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SubjectRe: acpi_pad mwait usage
On Tue, Nov 19, 2013 at 10:00:19AM +0100, Peter Zijlstra wrote:
> Hi Len, Rafeal,
>
> I stumbled over acpi_pad (yuck! ;-), but noticed that you don't set the
> task in polling mode while using mwait. This means we'll still happily
> send an IPI to wake you up.
>
> A little something like the below should do; you might even be able to
> remove the smp_mb() but since it is completely undocumented (another
> fail) I couldn't tell if the implied barrier in
> current_set_polling_and_test() suffices to replace it, so I left it.
>
> If it compiles and works; change it to a proper SOB:
>
> Maybe-Signed-off-by: Peter Zijlstra <peterz@infradead.org>

Of course one such driver is insufficient and you lot needed a second;
same issue:

---
drivers/thermal/intel_powerclamp.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/intel_powerclamp.c b/drivers/thermal/intel_powerclamp.c
index 8f181b3f842b..d8111e1ac62e 100644
--- a/drivers/thermal/intel_powerclamp.c
+++ b/drivers/thermal/intel_powerclamp.c
@@ -439,8 +439,11 @@ static int clamp_thread(void *arg)
local_touch_nmi();
stop_critical_timings();
__monitor((void *)&current_thread_info()->flags, 0, 0);
- cpu_relax(); /* allow HT sibling to run */
- __mwait(eax, ecx);
+ if (!current_set_polling_and_test()) {
+ cpu_relax(); /* allow HT sibling to run */
+ __mwait(eax, ecx);
+ __current_clr_polling();
+ }
start_critical_timings();
atomic_inc(&idle_wakeup_counter);
}

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