On Mon, Jul 30, 2012 at 10:08:47AM -0700, Paul E. McKenney wrote:
> On Mon, Jul 30, 2012 at 11:07:47PM +0800, Feng Tang wrote:
> > Hi Paul,
> >
> > On Mon, 30 Jul 2012 06:39:13 -0700
> > "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
> >
> > > On Mon, Jul 30, 2012 at 03:15:59PM +0800, Feng Tang wrote:
> > > > Hi All,
> > > >
> > > > When I debugged a suspend/resume bug, I found that tick_broadcast_mask
> > > > is
> > > > not restored for a CPU after it is offline/onlined since kernel 3.4,
> > > > while
> > > > it's fine for 3.3.
> > >
> > > Could you please try 3.5?
> >
> > Yes, it's the same for 3.5
>
> Thank you for checking, Feng.
>
> Len, the comment above the change says:
>
> /*
> * FIXME: Design the ACPI notification to make it once per
> * system instead of once per-cpu. This condition is a hack
> * to make the code that updates C-States be called once.
> */
>
> Is it time for this design-level change? Or is there something obvious
> that I missed when fixing the smp_processor_id() splat?
>
> I could revert back, but use raw_smp_processor_id() rather than
> smp_processor_id(), but that feels like papering over a problem rather
> than fixing it.
But should papering be appropriate, here is the patch.
Thanx, Paul
------------------------------------------------------------------------
ACPI: Repair fix to unprotected smp_processor_id()
Commit 9505626d (ACPI: Fix unprotected smp_processor_id() in
acpi_processor_cst_has_changed()) introduced a suspend/resume bug.
This commit therefore introduces a bug-for-bug compatible fix for the
original problem.
Reported-by: Feng Tang <feng.t...@intel.com>
Signed-off-by: Paul E. McKenney <paul.mcken...@linaro.org>
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 47a8caa..19c151a 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1218,7 +1218,8 @@ int acpi_processor_cst_has_changed(struct acpi_processor
*pr)
* to make the code that updates C-States be called once.
*/
- if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) {
+ if (raw_smp_processor_id() == 0 &&
+ cpuidle_get_driver() == &acpi_idle_driver) {
cpuidle_pause_and_lock();
/* Protect against cpu-hotplug */
--
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