[tip:irq/core] kthread: Add __kthread_should_park()

[tip-bot for Matthias Kaehlcke <tipbot@zytor.com>]

Commit-ID:  0121805d9d2b1fff371e195c28e9b86ae38b5e47
Gitweb:     https://git.kernel.org/tip/0121805d9d2b1fff371e195c28e9b86ae38b5e47
Author:     Matthias Kaehlcke <mka@chromium.org>
AuthorDate: Mon, 28 Jan 2019 15:46:24 -0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sun, 10 Feb 2019 21:51:39 +0100

kthread: Add __kthread_should_park()

kthread_should_park() is used to check if the calling kthread ('current')
should park, but there is no function to check whether an arbitrary kthread
should be parked. The latter is required to plug a CPU hotplug race vs. a
parking ksoftirqd thread.

The new __kthread_should_park() receives a task_struct as parameter to
check if the corresponding kernel thread should be parked.

Call __kthread_should_park() from kthread_should_park() to avoid code
duplication.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Link: https://lkml.kernel.org/r/20190128234625.78241-2-mka@chromium.org

---
 include/linux/kthread.h | 1 +
 kernel/kthread.c        | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index c1961761311d..1577a2d56e9d 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -56,6 +56,7 @@ void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask);
 int kthread_stop(struct task_struct *k);
 bool kthread_should_stop(void);
 bool kthread_should_park(void);
+bool __kthread_should_park(struct task_struct *k);
 bool kthread_freezable_should_stop(bool *was_frozen);
 void *kthread_data(struct task_struct *k);
 void *kthread_probe_data(struct task_struct *k);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 087d18d771b5..65234c89d85b 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -101,6 +101,12 @@ bool kthread_should_stop(void)
 }
 EXPORT_SYMBOL(kthread_should_stop);
 
+bool __kthread_should_park(struct task_struct *k)
+{
+	return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags);
+}
+EXPORT_SYMBOL_GPL(__kthread_should_park);
+
 /**
  * kthread_should_park - should this kthread park now?
  *
@@ -114,7 +120,7 @@ EXPORT_SYMBOL(kthread_should_stop);
  */
 bool kthread_should_park(void)
 {
-	return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags);
+	return __kthread_should_park(current);
 }
 EXPORT_SYMBOL_GPL(kthread_should_park);