Re: [PATCH] PM: EM: Fix uninitialized power in em_create_perf_table
From: Jinjie Ruan
Date: Mon Nov 04 2024 - 04:20:09 EST
On 2024/11/4 17:14, Lukasz Luba wrote:
> Hi Jinjie,
>
> On 11/4/24 09:03, Jinjie Ruan wrote:
>> In em_create_perf_table(), power is uninitialized and passed the pointer
>> to active_power() hook, but the hook function may not assign it and
>> return 0, such as mtk_cpufreq_get_cpu_power(), so the later zero check
>> for
>
> Please fix the driver. I have checked that function. It must return
> -EINVAL when the 'policy' is not found. We cannot progress with power=0.
Thank you very much! It will be also good to fix the driver.
>
>
>> power is not invalid, initialize power to zero to fix it.
>>
>> Cc: stable@xxxxxxxxxxxxxxx
>> Fixes: 7d9895c7fbfc ("PM / EM: introduce em_dev_register_perf_domain
>> function")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
>> ---
>> kernel/power/energy_model.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
>> index 927cc55ba0b3..866a3e9c05b2 100644
>> --- a/kernel/power/energy_model.c
>> +++ b/kernel/power/energy_model.c
>> @@ -344,7 +344,7 @@ static int em_create_perf_table(struct device
>> *dev, struct em_perf_domain *pd,
>> struct em_data_callback *cb,
>> unsigned long flags)
>> {
>> - unsigned long power, freq, prev_freq = 0;
>> + unsigned long power = 0, freq, prev_freq = 0;
>> int nr_states = pd->nr_perf_states;
>> int i, ret;
>>
>
>
> This patch proposal is just a workaround.
>
> When you send a patch to that MTK driver, I can review it for you so
> please add me on CC.
>
> Regards,
> Lukasz
>