Re: [dm-devel] Re: [RFC] device-mapper ioctl interface
Daniel Phillips (email@example.com)
Mon, 9 Jun 2003 23:39:38 +0200
On Monday 09 June 2003 22:39, Greg KH wrote:
> On Mon, Jun 09, 2003 at 10:03:50PM +0200, Daniel Phillips wrote:
> > On Friday 06 June 2003 19:17, Greg KH wrote:
> > > On Thu, Jun 05, 2003 at 10:39:43AM +0100, Joe Thornber wrote:
> > > > Here's the header file for the the proposed new ioctl interface for
> > > > dm. We've tried to change as little as possible to minimise code
> > > > changes in LVM2 and EVMS.
> > >
> > > Minor comment:
> > > - please do not use uint_32t types in kernel header files. Use
> > > the proper __u32 type which is guarenteed to be the proper
> > > size across the user/kernel boundry.
> > We even have a flavor without the __'s:
> > http://lxr.linux.no/source/include/asm-i386/types.h?v=2.5.56#L47
> > A little easier on the eyes, imho.
> But they are not the same.
> - "__" means this variable will be the same size across the
> kernel/userspace boundry.
> - without the "__" means this variable will only be this size within
> the kernel.
> Use "__" for variables being seen by userspace. Otherwise use the
> types without "__".
Indeed, and (to restate the obvious) ioctl interfaces will need the __ form.
On the other hand, a quick tour through the current tree shows the __ form
being used in a lot more places than it's strictly needed. Although there's
no entry in the style guide for this, perhaps we should consider one.
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