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authorPeter Zijlstra <peterz@infradead.org>2018-06-07 10:55:56 +0200
committerIngo Molnar <mingo@kernel.org>2018-07-03 09:20:44 +0200
commitf83ee19be4272564ad592ef90145db7295229490 (patch)
tree181bd1628e2b233cd9e3b44ac6e608c24b7f34b4 /kernel/kthread.c
parent167a88677b05d6a810f23b871cfb2b5db1808e60 (diff)
kthread: Simplify kthread_park() completion
Oleg explains the reason we could hit park+park is that smpboot_update_cpumask_percpu_thread()'s for_each_cpu_and(cpu, &tmp, cpu_online_mask) smpboot_park_kthread(); turns into: for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)and) smpboot_park_kthread(); on UP, ignoring the mask. But since we just completely removed that function, this is no longer relevant. So revert commit: b1f5b378e126 ("kthread: Allow kthread_park() on a parked kthread") Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/kthread.c')
-rw-r--r--kernel/kthread.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 750cb8082694..11b591ee51ab 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -190,7 +190,7 @@ static void __kthread_parkme(struct kthread *self)
if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags))
break;
- complete_all(&self->parked);
+ complete(&self->parked);
schedule();
}
__set_current_state(TASK_RUNNING);
@@ -465,7 +465,6 @@ void kthread_unpark(struct task_struct *k)
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
__kthread_bind(k, kthread->cpu, TASK_PARKED);
- reinit_completion(&kthread->parked);
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
/*
* __kthread_parkme() will either see !SHOULD_PARK or get the wakeup.
@@ -493,6 +492,9 @@ int kthread_park(struct task_struct *k)
if (WARN_ON(k->flags & PF_EXITING))
return -ENOSYS;
+ if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags)))
+ return -EBUSY;
+
set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
if (k != current) {
wake_up_process(k);