On Tuesday 25 Aug 2020 at 11:26:18 (+0530), Viresh Kumar wrote: > On 24-08-20, 22:02, Ionela Voinescu wrote: > > The current frequency passed to arch_set_freq_scale() could end up > > being 0, signaling an error in setting a new frequency. Also, if the > > maximum frequency in 0, this will result in a division by 0 error. > > > > Therefore, validate these input values before using them for the > > setting of the frequency scale factor. > > > > Signed-off-by: Ionela Voinescu <ionela.voine...@arm.com> > > Cc: Sudeep Holla <sudeep.ho...@arm.com> > > Cc: Rafael J. Wysocki <r...@rjwysocki.net> > > --- > > drivers/base/arch_topology.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > > index 75f72d684294..1aca82fcceb8 100644 > > --- a/drivers/base/arch_topology.c > > +++ b/drivers/base/arch_topology.c > > @@ -33,6 +33,9 @@ void arch_set_freq_scale(struct cpumask *cpus, unsigned > > long cur_freq, > > unsigned long scale; > > int i; > > > > + if (!cur_freq || !max_freq) > > We should probably use unlikely() here. > > Rafael: Shouldn't this have a WARN_ON_ONCE() as well ? >
I'll add the unlikely() as it's definitely useful. I'm somewhat on the fence about WARN_ON_ONCE() here. Wouldn't it work better in cpufreq_driver_fast_switch()? It would cover scenarios where the default arch_set_freq_scale() is used and flag potential hardware issues with setting frequency that are currently just ignored both here and in sugov_fast_switch(). Thanks, Ionela.
