Re: [PATCH 07/33] tty: vt: use _IO() to define ioctl numbers

Greg KH
2025-08-01T07:38:45Z

On Fri, Aug 01, 2025 at 06:47:46AM +0200, Jiri Slaby wrote:
> On 31. 07. 25, 22:58, Nicolas Pitre wrote:
> > On Thu, 31 Jul 2025, Christophe Leroy wrote:
> >
> > >
> > >
> > > Le 31/07/2025 à 16:35, Christophe Leroy a écrit :
> > > > Hi Jiri,
> > > >
> > > > Le 11/06/2025 à 12:02, Jiri Slaby (SUSE) a écrit :
> > > > > _IO*() is the proper way of defining ioctl numbers. All these vt numbers
> > > > > were synthetically built up the same way the _IO() macro does.
> > > > >
> > > > > So instead of implicit hex numbers, use _IO() properly.
> > > > >
> > > > > To not change the pre-existing numbers, use only _IO() (and not _IOR()
> > > > > or _IOW()). The latter would change the numbers indeed.
> > > >
> > > > On powerpc your assumption is wrong, because _IOC_NONE is not 0:
> > > >
> > > > $ git grep _IOC_NONE arch/powerpc/
> > > > arch/powerpc/include/uapi/asm/ioctl.h:#define _IOC_NONE 1U
> > > >
> > > > Therefore the value changes even with _IO(), leading to failure of Xorg as
> > > > reported by Christian.
> > > >
> > >
> > > And is likely an issue on the 4 following architectures:
> > >
> > > $ git grep _IOC_NONE arch/ | grep 1U
> > > arch/alpha/include/uapi/asm/ioctl.h:#define _IOC_NONE 1U
> > > arch/mips/include/uapi/asm/ioctl.h:#define _IOC_NONE 1U
> > > arch/powerpc/include/uapi/asm/ioctl.h:#define _IOC_NONE 1U
> > > arch/sparc/include/uapi/asm/ioctl.h:#define _IOC_NONE 1U
> >
> > IMHO this one patch could simply be reverted and the "old" code let be.
>
> Oh, right -- it's easy to revert (no conflicts).
>
> We could use _IOC(0, 'V', number, 0) directly, but I am not sure, that's
> worth it.

Great, can someone send me a revert?

thanks,

greg k-h