On Wed, 29 Apr 2015, Rafael J. Wysocki wrote: > 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. Incidentally I was debugging this issue as well when I saw this thread. And it turns out that I did report this issue 2 months ago: http://article.gmane.org/gmane.linux.kernel/1892049 What happened? > 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> Tested-by: Nicolas Pitre <nico@xxxxxxxxxx> > --- > > 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(); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
