cpuidle: Run tick_broadcast_exit() with disabled interrupts

Commit 335f49196fd6 (sched/idle: Use explicit broadcast oneshot
control function) replaced clockevents_notify() invocations in
cpuidle_idle_call() with direct calls to tick_broadcast_enter()
and tick_broadcast_exit(), but it overlooked the fact that
interrupts were already enabled before calling the latter which
led to functional breakage on systems using idle states with the
CPUIDLE_FLAG_TIMER_STOP flag set.

Fix that by moving the invocations of tick_broadcast_enter()
and tick_broadcast_exit() down into cpuidle_enter_state() where
interrupts are still disabled when tick_broadcast_exit() is
called.  Also ensure that interrupts will be disabled before
running tick_broadcast_exit() even if they have been enabled by
the idle state's ->enter callback.  Trigger a WARN_ON_ONCE() in
that case, as we generally don't want that to happen for states
with CPUIDLE_FLAG_TIMER_STOP set.

Fixes: 335f49196fd6 (sched/idle: Use explicit broadcast oneshot control function)
Reported-and-tested-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 18 insertions, 14 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 7a73a279e179..61c417b9e53f 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -158,9 +158,18 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
         int entered_state;
 
         struct cpuidle_state *target_state = &drv->states[index];
+        bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
         ktime_t time_start, time_end;
         s64 diff;
 
+        /*
+         * Tell the time framework to switch to a broadcast timer because our
+         * local timer will be shut down.  If a local timer is used from another
+         * CPU as a broadcast timer, this call may fail if it is not available.
+         */
+        if (broadcast && tick_broadcast_enter())
+                return -EBUSY;
+
         trace_cpu_idle_rcuidle(index, dev->cpu);
         time_start = ktime_get();
 
@@ -169,6 +178,13 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
         time_end = ktime_get();
         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 
+        if (broadcast) {
+                if (WARN_ON_ONCE(!irqs_disabled()))
+                        local_irq_disable();
+
+                tick_broadcast_exit();
+        }
+
         if (!cpuidle_state_is_coupled(dev, drv, entered_state))
                 local_irq_enable();
 
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index deef1caa94c6..fefcb1fa5160 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -81,7 +81,6 @@ static void cpuidle_idle_call(void)
         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
         int next_state, entered_state;
-        unsigned int broadcast;
         bool reflect;
 
         /*
@@ -150,17 +149,6 @@ static void cpuidle_idle_call(void)
                 goto exit_idle;
         }
 
-        broadcast = drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP;
-
-        /*
-         * Tell the time framework to switch to a broadcast timer
-         * because our local timer will be shutdown. If a local timer
-         * is used from another cpu as a broadcast timer, this call may
-         * fail if it is not available
-         */
-        if (broadcast && tick_broadcast_enter())
-                goto use_default;
-
         /* Take note of the planned idle state. */
         idle_set_state(this_rq(), &drv->states[next_state]);
 
@@ -174,8 +162,8 @@ static void cpuidle_idle_call(void)
         /* The cpu is no longer idle or about to enter idle. */
         idle_set_state(this_rq(), NULL);
 
-        if (broadcast)
-                tick_broadcast_exit();
+        if (entered_state == -EBUSY)
+                goto use_default;
 
         /*
          * Give the governor an opportunity to reflect on the outcome