qcacmn: Add qdf_thread_run and qdf_thread_join APIs

For cases where you want to create and immediately start a thread, the
Linux kernel has the kthread_run() API. Create a QDF wrapper for
kthread_run() as well as companion APIs for waiting for a thread to exit
and one to check if the current thread should exit.

Change-Id: Ia4e107010fc400f764661a9b36aceea970841ade
CRs-Fixed: 2270827

qdf/inc/qdf_threads.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2017 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2014-2018 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -28,6 +28,7 @@
 #include "i_qdf_threads.h"
 
 typedef __qdf_thread_t qdf_thread_t;
+typedef QDF_STATUS (*qdf_thread_func)(void *context);
 
 /* Function declarations and documenation */
 
@@ -56,6 +57,38 @@ void qdf_set_user_nice(qdf_thread_t *thread, long nice);
 qdf_thread_t *qdf_create_thread(int (*thread_handler)(void *data), void *data,
 				const char thread_name[]);
 
+/**
+ * qdf_thread_run() - run the given function in a new thread
+ *
+ * You must call qdf_thread_join() to avoid a reasource leak!
+ *
+ * For more flexibility, use qdf_create_thread() instead.
+ *
+ * Return: a new qdf_thread pointer
+ */
+qdf_thread_t *qdf_thread_run(qdf_thread_func callback, void *context);
+
+/**
+ * qdf_thread_join() - signal and wait for a thread to stop
+ *
+ * This sets a flag that the given thread can check to see if it should exit.
+ * The thread can check to see if this flag has been set by calling
+ * qdf_thread_should_stop().
+ *
+ * Return: QDF_STATUS - the return value from the thread function
+ */
+QDF_STATUS qdf_thread_join(qdf_thread_t *thread);
+
+/**
+ * qdf_thread_should_stop() - true if the current thread was signalled to stop
+ *
+ * If qdf_thread_join() has been called on the current thread, this API returns
+ * true. Otherwise, this returns false.
+ *
+ * Return: true if the current thread should stop
+ */
+bool qdf_thread_should_stop(void);
+
 /**
  * qdf_wake_up_process() - wake up given thread
  * @thread: pointer to thread which needs to be woken up

qdf/linux/src/qdf_threads.c

@@ -40,6 +40,8 @@
 
 /* Function declarations and documenation */
 
+typedef int (*qdf_thread_os_func)(void *data);
+
 /**
  *  qdf_sleep() - sleep
  *  @ms_interval : Number of milliseconds to suspend the current thread.
@@ -117,6 +119,43 @@ qdf_thread_t *qdf_create_thread(int (*thread_handler)(void *data), void *data,
 }
 qdf_export_symbol(qdf_create_thread);
 
+static uint16_t qdf_thread_id;
+
+qdf_thread_t *qdf_thread_run(qdf_thread_func callback, void *context)
+{
+	struct task_struct *thread;
+
+	thread = kthread_create((qdf_thread_os_func)callback, context,
+				"qdf %u", qdf_thread_id++);
+	if (IS_ERR(thread))
+		return NULL;
+
+	get_task_struct(thread);
+	wake_up_process(thread);
+
+	return thread;
+}
+qdf_export_symbol(qdf_thread_run);
+
+QDF_STATUS qdf_thread_join(qdf_thread_t *thread)
+{
+	QDF_STATUS status;
+
+	QDF_BUG(thread);
+
+	status = (QDF_STATUS)kthread_stop(thread);
+	put_task_struct(thread);
+
+	return status;
+}
+qdf_export_symbol(qdf_thread_join);
+
+bool qdf_thread_should_stop(void)
+{
+	return kthread_should_stop();
+}
+qdf_export_symbol(qdf_thread_should_stop);
+
 int qdf_wake_up_process(qdf_thread_t *thread)
 {
 	return wake_up_process(thread);