[PATCH] x86/cpuidle: restrict scope of mwait_ptr in acpi_dead_idle()

[PATCH] x86/cpuidle: restrict scope of mwait_ptr in acpi_dead_idle()

[Jan Beulich]

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... just to make sure it doesn't get used improperly (resulting from
the discussion around what became c/s 24968:8964c223836c).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -565,7 +565,6 @@ static void acpi_dead_idle(void)
 {
     struct acpi_processor_power *power;
     struct acpi_processor_cx *cx;
-    void *mwait_ptr;
 
     if ( (power = processor_powers[smp_processor_id()]) == NULL )
         goto default_halt;
@@ -573,10 +572,10 @@ static void acpi_dead_idle(void)
     if ( (cx = &power->states[power->count-1]) == NULL )
         goto default_halt;
 
-    mwait_ptr = (void *)&mwait_wakeup(smp_processor_id());
-
     if ( cx->entry_method == ACPI_CSTATE_EM_FFH )
     {
+        void *mwait_ptr = &mwait_wakeup(smp_processor_id());
+
         /*
          * Cache must be flushed as the last operation before sleeping.
          * Otherwise, CPU may still hold dirty data, breaking cache coherency,




[-- Attachment #2: x86-cpuidle-scope.patch --]
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x86/cpuidle: restrict scope of mwait_ptr in acpi_dead_idle()

... just to make sure it doesn't get used improperly (resulting from
the discussion around what became c/s 24968:8964c223836c).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -565,7 +565,6 @@ static void acpi_dead_idle(void)
 {
     struct acpi_processor_power *power;
     struct acpi_processor_cx *cx;
-    void *mwait_ptr;
 
     if ( (power = processor_powers[smp_processor_id()]) == NULL )
         goto default_halt;
@@ -573,10 +572,10 @@ static void acpi_dead_idle(void)
     if ( (cx = &power->states[power->count-1]) == NULL )
         goto default_halt;
 
-    mwait_ptr = (void *)&mwait_wakeup(smp_processor_id());
-
     if ( cx->entry_method == ACPI_CSTATE_EM_FFH )
     {
+        void *mwait_ptr = &mwait_wakeup(smp_processor_id());
+
         /*
          * Cache must be flushed as the last operation before sleeping.
          * Otherwise, CPU may still hold dirty data, breaking cache coherency,

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Re: [PATCH] x86/cpuidle: restrict scope of mwait_ptr in acpi_dead_idle()

[Keir Fraser]

On 06/03/2012 14:58, "Jan Beulich" <JBeulich@suse.com> wrote:

> ... just to make sure it doesn't get used improperly (resulting from
> the discussion around what became c/s 24968:8964c223836c).
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Keir Fraser <keir@xen.org>

> --- a/xen/arch/x86/acpi/cpu_idle.c
> +++ b/xen/arch/x86/acpi/cpu_idle.c
> @@ -565,7 +565,6 @@ static void acpi_dead_idle(void)
>  {
>      struct acpi_processor_power *power;
>      struct acpi_processor_cx *cx;
> -    void *mwait_ptr;
>  
>      if ( (power = processor_powers[smp_processor_id()]) == NULL )
>          goto default_halt;
> @@ -573,10 +572,10 @@ static void acpi_dead_idle(void)
>      if ( (cx = &power->states[power->count-1]) == NULL )
>          goto default_halt;
>  
> -    mwait_ptr = (void *)&mwait_wakeup(smp_processor_id());
> -
>      if ( cx->entry_method == ACPI_CSTATE_EM_FFH )
>      {
> +        void *mwait_ptr = &mwait_wakeup(smp_processor_id());
> +
>          /*
>           * Cache must be flushed as the last operation before sleeping.
>           * Otherwise, CPU may still hold dirty data, breaking cache
> coherency,
> 
> 
> 
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