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Message-ID: <4FF29219.10608@linux.vnet.ibm.com>
Date: Tue, 03 Jul 2012 12:02:57 +0530
From: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Linux PM mailing list <linux-pm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
PowerPC email list <linuxppc-dev@...ts.ozlabs.org>
CC: Li Zhong <zhong@...ux.vnet.ibm.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Paul Mackerras <paulus@...ba.org>,
"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: [PATCH v2] cpuidle: (POWER) Replace pseries_notify_cpuidle_add call
with a notifier to fix lockdep problem in start_secondary
cpuidle: (POWER) Replace pseries_notify_cpuidle_add call with a notifier to fix lockdep problem in start_secondary
From: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
Currently the call to pseries_notify_cpuidle_add(), that takes
action on the cpuidle front when a cpu is added/removed
is being made from smp_xics_setup_cpu().
This works fine when the cpus were hot added/removed once the
system is up but causes lockdep issues as
reported https://lkml.org/lkml/2012/5/17/2
during the time of boot.
During boot, on addition of each cpu,
resources were cleared and re-allocated each time, all in critical
section as part of start_secondary() which had interrupts disabled.
To resolve this issue, replacing the pseries_notify_cpuidle_add_cpu() call
with a hotplug notifier. This would prevent cpuidle resources from being
released and allocated each time cpu is onlined during pseries bootup.
Signed-off-by: Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
Reported-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---
This patch has in-corporated review comments
received on the earlier version posted.
v1 -> https://lkml.org/lkml/2012/5/18/174
This applies on 3.5-rc5
---
arch/powerpc/include/asm/processor.h | 2 -
arch/powerpc/platforms/pseries/processor_idle.c | 35 ++++++++++++++++++++---
arch/powerpc/platforms/pseries/smp.c | 1 -
3 files changed, 30 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 413a5ea..53b6dfa 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -389,10 +389,8 @@ extern int powersave_nap; /* set if nap mode can be used in idle loop */
#ifdef CONFIG_PSERIES_IDLE
extern void update_smt_snooze_delay(int snooze);
-extern int pseries_notify_cpuidle_add_cpu(int cpu);
#else
static inline void update_smt_snooze_delay(int snooze) {}
-static inline int pseries_notify_cpuidle_add_cpu(int cpu) { return 0; }
#endif
extern void flush_instruction_cache(void);
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c
index e61483e..da245c0 100644
--- a/arch/powerpc/platforms/pseries/processor_idle.c
+++ b/arch/powerpc/platforms/pseries/processor_idle.c
@@ -186,17 +186,40 @@ static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
.enter = &shared_cede_loop },
};
-int pseries_notify_cpuidle_add_cpu(int cpu)
+static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
+ unsigned long action, void *hcpu)
{
+ int hotcpu = (unsigned long)hcpu;
struct cpuidle_device *dev =
- per_cpu_ptr(pseries_cpuidle_devices, cpu);
+ per_cpu_ptr(pseries_cpuidle_devices, hotcpu);
+
if (dev && cpuidle_get_driver()) {
- cpuidle_disable_device(dev);
- cpuidle_enable_device(dev);
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ cpuidle_pause_and_lock();
+ cpuidle_enable_device(dev);
+ cpuidle_resume_and_unlock();
+ break;
+
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ cpuidle_pause_and_lock();
+ cpuidle_disable_device(dev);
+ cpuidle_resume_and_unlock();
+ break;
+
+ default:
+ return NOTIFY_DONE;
+ }
}
- return 0;
+ return NOTIFY_OK;
}
+static struct notifier_block setup_hotplug_notifier = {
+ .notifier_call = pseries_cpuidle_add_cpu_notifier,
+};
+
/*
* pseries_cpuidle_driver_init()
*/
@@ -321,6 +344,7 @@ static int __init pseries_processor_idle_init(void)
return retval;
}
+ register_cpu_notifier(&setup_hotplug_notifier);
printk(KERN_DEBUG "pseries_idle_driver registered\n");
return 0;
@@ -329,6 +353,7 @@ static int __init pseries_processor_idle_init(void)
static void __exit pseries_processor_idle_exit(void)
{
+ unregister_cpu_notifier(&setup_hotplug_notifier);
pseries_idle_devices_uninit();
cpuidle_unregister_driver(&pseries_idle_driver);
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c
index e16bb8d..71706bc 100644
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -147,7 +147,6 @@ static void __devinit smp_xics_setup_cpu(int cpu)
set_cpu_current_state(cpu, CPU_STATE_ONLINE);
set_default_offline_state(cpu);
#endif
- pseries_notify_cpuidle_add_cpu(cpu);
}
static int __devinit smp_pSeries_kick_cpu(int nr)
--
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