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SubjectRe: [PATCH] hwmon: (coretemp) Handle frozen hotplug state correctly
2017-05-10 23:09 GMT+03:00 Guenter Roeck <linux@roeck-us.net>:
> On Wed, May 10, 2017 at 10:16:33PM +0300, Tommi Rantala wrote:
>> 2017-05-10 17:30 GMT+03:00 Thomas Gleixner <tglx@linutronix.de>:
>> > The recent conversion to the hotplug state machine missed that the original
>> > hotplug notifiers did not execute in the frozen state, which is used on
>> > suspend on resume.
>> >
>> > This does not matter on single socket machines, but on multi socket systems
>> > this breaks when the device for a non-boot socket is removed when the last
>> > CPU of that socket is brought offline. The device removal locks up the
>> > machine hard w/o any debug output.
>> >
>> > Prevent executing the hotplug callbacks when cpuhp_tasks_frozen is true.
>> >
>> > Thanks to Tommi for providing debug information patiently while I failed to
>> > spot the obvious.
>> >
>> > Fixes: e00ca5df37ad ("hwmon: (coretemp) Convert to hotplug state machine")
>> > Reported-by: Tommi Rantala <tt.rantala@gmail.com>
>> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>>
>> Many thanks, I can confirm that it works well!
>>
> Ok if I add your Tested-by: ?

Sure!

Tested-by: Tommi Rantala <tt.rantala@gmail.com>

> Thanks,
> Guenter
>
>> -Tommi
>>
>> > ---
>> > drivers/hwmon/coretemp.c | 14 ++++++++++++++
>> > 1 file changed, 14 insertions(+)
>> >
>> > --- a/drivers/hwmon/coretemp.c
>> > +++ b/drivers/hwmon/coretemp.c
>> > @@ -605,6 +605,13 @@ static int coretemp_cpu_online(unsigned
>> > struct platform_data *pdata;
>> >
>> > /*
>> > + * Don't execute this on resume as the offline callback did
>> > + * not get executed on suspend.
>> > + */
>> > + if (cpuhp_tasks_frozen)
>> > + return 0;
>> > +
>> > + /*
>> > * CPUID.06H.EAX[0] indicates whether the CPU has thermal
>> > * sensors. We check this bit only, all the early CPUs
>> > * without thermal sensors will be filtered out.
>> > @@ -654,6 +661,13 @@ static int coretemp_cpu_offline(unsigned
>> > struct temp_data *tdata;
>> > int indx, target;
>> >
>> > + /*
>> > + * Don't execute this on suspend as the device remove locks
>> > + * up the machine.
>> > + */
>> > + if (cpuhp_tasks_frozen)
>> > + return 0;
>> > +
>> > /* If the physical CPU device does not exist, just return */
>> > if (!pdev)
>> > return 0;

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