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Date: Thu, 14 Feb 2013 09:47:59 -0800
From: tip-bot for Thomas Gleixner <tglx@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
rusty@...tcorp.com.au, pjt@...gle.com, peterz@...radead.org,
srivatsa.bhat@...ux.vnet.ibm.com, rw@...utronix.de,
paulmck@...ux.vnet.ibm.com, arjan@...radead.org,
tglx@...utronix.de, magnus.damm@...il.com
Subject: [tip:smp/hotplug] stop_machine:
Store task reference in a separate per cpu variable
Commit-ID: 860a0ffaa3e1a9cf0ebb5f43d6a2a2ce67463e93
Gitweb: http://git.kernel.org/tip/860a0ffaa3e1a9cf0ebb5f43d6a2a2ce67463e93
Author: Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Thu, 31 Jan 2013 12:11:13 +0000
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 14 Feb 2013 15:29:37 +0100
stop_machine: Store task reference in a separate per cpu variable
To allow the stopper thread being managed by the smpboot thread
infrastructure separate out the task storage from the stopper data
structure.
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Cc: Arjan van de Veen <arjan@...radead.org>
Cc: Paul Turner <pjt@...gle.com>
Cc: Richard Weinberger <rw@...utronix.de>
Cc: Magnus Damm <magnus.damm@...il.com>
Link: http://lkml.kernel.org/r/20130131120741.626690384@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
kernel/stop_machine.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 2f194e9..aaac68c 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -37,10 +37,10 @@ struct cpu_stopper {
spinlock_t lock;
bool enabled; /* is this stopper enabled? */
struct list_head works; /* list of pending works */
- struct task_struct *thread; /* stopper thread */
};
static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
+static DEFINE_PER_CPU(struct task_struct *, cpu_stopper_task);
static bool stop_machine_initialized = false;
static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
@@ -62,16 +62,18 @@ static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed)
}
/* queue @work to @stopper. if offline, @work is completed immediately */
-static void cpu_stop_queue_work(struct cpu_stopper *stopper,
- struct cpu_stop_work *work)
+static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
{
+ struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+ struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
+
unsigned long flags;
spin_lock_irqsave(&stopper->lock, flags);
if (stopper->enabled) {
list_add_tail(&work->list, &stopper->works);
- wake_up_process(stopper->thread);
+ wake_up_process(p);
} else
cpu_stop_signal_done(work->done, false);
@@ -108,7 +110,7 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };
cpu_stop_init_done(&done, 1);
- cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), &work);
+ cpu_stop_queue_work(cpu, &work);
wait_for_completion(&done.completion);
return done.executed ? done.ret : -ENOENT;
}
@@ -130,7 +132,7 @@ void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
struct cpu_stop_work *work_buf)
{
*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, };
- cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), work_buf);
+ cpu_stop_queue_work(cpu, work_buf);
}
/* static data for stop_cpus */
@@ -159,8 +161,7 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask,
*/
preempt_disable();
for_each_cpu(cpu, cpumask)
- cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu),
- &per_cpu(stop_cpus_work, cpu));
+ cpu_stop_queue_work(cpu, &per_cpu(stop_cpus_work, cpu));
preempt_enable();
}
@@ -304,12 +305,11 @@ static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
{
unsigned int cpu = (unsigned long)hcpu;
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
- struct task_struct *p;
+ struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
- BUG_ON(stopper->thread || stopper->enabled ||
- !list_empty(&stopper->works));
+ BUG_ON(p || stopper->enabled || !list_empty(&stopper->works));
p = kthread_create_on_node(cpu_stopper_thread,
stopper,
cpu_to_node(cpu),
@@ -319,12 +319,12 @@ static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
get_task_struct(p);
kthread_bind(p, cpu);
sched_set_stop_task(cpu, p);
- stopper->thread = p;
+ per_cpu(cpu_stopper_task, cpu) = p;
break;
case CPU_ONLINE:
/* strictly unnecessary, as first user will wake it */
- wake_up_process(stopper->thread);
+ wake_up_process(p);
/* mark enabled */
spin_lock_irq(&stopper->lock);
stopper->enabled = true;
@@ -339,7 +339,7 @@ static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
sched_set_stop_task(cpu, NULL);
/* kill the stopper */
- kthread_stop(stopper->thread);
+ kthread_stop(p);
/* drain remaining works */
spin_lock_irq(&stopper->lock);
list_for_each_entry(work, &stopper->works, list)
@@ -347,8 +347,8 @@ static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
stopper->enabled = false;
spin_unlock_irq(&stopper->lock);
/* release the stopper */
- put_task_struct(stopper->thread);
- stopper->thread = NULL;
+ put_task_struct(p);
+ per_cpu(cpu_stopper_task, cpu) = NULL;
break;
}
#endif
--
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