Re: [linux-next:master 12118/12398] kernel/liveupdate/luo_core.c:402 luo_ioctl() warn: unsigned 'nr' is never less than zero.

[Andrew Morton <akpm@linux-foundation.org>]

On Sat, 29 Nov 2025 15:20:51 -0500 Pasha Tatashin <pasha.tatashin@soleen.com> wrote:

> > > >    393  static long luo_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> > > >    394  {
> > > >    395          const struct luo_ioctl_op *op;
> > > >    396          struct luo_ucmd ucmd = {};
> > > >    397          union ucmd_buffer buf;
> > > >    398          unsigned int nr;
> > > >    399          int err;
> > > >    400
> > > >    401          nr = _IOC_NR(cmd);
> > > >  > 402          if (nr < LIVEUPDATE_CMD_BASE ||
> > > >    403              (nr - LIVEUPDATE_CMD_BASE) >= ARRAY_SIZE(luo_ioctl_ops)) {
> > >
> > > This is a false positive. The logic is designed to work generically
> > > for any base, similar to how it is handled in session ioctl and
> > > iommufd ictl. The warning only triggers because LIVEUPDATE_CMD_BASE
> > > happens to be 0 in this specific case.
> >
> > This is a difficult situation.
> >
> > In some cases smatch has found a bug, in other cases it's just being
> > irritating.
> >
> > I think there is value in smatch occasionally finding bugs, and to
> > support that we should try to rearrange false positives so that smatch
> > doesn't report on those.
> >
> > Perhaps there's some way we can do that here, without uglifying things?
> 
> Yes, we can make "unsigned int nr;" signed: "int nr;", should be OK.
> Would you like me to send a fix patch with this change?

Sure, thanks.  It's a bit lame using an inappropriate type but the
world won't end if we do.