Re: [PATCH v2 1/2] KVM: selftests: Drop superfluous use of pthread_attr_setaffinity_np()

[Sean Christopherson <seanjc@google.com>]

On Tue, Jul 07, 2026, sashiko-bot@kernel.org wrote:
> > diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
> > index 76fcdd1fd3cb4..a244bf9f701f7 100644
> > --- a/tools/testing/selftests/kvm/steal_time.c
> > +++ b/tools/testing/selftests/kvm/steal_time.c
> 
> [ ... ]
> 
> > @@ -558,7 +555,11 @@ int main(int ac, char **av)
> >  
> >  		/* Steal time from the VCPU. The steal time thread has the same CPU affinity as the VCPUs. */
> >  		run_delay = get_run_delay();
> > -		pthread_create(&thread, &attr, do_steal_time, NULL);
> > +		pthread_create(&thread, NULL, do_steal_time, NULL);
> > +		pthread_getaffinity_np(thread, sizeof(cpuset), &cpuset);
> 
> [Severity: Medium]
> Can this assertion spuriously pass if pthread_getaffinity_np() fails?

Yes, but that "flaw" is "fixed" in the next patch.  All in quotes because IMO
neither scenario is truly problematic.

> Because cpuset is not cleared before calling pthread_getaffinity_np() in
> main(), and the return value isn't checked, cpuset will retain its previous
> value if the call fails. This could happen if the child thread completes
> its execution before pthread_getaffinity_np() is called.

No, because the underlying kernel task is alive until pthread_join().

> Since cpuset was already populated with CPU 0 earlier in main(), the
> TEST_ASSERT would read the stale data and pass even if the thread did not
> inherit the affinity.