Re: [PATCH 3/6] firewire: char device interface

[Kristian Høgsberg <krh@redhat.com>]

Christoph Hellwig wrote:
> On Wed, May 02, 2007 at 02:17:26PM +0200, Stefan Richter wrote:
> > +#include <asm/ioctl.h>
> > +#include <asm/types.h>
>
> Always use the <linux/ versions.

Fixed.

> > +struct fw_cdev_get_info {
> > +	/* The version field is just a running serial number.  We
> > +	 * never break backwards compatibility.  Userspace passes in
> > +	 * the version it expects and the kernel passes back the
> > +	 * highest version it can provide.  Even if the structs in
> > +	 * this interface are extended in a later version, the kernel
> > +	 * will not copy back more data than what was present in the
> > +	 * interface version userspace expects. */
> > +	__u32 version;
>
> Please don't even try to build interfaces this complicated.  If your
> current interface needs changes at some point just introduce new ioctls.

Sure, I don't expect a lot of changes anyway, and the few features I know that 
will show up down the road are strictly additions anyway.  I think it makes 
sense to keep the version number there, though, as a way to advertise which 
ioctls are present.

Kristian


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