Re: [PATCH] cpufreq: Disallow ->resolve_freq() for drivers providing ->target_index()

On Thu, Jul 21, 2016 at 11:23 PM, Viresh Kumar viresh.kumar@linaro.org wrote:

The handlers provided by cpufreq core are sufficient for resolving the frequency for drivers providing ->target_index(), as the core already has the frequency table and so ->resolve_freq() isn't required for such platforms.

This patch disallows drivers with ->target_index() callback to use the ->resolve_freq() callback.

Also, it fixes a potential kernel crash for drivers providing ->target() but no ->resolve_freq().

Fixes: e3c062360870 ("cpufreq: add cpufreq_driver_resolve_freq()") Signed-off-by: Viresh Kumar viresh.kumar@linaro.org

---

drivers/cpufreq/cpufreq.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index b696baeb249d..342bbee8d0e1 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -507,12 +507,20 @@ unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy, { target_freq = clamp_val(target_freq, policy->min, policy->max); policy->cached_target_freq = target_freq;

•   if (cpufreq_driver->target_index) {
  

•           int idx;
  

•           idx = cpufreq_frequency_table_target(policy, target_freq,
  

•                                                CPUFREQ_RELATION_L);
  

•           policy->cached_resolved_idx = idx;
  

•           return policy->freq_table[idx].frequency;
  

•   }
  

•   if (cpufreq_driver->resolve_freq)
            return cpufreq_driver->resolve_freq(policy, target_freq);
  

•   policy->cached_resolved_idx =
  

•           cpufreq_frequency_table_target(policy, target_freq,
  

•                                          CPUFREQ_RELATION_L);
  

•   return policy->freq_table[policy->cached_resolved_idx].frequency;
  

•   return UINT_MAX;
  

I think it should just return target_freq in this case or the UINT_MAX will confuse things in schedutil.

Thanks, Rafael