Re: [RFC PATCH 5/8] qaic: Implement data path

[Jeffrey Hugo]

On 5/14/2020 10:37 AM, Greg KH wrote:
> On Thu, May 14, 2020 at 10:12:03AM -0600, Jeffrey Hugo wrote:
> > On 5/14/2020 9:56 AM, Greg KH wrote:
> > > On Thu, May 14, 2020 at 09:06:53AM -0600, Jeffrey Hugo wrote:
> > > > On 5/14/2020 8:14 AM, Greg KH wrote:
> > > > > On Thu, May 14, 2020 at 08:07:43AM -0600, Jeffrey Hugo wrote:
> > > > > > +struct qaic_execute {
> > > > > > +	__u16		ver;    /* struct version, must be 1 */
> > > > >
> > > > > No need for structures to be versioned.  If you change something, then
> > > > > add a new ioctl if you really needed it.
> > > >
> > > > Huh.  We had thought the botching ioctls document advised having a version,
> > > > but as I double check that document, it infact does not.
> > > >
> > > > Will remove.
> > >
> > > Thanks, you can also remove the "reserved" variables as well as those
> > > will not be needed either.
> >
> > Are you sure?
> >
> > Documentation/process/botching-up-ioctls.rst
> > Starting at Line 38:
> >
> > "Pad the entire struct to a multiple of 64-bits if the structure contains
> > 64-bit types - the structure size will otherwise differ on 32-bit versus
> > 64-bit. Having a different structure size hurts when passing arrays of
> > structures to the kernel, or if the kernel checks the structure size, which
> > e.g. the drm core does."
> >
> > The "reserved" variables seem to be in line with that.
>
> Padding is fine to use, but don't use that as a "I'm reserving this to
> use it for later" type of thing which is how I read the structure
> definitions.  I might be totally wrong, but you should be explicit here.

Ok, I think I see your point.  I'll change them to be more explicit as 
padding.

--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.