Re: [PATCH] KVM: selftests: delete some dead code

Peter Xu
2020-06-05T12:48:24Z

On Fri, Jun 05, 2020 at 01:53:16PM +0200, Andrew Jones wrote:
> On Fri, Jun 05, 2020 at 01:16:59PM +0200, Paolo Bonzini wrote:
> > On 05/06/20 13:00, Dan Carpenter wrote:
> > > The "uffd_delay" variable is unsigned so it's always going to be >= 0.
> > >
> > > Fixes: 0119cb365c93 ("KVM: selftests: Add configurable demand paging delay")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > ---
> > > tools/testing/selftests/kvm/demand_paging_test.c | 2 --
> > > 1 file changed, 2 deletions(-)
> > >
> > > diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> > > index 360cd3ea4cd67..4eb79621434e6 100644
> > > --- a/tools/testing/selftests/kvm/demand_paging_test.c
> > > +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> > > @@ -615,8 +615,6 @@ int main(int argc, char *argv[])
> > > break;
> > > case 'd':
> > > uffd_delay = strtoul(optarg, NULL, 0);
> > > - TEST_ASSERT(uffd_delay >= 0,
> > > - "A negative UFFD delay is not supported.");
> > > break;
> > > case 'b':
> > > vcpu_memory_bytes = parse_size(optarg);
> > >
> >
> > The bug is that strtoul is "impossible" to use correctly.

Could I ask why?

> > The right fix
> > would be to have a replacement for strtoul.
>
> The test needs an upper limit. It obviously doesn't make sense to ever
> want a ULONG_MAX usec delay. What's the maximum number of usecs we should
> allow?

Maybe this test can also be used to emulate a hang-forever kvm mmu fault due to
some reason we wanted, by specifying an extremely large value here? From that
POV, seems still ok to even keep it unbound as a test...

Thanks,

--
Peter Xu