Re: [PATCH] cpufreq: CPPC: Avoid overflow when calculating desired_perf

[Hoan Tran]

Hi Rafael,

On Wed, Sep 14, 2016 at 5:50 PM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> On Wednesday, September 14, 2016 04:08:28 PM Hoan Tran wrote:
>> This patch fixes overflow issue when calculating the desired_perf.
>>
>> Signed-off-by: Hoan Tran <hotran@xxxxxxx>
>> ---
>>  drivers/cpufreq/cppc_cpufreq.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
>> index 894e465..3e0961e 100644
>> --- a/drivers/cpufreq/cppc_cpufreq.c
>> +++ b/drivers/cpufreq/cppc_cpufreq.c
>> @@ -84,7 +84,8 @@ static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
>>
>>       cpu = all_cpu_data[policy->cpu];
>>
>> -     cpu->perf_ctrls.desired_perf = target_freq * policy->max / cppc_dmi_max_khz;
>> +     cpu->perf_ctrls.desired_perf =
>> +             (u64)target_freq * policy->max / cppc_dmi_max_khz;
>>       freqs.old = policy->cur;
>>       freqs.new = target_freq;
>
> That's on top of the CPPC material in linux-next I gather?

Yes, it's on TOP of linux-next.

>
> Which commit does it fix?

This is a fix for ad38677df44b67e0f5b6c4d31e9c2734abde8ed9 (cpufreq:
CPPC: Force reporting values in KHz to fix user space interface)
http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/cpufreq/cppc_cpufreq.c?id=ad38677df44b67e0f5b6c4d31e9c2734abde8ed9

Thanks
Hoan

>
> Thanks,
> Rafael
>