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Subject[150/272] intel_idle: open broadcast clock event
2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Shaohua Li <shaohua.li@intel.com>

commit 2a2d31c8dc6f1ebcf5eab1d93a0cb0fb4ed57c7c upstream.

Intel_idle driver uses CLOCK_EVT_NOTIFY_BROADCAST_ENTER
CLOCK_EVT_NOTIFY_BROADCAST_EXIT
for broadcast clock events. The _ENTER/_EXIT doesn't really open broadcast clock
events, please see processor_idle.c for an example. In some situation, this will
cause boot hang, because some CPUs enters idle but local APIC timer stalls.

Reported-and-tested-by: Yan Zheng <zheng.z.yan@intel.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/idle/intel_idle.c | 47 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)

--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -59,6 +59,8 @@
#include <linux/hrtimer.h> /* ktime_get_real() */
#include <trace/events/power.h>
#include <linux/sched.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
#include <asm/mwait.h>

#define INTEL_IDLE_VERSION "0.4"
@@ -73,6 +75,7 @@ static int max_cstate = MWAIT_MAX_NUM_CS

static unsigned int mwait_substates;

+#define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
/* Reliable LAPIC Timer States, bit 1 for C1 etc. */
static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */

@@ -244,6 +247,39 @@ static int intel_idle(struct cpuidle_dev
return usec_delta;
}

+static void __setup_broadcast_timer(void *arg)
+{
+ unsigned long reason = (unsigned long)arg;
+ int cpu = smp_processor_id();
+
+ reason = reason ?
+ CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
+
+ clockevents_notify(reason, &cpu);
+}
+
+static int __cpuinit setup_broadcast_cpuhp_notify(struct notifier_block *n,
+ unsigned long action, void *hcpu)
+{
+ int hotcpu = (unsigned long)hcpu;
+
+ switch (action & 0xf) {
+ case CPU_ONLINE:
+ smp_call_function_single(hotcpu, __setup_broadcast_timer,
+ (void *)true, 1);
+ break;
+ case CPU_DOWN_PREPARE:
+ smp_call_function_single(hotcpu, __setup_broadcast_timer,
+ (void *)false, 1);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata setup_broadcast_notifier = {
+ .notifier_call = setup_broadcast_cpuhp_notify,
+};
+
/*
* intel_idle_probe()
*/
@@ -306,7 +342,11 @@ static int intel_idle_probe(void)
}

if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
- lapic_timer_reliable_states = 0xFFFFFFFF;
+ lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
+ else {
+ smp_call_function(__setup_broadcast_timer, (void *)true, 1);
+ register_cpu_notifier(&setup_broadcast_notifier);
+ }

pr_debug(PREFIX "v" INTEL_IDLE_VERSION
" model 0x%X\n", boot_cpu_data.x86_model);
@@ -429,6 +469,11 @@ static void __exit intel_idle_exit(void)
intel_idle_cpuidle_devices_uninit();
cpuidle_unregister_driver(&intel_idle_driver);

+ if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) {
+ smp_call_function(__setup_broadcast_timer, (void *)false, 1);
+ unregister_cpu_notifier(&setup_broadcast_notifier);
+ }
+
return;
}




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