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Merge branches 'timers-urgent-for-linus', 'irq-urgent-for-linus' and 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull {timer,irq,core} fixes from Thomas Gleixner:

 - timer: bug fix for a cpu hotplug race.

 - irq: single bugfix for a wrong return value, which prevents the
   calling function to invoke the software fallback.

 - core: bugfix which plugs two race confitions which can cause hotplug
   per cpu threads to end up on the wrong cpu.

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimer: Don't reinitialize a cpu_base lock on CPU_UP

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip: gic: fix irq_trigger return

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kthread: Prevent unpark race which puts threads on the wrong cpu
This commit is contained in:
Linus Torvalds
2013-04-15 07:03:01 -07:00
parent 41ef2d5678 84cc8fd2fe bad9a43a20 f2530dc71c
commit bb33db7a07
7 changed files with 48 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
kernel/hrtimer.c
View File

@@ -63,6 +63,7 @@
DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
{
.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
.clock_base =
{
{
@@ -1642,8 +1643,6 @@ static void __cpuinit init_hrtimers_cpu(int cpu)
struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
int i;
raw_spin_lock_init(&cpu_base->lock);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
cpu_base->clock_base[i].cpu_base = cpu_base;
timerqueue_init_head(&cpu_base->clock_base[i].active);

52
kernel/kthread.c
View File

@@ -124,12 +124,12 @@ void *kthread_data(struct task_struct *task)
static void __kthread_parkme(struct kthread *self)
{
__set_current_state(TASK_INTERRUPTIBLE);
__set_current_state(TASK_PARKED);
while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) {
if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags))
complete(&self->parked);
schedule();
__set_current_state(TASK_INTERRUPTIBLE);
__set_current_state(TASK_PARKED);
}
clear_bit(KTHREAD_IS_PARKED, &self->flags);
__set_current_state(TASK_RUNNING);
@@ -256,8 +256,13 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
}
EXPORT_SYMBOL(kthread_create_on_node);
static void __kthread_bind(struct task_struct *p, unsigned int cpu)
static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
{
/* Must have done schedule() in kthread() before we set_task_cpu */
if (!wait_task_inactive(p, state)) {
WARN_ON(1);
return;
}
/* It's safe because the task is inactive. */
do_set_cpus_allowed(p, cpumask_of(cpu));
p->flags |= PF_THREAD_BOUND;
@@ -274,12 +279,7 @@ static void __kthread_bind(struct task_struct *p, unsigned int cpu)
*/
void kthread_bind(struct task_struct *p, unsigned int cpu)
{
/* Must have done schedule() in kthread() before we set_task_cpu */
if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
WARN_ON(1);
return;
}
__kthread_bind(p, cpu);
__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(kthread_bind);
@@ -324,6 +324,22 @@ static struct kthread *task_get_live_kthread(struct task_struct *k)
return NULL;
}
static void __kthread_unpark(struct task_struct *k, struct kthread *kthread)
{
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
/*
* We clear the IS_PARKED bit here as we don't wait
* until the task has left the park code. So if we'd
* park before that happens we'd see the IS_PARKED bit
* which might be about to be cleared.
*/
if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
__kthread_bind(k, kthread->cpu, TASK_PARKED);
wake_up_state(k, TASK_PARKED);
}
}
/**
* kthread_unpark - unpark a thread created by kthread_create().
* @k: thread created by kthread_create().
@@ -336,20 +352,8 @@ void kthread_unpark(struct task_struct *k)
{
struct kthread *kthread = task_get_live_kthread(k);
if (kthread) {
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
/*
* We clear the IS_PARKED bit here as we don't wait
* until the task has left the park code. So if we'd
* park before that happens we'd see the IS_PARKED bit
* which might be about to be cleared.
*/
if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
__kthread_bind(k, kthread->cpu);
wake_up_process(k);
}
}
if (kthread)
__kthread_unpark(k, kthread);
put_task_struct(k);
}
@@ -407,7 +411,7 @@ int kthread_stop(struct task_struct *k)
trace_sched_kthread_stop(k);
if (kthread) {
set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
__kthread_unpark(k, kthread);
wake_up_process(k);
wait_for_completion(&kthread->exited);
}

14
kernel/smpboot.c
View File

@@ -185,8 +185,18 @@ __smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
}
get_task_struct(tsk);
*per_cpu_ptr(ht->store, cpu) = tsk;
if (ht->create)
ht->create(cpu);
if (ht->create) {
/*
* Make sure that the task has actually scheduled out
* into park position, before calling the create
* callback. At least the migration thread callback
* requires that the task is off the runqueue.
*/
if (!wait_task_inactive(tsk, TASK_PARKED))
WARN_ON(1);
else
ht->create(cpu);
}
return 0;
}