Hi Viresh,
One scenario is there where a kernel panic is observed in
cpufreq during suspend/resume.
pm_suspend()
suspend_devices_and_enter()
dpm_suspend_start()
dpm_prepare()
Failure in dpm_prepare() happend with following dmesg:
[ 3746.316062] PM: Device xyz not prepared for power transition: code -16
[ 3746.316071] PM: Some devices failed to suspend, or early wake event detected
pm_suspend()
suspend_devices_and_enter()
dpm_suspend_start()
dpm_prepare() //failed
dpm_resume_end()
dpm_resume()
cpufreq_resume()
cpufreq_start_governor()
sugov_start()
cpufreq_add_update_util_hook()
After failure in dpm_prepare(), dpm_resume() called
cpufreq_resume(). Corresponding cpufreq_suspend() was not
called due to failure of dpm_prepare().
This resulted in WARN_ON(per_cpu(cpufreq_update_util_data, cpu))
in cpufreq_add_update_util_hook() and cpufreq_add_update_util_hook->func
being inconsistent state. It caused crash in scheduler.
Following are some of the ways to mitigate this issue. Could
you please provide feedback on below two approaches or suugest
a better way to fix this problem.
-----------------------8<------------------------------
Co-developed-by: Gaurav Kohli <[email protected]>
Signed-off-by: Gaurav Kohli <[email protected]>
Signed-off-by: Prateek Sood <[email protected]>
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 02a497e..732e5a2 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1038,6 +1038,7 @@ void dpm_resume(pm_message_t state)
{
struct device *dev;
ktime_t starttime = ktime_get();
+ bool valid_resume = false;
trace_suspend_resume(TPS("dpm_resume"), state.event, true);
might_sleep();
@@ -1055,6 +1056,7 @@ void dpm_resume(pm_message_t state)
}
while (!list_empty(&dpm_suspended_list)) {
+ valid_resume = true;
dev = to_device(dpm_suspended_list.next);
get_device(dev);
if (!is_async(dev)) {
@@ -1080,7 +1082,8 @@ void dpm_resume(pm_message_t state)
async_synchronize_full();
dpm_show_time(starttime, state, 0, NULL);
- cpufreq_resume();
+ if (valid_resume)
+ cpufreq_resume();
trace_suspend_resume(TPS("dpm_resume"), state.event, false);
}
--------------------8<--------------------------------------
Signed-off-by: Prateek Sood <[email protected]>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 421f318..439eab8 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1648,7 +1648,7 @@ void cpufreq_suspend(void)
{
struct cpufreq_policy *policy;
- if (!cpufreq_driver)
+ if (!cpufreq_driver || cpufreq_suspended)
return;
if (!has_target() && !cpufreq_driver->suspend)
@@ -1683,7 +1683,7 @@ void cpufreq_resume(void)
struct cpufreq_policy *policy;
int ret;
- if (!cpufreq_driver)
+ if (!cpufreq_driver || !cpufreq_suspended)
return;
cpufreq_suspended = false;
Thanks
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project
On Friday, February 2, 2018 12:41:58 PM CET Prateek Sood wrote:
> Hi Viresh,
>
> One scenario is there where a kernel panic is observed in
> cpufreq during suspend/resume.
>
> pm_suspend()
> suspend_devices_and_enter()
> dpm_suspend_start()
> dpm_prepare()
>
> Failure in dpm_prepare() happend with following dmesg:
>
> [ 3746.316062] PM: Device xyz not prepared for power transition: code -16
> [ 3746.316071] PM: Some devices failed to suspend, or early wake event detected
>
>
> pm_suspend()
> suspend_devices_and_enter()
> dpm_suspend_start()
> dpm_prepare() //failed
> dpm_resume_end()
> dpm_resume()
> cpufreq_resume()
> cpufreq_start_governor()
> sugov_start()
> cpufreq_add_update_util_hook()
>
> After failure in dpm_prepare(), dpm_resume() called
> cpufreq_resume(). Corresponding cpufreq_suspend() was not
> called due to failure of dpm_prepare().
>
> This resulted in WARN_ON(per_cpu(cpufreq_update_util_data, cpu))
> in cpufreq_add_update_util_hook() and cpufreq_add_update_util_hook->func
> being inconsistent state. It caused crash in scheduler.
>
> Following are some of the ways to mitigate this issue. Could
> you please provide feedback on below two approaches or suugest
> a better way to fix this problem.
>
> -----------------------8<------------------------------
>
> Co-developed-by: Gaurav Kohli <[email protected]>
> Signed-off-by: Gaurav Kohli <[email protected]>
> Signed-off-by: Prateek Sood <[email protected]>
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 02a497e..732e5a2 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -1038,6 +1038,7 @@ void dpm_resume(pm_message_t state)
> {
> struct device *dev;
> ktime_t starttime = ktime_get();
> + bool valid_resume = false;
>
> trace_suspend_resume(TPS("dpm_resume"), state.event, true);
> might_sleep();
> @@ -1055,6 +1056,7 @@ void dpm_resume(pm_message_t state)
> }
>
> while (!list_empty(&dpm_suspended_list)) {
> + valid_resume = true;
> dev = to_device(dpm_suspended_list.next);
> get_device(dev);
> if (!is_async(dev)) {
> @@ -1080,7 +1082,8 @@ void dpm_resume(pm_message_t state)
> async_synchronize_full();
> dpm_show_time(starttime, state, 0, NULL);
>
> - cpufreq_resume();
> + if (valid_resume)
> + cpufreq_resume();
> trace_suspend_resume(TPS("dpm_resume"), state.event, false);
> }
>
> --------------------8<--------------------------------------
>
> Signed-off-by: Prateek Sood <[email protected]>
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 421f318..439eab8 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1648,7 +1648,7 @@ void cpufreq_suspend(void)
> {
> struct cpufreq_policy *policy;
>
> - if (!cpufreq_driver)
> + if (!cpufreq_driver || cpufreq_suspended)
> return;
>
> if (!has_target() && !cpufreq_driver->suspend)
> @@ -1683,7 +1683,7 @@ void cpufreq_resume(void)
> struct cpufreq_policy *policy;
> int ret;
>
> - if (!cpufreq_driver)
> + if (!cpufreq_driver || !cpufreq_suspended)
> return;
>
> cpufreq_suspended = false;
Since we have cpufreq_suspended already, the second one is better.
Thanks,
Rafael
On 02/02/2018 05:18 PM, Rafael J. Wysocki wrote:
> On Friday, February 2, 2018 12:41:58 PM CET Prateek Sood wrote:
>> Hi Viresh,
>>
>> One scenario is there where a kernel panic is observed in
>> cpufreq during suspend/resume.
>>
>> pm_suspend()
>> suspend_devices_and_enter()
>> dpm_suspend_start()
>> dpm_prepare()
>>
>> Failure in dpm_prepare() happend with following dmesg:
>>
>> [ 3746.316062] PM: Device xyz not prepared for power transition: code -16
>> [ 3746.316071] PM: Some devices failed to suspend, or early wake event detected
>>
>>
>> pm_suspend()
>> suspend_devices_and_enter()
>> dpm_suspend_start()
>> dpm_prepare() //failed
>> dpm_resume_end()
>> dpm_resume()
>> cpufreq_resume()
>> cpufreq_start_governor()
>> sugov_start()
>> cpufreq_add_update_util_hook()
>>
>> After failure in dpm_prepare(), dpm_resume() called
>> cpufreq_resume(). Corresponding cpufreq_suspend() was not
>> called due to failure of dpm_prepare().
>>
>> This resulted in WARN_ON(per_cpu(cpufreq_update_util_data, cpu))
>> in cpufreq_add_update_util_hook() and cpufreq_add_update_util_hook->func
>> being inconsistent state. It caused crash in scheduler.
>>
>> Following are some of the ways to mitigate this issue. Could
>> you please provide feedback on below two approaches or suugest
>> a better way to fix this problem.
>>
>> -----------------------8<------------------------------
>>
>> Co-developed-by: Gaurav Kohli <[email protected]>
>> Signed-off-by: Gaurav Kohli <[email protected]>
>> Signed-off-by: Prateek Sood <[email protected]>
>>
>> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
>> index 02a497e..732e5a2 100644
>> --- a/drivers/base/power/main.c
>> +++ b/drivers/base/power/main.c
>> @@ -1038,6 +1038,7 @@ void dpm_resume(pm_message_t state)
>> {
>> struct device *dev;
>> ktime_t starttime = ktime_get();
>> + bool valid_resume = false;
>>
>> trace_suspend_resume(TPS("dpm_resume"), state.event, true);
>> might_sleep();
>> @@ -1055,6 +1056,7 @@ void dpm_resume(pm_message_t state)
>> }
>>
>> while (!list_empty(&dpm_suspended_list)) {
>> + valid_resume = true;
>> dev = to_device(dpm_suspended_list.next);
>> get_device(dev);
>> if (!is_async(dev)) {
>> @@ -1080,7 +1082,8 @@ void dpm_resume(pm_message_t state)
>> async_synchronize_full();
>> dpm_show_time(starttime, state, 0, NULL);
>>
>> - cpufreq_resume();
>> + if (valid_resume)
>> + cpufreq_resume();
>> trace_suspend_resume(TPS("dpm_resume"), state.event, false);
>> }
>>
>> --------------------8<--------------------------------------
>>
>> Signed-off-by: Prateek Sood <[email protected]>
>>
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index 421f318..439eab8 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -1648,7 +1648,7 @@ void cpufreq_suspend(void)
>> {
>> struct cpufreq_policy *policy;
>>
>> - if (!cpufreq_driver)
>> + if (!cpufreq_driver || cpufreq_suspended)
>> return;
>>
>> if (!has_target() && !cpufreq_driver->suspend)
>> @@ -1683,7 +1683,7 @@ void cpufreq_resume(void)
>> struct cpufreq_policy *policy;
>> int ret;
>>
>> - if (!cpufreq_driver)
>> + if (!cpufreq_driver || !cpufreq_suspended)
>> return;
>>
>> cpufreq_suspended = false;
>
> Since we have cpufreq_suspended already, the second one is better.
>
> Thanks,
> Rafael
>
Thanks Rafael for the inputs, I will send a formal patch.
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project
On Fri, Feb 2, 2018 at 1:53 PM, Prateek Sood <[email protected]> wrote:
> On 02/02/2018 05:18 PM, Rafael J. Wysocki wrote:
>> On Friday, February 2, 2018 12:41:58 PM CET Prateek Sood wrote:
>>> Hi Viresh,
>>>
>>> One scenario is there where a kernel panic is observed in
>>> cpufreq during suspend/resume.
>>>
>>> pm_suspend()
>>> suspend_devices_and_enter()
>>> dpm_suspend_start()
>>> dpm_prepare()
>>>
>>> Failure in dpm_prepare() happend with following dmesg:
>>>
>>> [ 3746.316062] PM: Device xyz not prepared for power transition: code -16
>>> [ 3746.316071] PM: Some devices failed to suspend, or early wake event detected
>>>
>>>
>>> pm_suspend()
>>> suspend_devices_and_enter()
>>> dpm_suspend_start()
>>> dpm_prepare() //failed
>>> dpm_resume_end()
>>> dpm_resume()
>>> cpufreq_resume()
>>> cpufreq_start_governor()
>>> sugov_start()
>>> cpufreq_add_update_util_hook()
>>>
>>> After failure in dpm_prepare(), dpm_resume() called
>>> cpufreq_resume(). Corresponding cpufreq_suspend() was not
>>> called due to failure of dpm_prepare().
>>>
>>> This resulted in WARN_ON(per_cpu(cpufreq_update_util_data, cpu))
>>> in cpufreq_add_update_util_hook() and cpufreq_add_update_util_hook->func
>>> being inconsistent state. It caused crash in scheduler.
>>>
>>> Following are some of the ways to mitigate this issue. Could
>>> you please provide feedback on below two approaches or suugest
>>> a better way to fix this problem.
>>>
>>> -----------------------8<------------------------------
>>>
>>> Co-developed-by: Gaurav Kohli <[email protected]>
>>> Signed-off-by: Gaurav Kohli <[email protected]>
>>> Signed-off-by: Prateek Sood <[email protected]>
>>>
>>> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
>>> index 02a497e..732e5a2 100644
>>> --- a/drivers/base/power/main.c
>>> +++ b/drivers/base/power/main.c
>>> @@ -1038,6 +1038,7 @@ void dpm_resume(pm_message_t state)
>>> {
>>> struct device *dev;
>>> ktime_t starttime = ktime_get();
>>> + bool valid_resume = false;
>>>
>>> trace_suspend_resume(TPS("dpm_resume"), state.event, true);
>>> might_sleep();
>>> @@ -1055,6 +1056,7 @@ void dpm_resume(pm_message_t state)
>>> }
>>>
>>> while (!list_empty(&dpm_suspended_list)) {
>>> + valid_resume = true;
>>> dev = to_device(dpm_suspended_list.next);
>>> get_device(dev);
>>> if (!is_async(dev)) {
>>> @@ -1080,7 +1082,8 @@ void dpm_resume(pm_message_t state)
>>> async_synchronize_full();
>>> dpm_show_time(starttime, state, 0, NULL);
>>>
>>> - cpufreq_resume();
>>> + if (valid_resume)
>>> + cpufreq_resume();
>>> trace_suspend_resume(TPS("dpm_resume"), state.event, false);
>>> }
>>>
>>> --------------------8<--------------------------------------
>>>
>>> Signed-off-by: Prateek Sood <[email protected]>
>>>
>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>>> index 421f318..439eab8 100644
>>> --- a/drivers/cpufreq/cpufreq.c
>>> +++ b/drivers/cpufreq/cpufreq.c
>>> @@ -1648,7 +1648,7 @@ void cpufreq_suspend(void)
>>> {
>>> struct cpufreq_policy *policy;
>>>
>>> - if (!cpufreq_driver)
>>> + if (!cpufreq_driver || cpufreq_suspended)
>>> return;
>>>
>>> if (!has_target() && !cpufreq_driver->suspend)
>>> @@ -1683,7 +1683,7 @@ void cpufreq_resume(void)
>>> struct cpufreq_policy *policy;
>>> int ret;
>>>
>>> - if (!cpufreq_driver)
>>> + if (!cpufreq_driver || !cpufreq_suspended)
>>> return;
>>>
>>> cpufreq_suspended = false;
>>
>> Since we have cpufreq_suspended already, the second one is better.
>>
>
> Thanks Rafael for the inputs, I will send a formal patch.
Bo Yan has posted something really similar already, however:
https://patchwork.kernel.org/patch/10181101/
so I would prefer to apply a new version of that one with the latest
comment taken into account:
https://patchwork.kernel.org/patch/10183075/
for the credit to go to the first submitter.
On 02/02/2018 06:49 PM, Rafael J. Wysocki wrote:
> On Fri, Feb 2, 2018 at 1:53 PM, Prateek Sood <[email protected]> wrote:
>> On 02/02/2018 05:18 PM, Rafael J. Wysocki wrote:
>>> On Friday, February 2, 2018 12:41:58 PM CET Prateek Sood wrote:
>>>> Hi Viresh,
>>>>
>>>> One scenario is there where a kernel panic is observed in
>>>> cpufreq during suspend/resume.
>>>>
>>>> pm_suspend()
>>>> suspend_devices_and_enter()
>>>> dpm_suspend_start()
>>>> dpm_prepare()
>>>>
>>>> Failure in dpm_prepare() happend with following dmesg:
>>>>
>>>> [ 3746.316062] PM: Device xyz not prepared for power transition: code -16
>>>> [ 3746.316071] PM: Some devices failed to suspend, or early wake event detected
>>>>
>>>>
>>>> pm_suspend()
>>>> suspend_devices_and_enter()
>>>> dpm_suspend_start()
>>>> dpm_prepare() //failed
>>>> dpm_resume_end()
>>>> dpm_resume()
>>>> cpufreq_resume()
>>>> cpufreq_start_governor()
>>>> sugov_start()
>>>> cpufreq_add_update_util_hook()
>>>>
>>>> After failure in dpm_prepare(), dpm_resume() called
>>>> cpufreq_resume(). Corresponding cpufreq_suspend() was not
>>>> called due to failure of dpm_prepare().
>>>>
>>>> This resulted in WARN_ON(per_cpu(cpufreq_update_util_data, cpu))
>>>> in cpufreq_add_update_util_hook() and cpufreq_add_update_util_hook->func
>>>> being inconsistent state. It caused crash in scheduler.
>>>>
>>>> Following are some of the ways to mitigate this issue. Could
>>>> you please provide feedback on below two approaches or suugest
>>>> a better way to fix this problem.
>>>>
>>>> -----------------------8<------------------------------
>>>>
>>>> Co-developed-by: Gaurav Kohli <[email protected]>
>>>> Signed-off-by: Gaurav Kohli <[email protected]>
>>>> Signed-off-by: Prateek Sood <[email protected]>
>>>>
>>>> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
>>>> index 02a497e..732e5a2 100644
>>>> --- a/drivers/base/power/main.c
>>>> +++ b/drivers/base/power/main.c
>>>> @@ -1038,6 +1038,7 @@ void dpm_resume(pm_message_t state)
>>>> {
>>>> struct device *dev;
>>>> ktime_t starttime = ktime_get();
>>>> + bool valid_resume = false;
>>>>
>>>> trace_suspend_resume(TPS("dpm_resume"), state.event, true);
>>>> might_sleep();
>>>> @@ -1055,6 +1056,7 @@ void dpm_resume(pm_message_t state)
>>>> }
>>>>
>>>> while (!list_empty(&dpm_suspended_list)) {
>>>> + valid_resume = true;
>>>> dev = to_device(dpm_suspended_list.next);
>>>> get_device(dev);
>>>> if (!is_async(dev)) {
>>>> @@ -1080,7 +1082,8 @@ void dpm_resume(pm_message_t state)
>>>> async_synchronize_full();
>>>> dpm_show_time(starttime, state, 0, NULL);
>>>>
>>>> - cpufreq_resume();
>>>> + if (valid_resume)
>>>> + cpufreq_resume();
>>>> trace_suspend_resume(TPS("dpm_resume"), state.event, false);
>>>> }
>>>>
>>>> --------------------8<--------------------------------------
>>>>
>>>> Signed-off-by: Prateek Sood <[email protected]>
>>>>
>>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>>>> index 421f318..439eab8 100644
>>>> --- a/drivers/cpufreq/cpufreq.c
>>>> +++ b/drivers/cpufreq/cpufreq.c
>>>> @@ -1648,7 +1648,7 @@ void cpufreq_suspend(void)
>>>> {
>>>> struct cpufreq_policy *policy;
>>>>
>>>> - if (!cpufreq_driver)
>>>> + if (!cpufreq_driver || cpufreq_suspended)
>>>> return;
>>>>
>>>> if (!has_target() && !cpufreq_driver->suspend)
>>>> @@ -1683,7 +1683,7 @@ void cpufreq_resume(void)
>>>> struct cpufreq_policy *policy;
>>>> int ret;
>>>>
>>>> - if (!cpufreq_driver)
>>>> + if (!cpufreq_driver || !cpufreq_suspended)
>>>> return;
>>>>
>>>> cpufreq_suspended = false;
>>>
>>> Since we have cpufreq_suspended already, the second one is better.
>>>
>>
>> Thanks Rafael for the inputs, I will send a formal patch.
>
> Bo Yan has posted something really similar already, however:
>
> https://patchwork.kernel.org/patch/10181101/
>
> so I would prefer to apply a new version of that one with the latest
> comment taken into account:
>
> https://patchwork.kernel.org/patch/10183075/
>
> for the credit to go to the first submitter.
>
Thanks for the information Rafael.
I believe safety check in both cpufreq_suspend() and
cpufreq_resume() would be a good thing to have.
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project