Messages in this thread | | | Date | Tue, 28 Feb 2012 11:43:20 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH RFC] acpi: Fix unprotected smp_processor_id() in acpi_processor_cst_has_changed() |
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On 02/24/2012 02:28 AM, Paul E. McKenney wrote:
> The acpi_processor_cst_has_changed() function is invoked from a > CPU_ONLINE or CPU_DEAD function, which might well execute on CPU 0 > even though the CPU being hotplugged is some other CPU. In addition, > acpi_processor_cst_has_changed() invokes smp_processor_id() without > protection, resulting in splats when onlining CPUs. > > This commit therefore changes the smp_processor_id() to pr->id, as is > used elsewhere in the code, for example, in acpi_processor_add(). > > This works for me, but I don't claim to understand ACPI. > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> >
This looks like the right fix to me, observing the disparity between what the comment says (and hence what was intended) vs what the code originally did.
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c > index 0e8e2de..9e57b06 100644 > --- a/drivers/acpi/processor_idle.c > +++ b/drivers/acpi/processor_idle.c > @@ -1159,8 +1159,7 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) > * to make the code that updates C-States be called once. > */ > > - if (smp_processor_id() == 0 && > - cpuidle_get_driver() == &acpi_idle_driver) { > + if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) { > > cpuidle_pause_and_lock(); > /* Protect against cpu-hotplug */ >
Regards, Srivatsa S. Bhat
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