Hi Rafael,
Thanks for having a look at this..
On 23-06-16, 02:28, Rafael J. Wysocki wrote:
> On Tuesday, June 07, 2016 03:55:14 PM Viresh Kumar wrote:
> > +/* Find lowest freq at or above target in a table in ascending order */
> > +static inline int cpufreq_table_find_index_al(struct cpufreq_policy
> > *policy,
> > + unsigned int target_freq)
> > +{
> > + struct cpufreq_frequency_table *table = policy->freq_table;
> > + unsigned int freq;
> > + int i, best = -1;
> > +
> > + for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
> > + freq = table[i].frequency;
> > +
> > + if (freq_is_invalid(policy, freq))
> > + continue;
> > +
> > + if (freq >= target_freq)
> > + return i;
> > +
> > + best = i;
> > + }
> > +
> > + if (best == -1) {
> > + WARN(1, "Invalid frequency table: %d\n", policy->cpu);
>
> After a successful cpufreq_table_validate_and_show() that should be
> impossible,
> shouldn't it?
This shouldn't be possible unless cpufreq_table_validate_and_show() has a bug,
or somehow that routine isn't called.
Though, to catch such bugs, what about WARN_ON(best == -1); ? The WARN() will
have an unlikely() statement as well to optimize it and we can catch the bugs as
well.
Or if you think we should just remove them..
> > +/* Find highest freq at or below target in a table in descending order */
> > +static inline int cpufreq_table_find_index_dh(struct cpufreq_policy
> > *policy,
> > + unsigned int target_freq)
> > +{
> > + struct cpufreq_frequency_table *table = policy->freq_table;
> > + unsigned int freq;
> > + int i, best = -1;
> > +
> > + for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
> > + freq = table[i].frequency;
> > +
> > + if (freq_is_invalid(policy, freq))
> > + continue;
> > +
> > + if (freq <= target_freq)
> > + return i;
> > +
> > + best = i;
> > + }
> > +
> > + if (best == -1) {
> > + WARN(1, "Invalid frequency table: %d\n", policy->cpu);
> > + return -EINVAL;
> > + }
> > +
> > + return best;
> > +}
>
> I still don't see a reason for min/max checking in these routines.
>
> So what is the reason?
These routines are all part of the existing API cpufreq_frequency_table_target()
and that always had these checks. Over that, not all of its callers are ensuring
that the target-freq is clamped before this routine is called. And so we need to
make sure that these routines return a frequency between min/max only.
What do you say ?
--
viresh
