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Message-ID: <tip-c00166d87e730088d919814020e96ffed129d0d1@git.kernel.org>
Date: Tue, 20 Oct 2015 02:33:40 -0700
From: tip-bot for Oleg Nesterov <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: tj@...nel.org, tglx@...utronix.de, mingo@...nel.org,
riel@...hat.com, paulmck@...ux.vnet.ibm.com,
akpm@...ux-foundation.org, oleg@...hat.com, efault@....de,
linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
peterz@...radead.org, hpa@...or.com
Subject: [tip:sched/core] stop_machine: Kill smp_hotplug_thread->
pre_unpark, introduce stop_machine_unpark()
Commit-ID: c00166d87e730088d919814020e96ffed129d0d1
Gitweb: http://git.kernel.org/tip/c00166d87e730088d919814020e96ffed129d0d1
Author: Oleg Nesterov <oleg@...hat.com>
AuthorDate: Fri, 9 Oct 2015 18:00:49 +0200
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 20 Oct 2015 10:23:55 +0200
stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
1. Change smpboot_unpark_thread() to check ->selfparking, just
like smpboot_park_thread() does.
2. Introduce stop_machine_unpark() which sets ->enabled and calls
kthread_unpark().
3. Change smpboot_thread_call() and cpu_stop_init() to call
stop_machine_unpark() by hand.
This way:
- IMO the ->selfparking logic becomes more consistent.
- We can kill the smp_hotplug_thread->pre_unpark() method.
- We can easily unpark the stopper thread earlier. Say, we
can move stop_machine_unpark() from smpboot_thread_call()
to sched_cpu_active() as Peter suggests.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: heiko.carstens@...ibm.com
Link: http://lkml.kernel.org/r/20151009160049.GA10166@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
include/linux/smpboot.h | 4 ----
include/linux/stop_machine.h | 1 +
kernel/cpu.c | 1 +
kernel/smpboot.c | 5 ++---
kernel/stop_machine.c | 10 +++++++++-
5 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h
index e6109a6..12910cf 100644
--- a/include/linux/smpboot.h
+++ b/include/linux/smpboot.h
@@ -24,9 +24,6 @@ struct smpboot_thread_data;
* parked (cpu offline)
* @unpark: Optional unpark function, called when the thread is
* unparked (cpu online)
- * @pre_unpark: Optional unpark function, called before the thread is
- * unparked (cpu online). This is not guaranteed to be
- * called on the target cpu of the thread. Careful!
* @cpumask: Internal state. To update which threads are unparked,
* call smpboot_update_cpumask_percpu_thread().
* @selfparking: Thread is not parked by the park function.
@@ -42,7 +39,6 @@ struct smp_hotplug_thread {
void (*cleanup)(unsigned int cpu, bool online);
void (*park)(unsigned int cpu);
void (*unpark)(unsigned int cpu);
- void (*pre_unpark)(unsigned int cpu);
cpumask_var_t cpumask;
bool selfparking;
const char *thread_comm;
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 7b76362..0adedca 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -34,6 +34,7 @@ void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
void stop_machine_park(int cpu);
+void stop_machine_unpark(int cpu);
#else /* CONFIG_SMP */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index c85df27..6467521 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -475,6 +475,7 @@ static int smpboot_thread_call(struct notifier_block *nfb,
case CPU_DOWN_FAILED:
case CPU_ONLINE:
+ stop_machine_unpark(cpu);
smpboot_unpark_threads(cpu);
break;
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index a818cbc..d264f59 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -222,9 +222,8 @@ static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cp
{
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
- if (ht->pre_unpark)
- ht->pre_unpark(cpu);
- kthread_unpark(tsk);
+ if (!ht->selfparking)
+ kthread_unpark(tsk);
}
void smpboot_unpark_threads(unsigned int cpu)
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 91fbb10..59096a5 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -513,6 +513,14 @@ static void cpu_stop_unpark(unsigned int cpu)
spin_unlock_irq(&stopper->lock);
}
+void stop_machine_unpark(int cpu)
+{
+ struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+
+ cpu_stop_unpark(cpu);
+ kthread_unpark(stopper->thread);
+}
+
static struct smp_hotplug_thread cpu_stop_threads = {
.store = &cpu_stopper.thread,
.thread_should_run = cpu_stop_should_run,
@@ -521,7 +529,6 @@ static struct smp_hotplug_thread cpu_stop_threads = {
.create = cpu_stop_create,
.setup = cpu_stop_unpark,
.park = cpu_stop_park,
- .pre_unpark = cpu_stop_unpark,
.selfparking = true,
};
@@ -537,6 +544,7 @@ static int __init cpu_stop_init(void)
}
BUG_ON(smpboot_register_percpu_thread(&cpu_stop_threads));
+ stop_machine_unpark(raw_smp_processor_id());
stop_machine_initialized = true;
return 0;
}
--
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