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

[Parav Pandit <parav@nvidia.com>]

> From: Jakub Kicinski <kuba@kernel.org>
> Sent: Wednesday, December 16, 2020 5:59 AM
> 
> > +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.
>
Ok. I will change the packing in patch 3.
 
> > +	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/
>
Ack.
 
> > +	 * 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/
> 
Ack.

> > +	 * does not hold a devlink instance lock when this callback is invoked.
> 
> Called without holding the devlink instance lock.
>
Ack.
 
> > +	 * Driver must ensures synchronization when adding or deleting a
> port.
> 
> s/ensures/ensure/ but really that's pretty obvious from the previous
> sentence.
> 
It may be, but this extra clarity helps, so I am going to keep this explicit description.

> > +	 * Driver must register a port with devlink core.
> 
> s/must/is expected to/
>
Ack.
 
> Please make sure your comments and documentation are proof read by
> someone.
> 
Ack.

> > +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?
Yes.
> Let's make it abundantly clear since its a pass-thru argument for the driver to
> interpret.
>
Ok. Will add comment here.
 
> > +	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?
Will move it up.

> Also should there be an extack on it?
> 
Will check, and add if required.
> > +	return devlink->ops->port_new(devlink, &new_attrs, extack);
> 
> This should return the identifier of the created port back to user space.
Ok. Will add.