cpuidle: Set polling in poll_idle

poll_idle is the archetypal polling idle loop; tell the core idle
code about it.

This avoids pointless IPIs when all of the other cpuidle states are
disabled.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: nicolas.pitre@linaro.org
Cc: umgwanakikbuti@gmail.com
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Link: http://lkml.kernel.org/r/c65ce49615d338bae8fb79df5daffab19353c900.1401902905.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 136d6a283e0a..9634f20e3926 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -187,8 +187,11 @@ static int poll_idle(struct cpuidle_device *dev,
 
         t1 = ktime_get();
         local_irq_enable();
-        while (!need_resched())
-                cpu_relax();
+        if (!current_set_polling_and_test()) {
+                while (!need_resched())
+                        cpu_relax();
+        }
+        current_clr_polling();
 
         t2 = ktime_get();
         diff = ktime_to_us(ktime_sub(t2, t1));