Re: [net-next v5 04/15] devlink: Support add and delete devlink port

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 15 Dec 2020 01:03:47 -0800 Saeed Mahameed wrote:
> From: Parav Pandit <parav@nvidia.com>
> 
> Extended devlink interface for the user to add and delete port.
> Extend devlink to connect user requests to driver to add/delete
> such port in the device.
> 
> When driver routines are invoked, devlink instance lock is not held.
> This enables driver to perform several devlink objects registration,
> unregistration such as (port, health reporter, resource etc)
> by using existing devlink APIs.
> This also helps to uniformly use the code for port unregistration
> during driver unload and during port deletion initiated by user.
> 
> Examples of add, show and delete commands:
> $ devlink dev eswitch set pci/0000:06:00.0 mode switchdev
> 
> $ devlink port show
> pci/0000:06:00.0/65535: type eth netdev ens2f0np0 flavour physical port 0 splittable false
> 
> $ devlink port add pci/0000:06:00.0 flavour pcisf pfnum 0 sfnum 88
> 
> $ devlink port show pci/0000:06:00.0/32768
> pci/0000:06:00.0/32768: type eth netdev eth0 flavour pcisf controller 0 pfnum 0 sfnum 88 external false splittable false
>   function:
>     hw_addr 00:00:00:00:88:88 state inactive opstate detached
> 
> $ udevadm test-builtin net_id /sys/class/net/eth0
> Load module index
> Parsed configuration file /usr/lib/systemd/network/99-default.link
> Created link configuration context.
> Using default interface naming scheme 'v245'.
> ID_NET_NAMING_SCHEME=v245
> ID_NET_NAME_PATH=enp6s0f0npf0sf88
> ID_NET_NAME_SLOT=ens2f0npf0sf88
> Unload module index
> Unloaded link configuration context.
> 
> Signed-off-by: Parav Pandit <parav@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
> Reviewed-by: Vu Pham <vuhuong@nvidia.com>
> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

> diff --git a/include/net/devlink.h b/include/net/devlink.h
> index 5bd43f0a79a8..f8cff3e402da 100644
> --- a/include/net/devlink.h
> +++ b/include/net/devlink.h
> @@ -153,6 +153,17 @@ struct devlink_port {
>  	struct mutex reporters_lock; /* Protects reporter_list */
>  };
>  
> +struct devlink_port_new_attrs {
> +	enum devlink_port_flavour flavour;
> +	unsigned int port_index;
> +	u32 controller;
> +	u32 sfnum;
> +	u16 pfnum;

Oh. So you had the structure which actually gets stored in memory for
the lifetime of the device in patch 3 mispacked (u32 / u16 / u32 / u8).
But this one with arguments is packed. Please be consistent.

> +	u8 port_index_valid:1,
> +	   controller_valid:1,
> +	   sfnum_valid:1;
> +};
> +
>  struct devlink_sb_pool_info {
>  	enum devlink_sb_pool_type pool_type;
>  	u32 size;
> @@ -1363,6 +1374,34 @@ struct devlink_ops {
>  	int (*port_function_hw_addr_set)(struct devlink *devlink, struct devlink_port *port,
>  					 const u8 *hw_addr, int hw_addr_len,
>  					 struct netlink_ext_ack *extack);
> +	/**
> +	 * @port_new: Port add function.
> +	 *
> +	 * Should be used by device driver to let caller add new port of a
> +	 * specified flavour with optional attributes.

Add a new port of a specified flavor with optional attributes.

> +	 * Driver should return -EOPNOTSUPP if it doesn't support port addition

s/should/must/

> +	 * of a specified flavour or specified attributes. Driver should set
> +	 * extack error message in case of fail to add the port. Devlink core

s/fail to add the port/failure/

> +	 * does not hold a devlink instance lock when this callback is invoked.

Called without holding the devlink instance lock.

> +	 * Driver must ensures synchronization when adding or deleting a port.

s/ensures/ensure/ but really that's pretty obvious from the previous
sentence.

> +	 * Driver must register a port with devlink core.

s/must/is expected to/

Please make sure your comments and documentation are proof read by
someone.

> +static int devlink_nl_cmd_port_new_doit(struct sk_buff *skb,
> +					struct genl_info *info)
> +{
> +	struct netlink_ext_ack *extack = info->extack;
> +	struct devlink_port_new_attrs new_attrs = {};
> +	struct devlink *devlink = info->user_ptr[0];
> +
> +	if (!info->attrs[DEVLINK_ATTR_PORT_FLAVOUR] ||
> +	    !info->attrs[DEVLINK_ATTR_PORT_PCI_PF_NUMBER]) {
> +		NL_SET_ERR_MSG_MOD(extack, "Port flavour or PCI PF are not specified");
> +		return -EINVAL;
> +	}
> +	new_attrs.flavour = nla_get_u16(info->attrs[DEVLINK_ATTR_PORT_FLAVOUR]);
> +	new_attrs.pfnum =
> +		nla_get_u16(info->attrs[DEVLINK_ATTR_PORT_PCI_PF_NUMBER]);
> +
> +	if (info->attrs[DEVLINK_ATTR_PORT_INDEX]) {
> +		new_attrs.port_index =
> +			nla_get_u32(info->attrs[DEVLINK_ATTR_PORT_INDEX]);
> +		new_attrs.port_index_valid = true;
> +	}

This is the desired port index of the new port?
Or the index of the parent port?
Let's make it abundantly clear since its a pass-thru argument for the
driver to interpret.

> +	if (info->attrs[DEVLINK_ATTR_PORT_CONTROLLER_NUMBER]) {
> +		new_attrs.controller =
> +			nla_get_u16(info->attrs[DEVLINK_ATTR_PORT_CONTROLLER_NUMBER]);
> +		new_attrs.controller_valid = true;
> +	}
> +	if (info->attrs[DEVLINK_ATTR_PORT_PCI_SF_NUMBER]) {
> +		new_attrs.sfnum = nla_get_u32(info->attrs[DEVLINK_ATTR_PORT_PCI_SF_NUMBER]);
> +		new_attrs.sfnum_valid = true;
> +	}
> +
> +	if (!devlink->ops->port_new)
> +		return -EOPNOTSUPP;

Why is this check not at the beginning of the function?
Also should there be an extack on it?

> +	return devlink->ops->port_new(devlink, &new_attrs, extack);

This should return the identifier of the created port back to user
space.