Re: [RFC v2 09/20] PCI/CMA: Expose in sysfs whether devices are authenticated

[Greg KH]

On Thu, Feb 27, 2025 at 12:52:02PM +0100, Alice Ryhl wrote:
> On Thu, Feb 27, 2025 at 12:17 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Thu, Feb 27, 2025 at 01:09:41PM +1000, Alistair Francis wrote:
> > > +     return rust_authenticated_show(spdm_state, buf);
> >
> > Here you have C code calling into Rust code.  I'm not complaining about
> > it, but I think it will be the first use of this, and I didn't think
> > that the rust maintainers were willing to do that just yet.
> >
> > Has that policy changed?
> >
> > The issue here is that the C signature for this is not being
> > auto-generated, you have to manually keep it in sync (as you did above),
> > with the Rust side.  That's not going to scale over time at all, you
> > MUST have a .h file somewhere for C to know how to call into this and
> > for the compiler to check that all is sane on both sides.
> >
> > And you are passing a random void * into the Rust side, what could go
> > wrong?  I think this needs more thought as this is fragile-as-f***.
> 
> I don't think we have a policy against it? I'm pretty sure the QR code
> thing does it.

Sorry, you are right, it does, and of course it happens (otherwise how
would bindings work), but for small functions like this, how is the C
code kept in sync with the rust side?  Where is the .h file that C
should include?

thanks,

greg "I need more coffee" k-h