On Tue, Feb 28, 2012 at 09:57:53PM +0100, Rafael J. Wysocki wrote:
> On Tuesday, February 28, 2012, Paul E. McKenney wrote:
> > On Tue, Feb 28, 2012 at 03:19:43PM +0800, Yong Zhang wrote:
> > > 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@xxxxxxxxxx>
> > >
> > > Got the same warning.
> > > And the patch works on my side.
> > >
> > > Tested-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
> >
> > Thank you, I have added your Tested-by (and Srivatsa's Reviewed-by,
> > for that matter).
> >
> > Any takers for this, or should I just push it up the -tip tree?
>
> I think this patch is for Len, either through ACPI, or through the idle tree.
> Len?
Whichever way it is supposed to go, it reminds me of the need for it every
time I forget to merge it in before testing. ;-)
> Anyway:
>
> Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>
Thank you, applied! The patch appears below with the recent review,
testing, and ack.
Thanx, Paul
------------------------------------------------------------------------
acpi: Fix unprotected smp_processor_id() in acpi_processor_cst_has_changed()
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().
Signed-off-by: Paul E. McKenney <paul.mckenney@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
Tested-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>
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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