From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Reported-and-tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
Thanks for the testing and ACKs, here it goes again with all tags and
a changelog.
If anything is missing/incorrect, please let me know ASAP as I'm going to
push this to Linus in a couple of days.
---
drivers/cpuidle/cpuidle.c | 16 ++++++++++++++++
kernel/sched/idle.c | 16 ++--------------
2 files changed, 18 insertions(+), 14 deletions(-)
Index: linux-pm/kernel/sched/idle.c
===================================================================
--- linux-pm.orig/kernel/sched/idle.c
+++ linux-pm/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
Index: linux-pm/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/cpuidle.c
+++ linux-pm/drivers/cpuidle/cpuidle.c
@@ -158,9 +158,18 @@ int cpuidle_enter_state(struct cpuidle_d
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_d
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();
--
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