linux-kernel - [PATCH v10 06/11] kthread: Add kthread_destroy

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Date:	Tue,  9 Aug 2016 16:55:40 +0200
From:	Petr Mladek <pmladek@...e.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Josh Triplett <josh@...htriplett.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jiri Kosina <jkosina@...e.cz>, Borislav Petkov <bp@...e.de>,
	Michal Hocko <mhocko@...e.cz>, linux-mm@...ck.org,
	Vlastimil Babka <vbabka@...e.cz>, linux-api@...r.kernel.org,
	linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: [PATCH v10 06/11] 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.

Signed-off-by: Petr Mladek <pmladek@...e.com>
---
 include/linux/kthread.h |  2 ++
 kernel/kthread.c        | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index daeb2befbabf..afc8939da861 100644
--- 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
index d9ba5e229cd3..3dc7f26d84d7 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -819,3 +819,26 @@ 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);
-- 
1.8.5.6