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    SubjectRe: [PATCH RFC] acpi: Fix unprotected smp_processor_id() in acpi_processor_cst_has_changed()
    On Thu, Feb 23, 2012 at 12:58:05PM -0800, 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>

    Got the same warning.
    And the patch works on my side.

    Tested-by: Yong Zhang <yong.zhang0@gmail.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 */
    >
    > --
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    --
    Only stand for myself


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