Commit 89878baa73f0f1c679355006bd8632e5d78f96c2 introduced the flag CPUIDLE_FLAG_TIMER_STOP where we specify a specific idle state stops the local timer.
Commit a06df062a189a8d5588babb8bf0bb78672497798 introduced the initialization of the timer broadcast framework depending of the flag presence.
If a system is booted with some cpus offline, by setting for example, maxcpus=1 in the kernel command line, and then they are set online, the timer broadcast won't be setup automatically.
Fix this by adding the cpu hotplug notifier and enable/disable the timer broadcast automatically. So no need to handle that at the arch specific driver level like eg. intel_idle does.
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org --- drivers/cpuidle/driver.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+)
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index 3ac499d..e976994 100644 --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -10,6 +10,7 @@
#include <linux/mutex.h> #include <linux/module.h> +#include <linux/cpu.h> #include <linux/cpuidle.h> #include <linux/cpumask.h> #include <linux/clockchips.h> @@ -147,6 +148,48 @@ static void cpuidle_setup_broadcast_timer(void *arg) }
/** + * cpuidle_hotplug_notify: notifier callback when a cpu is onlined/offlined + * @n: the notifier block + * @action: an unsigned long giving the event related to the notification + * @hcpu: a void pointer but used as the cpu number which the event is related + * + * The kernel can boot with some cpus offline, we have to init the timer + * broadcast for these cpus when they are onlined. Also we have to disable + * the timer broadcast when the cpu is down. + * + * Returns NOTIFY_OK + */ +static int cpuidle_hotplug_notify(struct notifier_block *n, + unsigned long action, void *hcpu) +{ + int cpu = (unsigned long)hcpu; + struct cpuidle_driver *drv; + + drv = __cpuidle_get_cpu_driver(cpu); + if (!drv || !drv->bctimer) + goto out; + + switch (action & 0xf) { + case CPU_ONLINE: + smp_call_function_single(cpu, cpuidle_setup_broadcast_timer, + (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, + 1); + break; + case CPU_DEAD: + smp_call_function_single(cpu, cpuidle_setup_broadcast_timer, + (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, + 1); + break; + } +out: + return NOTIFY_OK; +} + +static struct notifier_block cpuidle_hotplug_notifier = { + .notifier_call = cpuidle_hotplug_notify, +}; + +/** * __cpuidle_driver_init - initialize the driver's internal data * @drv: a valid pointer to a struct cpuidle_driver * @@ -262,6 +305,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv) ret = __cpuidle_register_driver(drv); spin_unlock(&cpuidle_driver_lock);
+ if (!ret) + ret = register_cpu_notifier(&cpuidle_hotplug_notifier); + return ret; } EXPORT_SYMBOL_GPL(cpuidle_register_driver); @@ -276,6 +322,8 @@ EXPORT_SYMBOL_GPL(cpuidle_register_driver); */ void cpuidle_unregister_driver(struct cpuidle_driver *drv) { + unregister_cpu_notifier(&cpuidle_hotplug_notifier); + spin_lock(&cpuidle_driver_lock); __cpuidle_unregister_driver(drv); spin_unlock(&cpuidle_driver_lock);