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SubjectRe: [PATCH] hwmon: (coretemp) Handle frozen hotplug state correctly
On Wed, May 10, 2017 at 04:30:12PM +0200, Thomas Gleixner wrote:
> 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>

Applied, and thanks a lot for fixing the problem!

Guenter

> ---
> 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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