Subject: Re: [PATCH 02/39] wimax: declarations for the in-kernel WiMAX API

From: Inaky Perez-Gonzalez <[email-masked]>
Date: Mon, 24 Nov 2008 15:43:33 -0800

On Monday 24 November 2008, Stephen Hemminger wrote:
> On Mon, 24 Nov 2008 13:50:25 -0800
>
> Inaky Perez-Gonzalez <[email-masked]> wrote:
> > [...snip...]
> > + */ 
> > +struct wimax_dev {
> > +	struct net_device *net_dev;
> > +	struct list_head id_table_node;
> > +	struct list_head pipe_list;
> > +	struct wimax_pipe *pipe_msg;
> > +	struct mutex mutex;		/* Protects all members and API calls */
> > +	enum wimax_st state;
> > +
> > +	int (*op_msg_from_user)(struct wimax_dev *wimax_dev,
> > +				const void *, size_t,
> > +				const struct genl_info *info);
> > +	int (*op_rfkill_sw_toggle)(struct wimax_dev *wimax_dev,
> > +				   enum wimax_rf_state);
> > +	int (*op_reset)(struct wimax_dev *wimax_dev);
>
> Move function pointers separate from data??

Most devices will have only a single adapter, so I thought it was not worth 
the overhead of the double dereference when average you will have a single 
copy.

> > +	struct genl_family gnl_family;
>
> Isn't family for all of wimax not per device?

Nope, it is per device. One generic netlink family per device (named "WiMAX 
DEVICENAME"). 

Makes it very easy in user and kernel space, no need for the overhead of 
having an extra attribute for the destination interface.

> > +	struct rfkill *rfkill;
> > +	struct input_dev *rfkill_input;
> > +	unsigned rf_hw:1;
> > +	unsigned rf_sw:1;
>
> don't bother with bitfield overhead make them u8

sure

> > +	char name[32];
> > +};
>
> Why have name in this data structure? Do you handle network device
> renames properly?

This is a physical name, not the network interface name (recommended name in 
the members documentation is DRIVERNAME:physical path.

The reason is it is used to register different things (rfkill device, input 
device for rfkill, threads). It being tied to the physical path makes it easy 
to map and not vulnerable to renames.

Now it might be too short, that's another matter.

-- 
Inaky