kthread: add kthread_destroy_worker()

pmladek · torvalds · commit 35033fe9cbbf · 2016-10-11T15:06:33.000-07:00
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/1470754545-17632-7-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Borislav Petkov <bp@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kthread.h b/include/linux/kthread.h
@@ -136,4 +136,6 @@ bool kthread_queue_work(struct kthread_worker *worker,
 void kthread_flush_work(struct kthread_work *work);
 void kthread_flush_worker(struct kthread_worker *worker);
 
+void kthread_destroy_worker(struct kthread_worker *worker);
+
 #endif /* _LINUX_KTHREAD_H */
diff --git 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);
