mode for faster probing.
>
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
> drivers/net/hyperv/netvsc_drv.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index f3f9eb8..39c412f 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -2267,10 +2267,14 @@ static int netvsc_probe(struct hv_device *dev,
> struct net_device_context *net_device_ctx;
> struct netvsc_device_info *device_info = NULL;
> struct netvsc_device *nvdev;
> + char name[IFNAMSIZ];
> int ret = -ENOMEM;
>
> - net = alloc_etherdev_mq(sizeof(struct net_device_context),
> - VRSS_CHANNEL_MAX);
> + snprintf(name, IFNAMSIZ, "eth%d", dev->channel->dev_num);

How is this supposed to work when there are other ethernet device types
on the system, which may claim the same device names?

> + net = alloc_netdev_mqs(sizeof(struct net_device_context), name,
> + NET_NAME_ENUM, ether_setup,
> + VRSS_CHANNEL_MAX, VRSS_CHANNEL_MAX);
> +
> if (!net)
> goto no_net;
>
> @@ -2355,6 +2359,14 @@ static int netvsc_probe(struct hv_device *dev,
> net->max_mtu = ETH_DATA_LEN;
>
> ret = register_netdevice(net);
> +
> + if (ret == -EEXIST) {
> + pr_info("NIC name %s exists, request another name.\n",
> + net->name);
> + strlcpy(net->name, "eth%d", IFNAMSIZ);
> + ret = register_netdevice(net);
> + }

IOW you want the device naming to be predictable, but don't guarantee
this?

I think the problem this patchset is trying to solve is much better
solved with a udev rule, similar to how it's done for PCI net devices.
And IMO the primary channel number, being a device's "hardware"
property, is more suited to be used in the device name, than this
completely ephemeral device number.

Thanks,
Roman.

> +
> if (ret != 0) {
> pr_err("Unable to register netdev.\n");
> goto register_failed;
> @@ -2496,7 +2508,7 @@ static int netvsc_resume(struct hv_device *dev)
> .suspend = netvsc_suspend,
> .resume = netvsc_resume,
> .driver = {
> - .probe_type = PROBE_FORCE_SYNCHRONOUS,
> + .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> },
> };
>
> --
> 1.8.3.1
>

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