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stop_machine: Store task reference in a separate per cpu variable

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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@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Weinberger <rw@linutronix.de>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130131120741.626690384@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2013-01-31 12:11:13 +00:00
parent 7d7e499f73
commit 860a0ffaa3
1 changed files with 16 additions and 16 deletions
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32
kernel/stop_machine.c
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@ -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