On Fri, May 26, 2023 at 12:27:51PM -0400, Mathieu Desnoyers wrote:
> On 5/26/23 12:25, Greg KH wrote:
> > On Fri, May 26, 2023 at 05:05:51PM +0200, Peter Zijlstra wrote:
> > > Convert kernel/sched/core.c to use the fancy new guards to simplify
> > > the error paths.
> >
> > That's slightly crazy...
> >
> > I like the idea, but is this really correct:
> >
> >
> > >
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > ---
> > > kernel/sched/core.c | 1223 +++++++++++++++++++++++----------------------------
> > > kernel/sched/sched.h | 39 +
> > > 2 files changed, 595 insertions(+), 667 deletions(-)
> > >
> > > --- a/kernel/sched/core.c
> > > +++ b/kernel/sched/core.c
> > > @@ -1097,24 +1097,21 @@ int get_nohz_timer_target(void)
> > > hk_mask = housekeeping_cpumask(HK_TYPE_TIMER);
> > > - rcu_read_lock();
> > > - for_each_domain(cpu, sd) {
> > > - for_each_cpu_and(i, sched_domain_span(sd), hk_mask) {
> > > - if (cpu == i)
> > > - continue;
> > > + void_scope(rcu) {
> > > + for_each_domain(cpu, sd) {
> > > + for_each_cpu_and(i, sched_domain_span(sd), hk_mask) {
> > > + if (cpu == i)
> > > + continue;
> > > - if (!idle_cpu(i)) {
> > > - cpu = i;
> > > - goto unlock;
> > > + if (!idle_cpu(i))
> > > + return i;
> >
> > You can call return from within a "scope" and it will clean up properly?
> >
> > I tried to read the cpp "mess" but couldn't figure out how to validate
> > this at all, have a set of tests for this somewhere?
> >
> > Anyway, the naming is whack, but I don't have a proposed better name,
> > except you might want to put "scope_" as the prefix not the suffix, but
> > then that might look odd to, so who knows.
>
> FWIW C++ has std::scoped_lock. So perhaps using a similar wording may help ?
Yeah, I like "scoped_*" and "guarded_*" for naming. IMO, it reads better.
--
Kees Cook
