kthread: add kthread_destroy_worker()

The current kthread worker users call flush() and stop() explicitly.
This function does the same plus it frees the kthread_worker struct
in one call.

It is supposed to be used together with kthread_create_worker*() that
allocates struct kthread_worker.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Petr Mladek <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Josh Triplett <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 23 insertions, 0 deletions

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 12695e68ed00..f874300dfce5 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -823,3 +823,26 @@ void kthread_flush_worker(struct kthread_worker *worker)
 	wait_for_completion(&fwork.done);
 }
 EXPORT_SYMBOL_GPL(kthread_flush_worker);
+
+/**
+ * kthread_destroy_worker - destroy a kthread worker
+ * @worker: worker to be destroyed
+ *
+ * Flush and destroy @worker.  The simple flush is enough because the kthread
+ * worker API is used only in trivial scenarios.  There are no multi-step state
+ * machines needed.
+ */
+void kthread_destroy_worker(struct kthread_worker *worker)
+{
+	struct task_struct *task;
+
+	task = worker->task;
+	if (WARN_ON(!task))
+		return;
+
+	kthread_flush_worker(worker);
+	kthread_stop(task);
+	WARN_ON(!list_empty(&worker->work_list));
+	kfree(worker);
+}
+EXPORT_SYMBOL(kthread_destroy_worker);