From: Preeti U Murthy Date: Fri, 7 Feb 2014 08:06:52 +0000 (+0530) Subject: cpuidle: Handle clockevents_notify(BROADCAST_ENTER) failure X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ba8f20c2eb4158a443e9d6a909aee5010efa0c69;p=linux-beck.git cpuidle: Handle clockevents_notify(BROADCAST_ENTER) failure Some archs set the CPUIDLE_FLAG_TIMER_STOP flag for idle states in which the local timers stop. The cpuidle_idle_call() currently handles such idle states by calling into the broadcast framework so as to wakeup CPUs at their next wakeup event. With the hrtimer mode of broadcast, the BROADCAST_ENTER call into the broadcast frameowork can fail for archs that do not have an external clock device to handle wakeups and the CPU in question has thus to be made the stand by CPU. This patch handles such cases by failing the call into cpuidle so that the arch can take some default action. The arch will certainly not enter a similar idle state because a failed cpuidle call will also implicitly indicate that the broadcast framework has not registered this CPU to be woken up. Hence we are safe if we fail the cpuidle call. In the process move the functions that trace idle statistics just before and after the entry and exit into idle states respectively. In other scenarios where the call to cpuidle fails, we end up not tracing idle entry and exit since a decision on an idle state could not be taken. Similarly when the call to broadcast framework fails, we skip tracing idle statistics because we are in no further position to take a decision on an alternative idle state to enter into. Signed-off-by: Preeti U Murthy Cc: deepthi@linux.vnet.ibm.com Cc: paulmck@linux.vnet.ibm.com Cc: fweisbec@gmail.com Cc: paulus@samba.org Cc: srivatsa.bhat@linux.vnet.ibm.com Cc: svaidy@linux.vnet.ibm.com Cc: peterz@infradead.org Cc: benh@kernel.crashing.org Acked-by: Rafael J. Wysocki Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20140207080652.17187.66344.stgit@preeti.in.ibm.com Signed-off-by: Thomas Gleixner --- diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index a55e68f2cfc8..09d05ab262be 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -140,12 +140,14 @@ int cpuidle_idle_call(void) return 0; } - trace_cpu_idle_rcuidle(next_state, dev->cpu); - broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP); - if (broadcast) - clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); + if (broadcast && + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu)) + return -EBUSY; + + + trace_cpu_idle_rcuidle(next_state, dev->cpu); if (cpuidle_state_is_coupled(dev, drv, next_state)) entered_state = cpuidle_enter_state_coupled(dev, drv, @@ -153,11 +155,11 @@ int cpuidle_idle_call(void) else entered_state = cpuidle_enter_state(dev, drv, next_state); + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); + if (broadcast) clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu); - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); - /* give the governor an opportunity to reflect on the outcome */ if (cpuidle_curr_governor->reflect) cpuidle_curr_governor->reflect(dev, entered_state);