[Devel] [PATCH] usbatm: Update to use the kthread api.

[Eric W. Biederman]

During driver initialization if the driver has an expensive
initialization routine usbatm starts a separate kernel thread for it.

In the driver cleanup routine the code waits to ensure the
initialization routine has finished.

Switching to the kthread api allowed some of the thread management
code to be removed.

In addition the kill_proc(SIGTERM, ...) in usbatm_usb_disconnect was
removed because it was absolutely pointless.  The kernel thread did
not handle SIGTERM or any pending signals, so despite marking the
signal as pending it would never have been handled. 

Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
---
 drivers/usb/atm/usbatm.c |   24 ++++++------------------
 drivers/usb/atm/usbatm.h |    2 --
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/drivers/usb/atm/usbatm.c b/drivers/usb/atm/usbatm.c
index ec63b0e..e6cd5e4 100644
--- a/drivers/usb/atm/usbatm.c
+++ b/drivers/usb/atm/usbatm.c
@@ -81,6 +81,7 @@
 #include <linux/stat.h>
 #include <linux/timer.h>
 #include <linux/wait.h>
+#include <linux/kthread.h>
 
 #ifdef VERBOSE_DEBUG
 static int usbatm_print_packet(const unsigned char *data, int len);
@@ -999,35 +1000,26 @@ static int usbatm_do_heavy_init(void *arg)
 	struct usbatm_data *instance = arg;
 	int ret;
 
-	daemonize(instance->driver->driver_name);
-	allow_signal(SIGTERM);
-	instance->thread_pid = current->pid;
-
-	complete(&instance->thread_started);
-
 	ret = instance->driver->heavy_init(instance, instance->usb_intf);
 
 	if (!ret)
 		ret = usbatm_atm_init(instance);
 
-	mutex_lock(&instance->serialize);
-	instance->thread_pid = -1;
-	mutex_unlock(&instance->serialize);
 
 	complete_and_exit(&instance->thread_exited, ret);
 }
 
 static int usbatm_heavy_init(struct usbatm_data *instance)
 {
-	int ret = kernel_thread(usbatm_do_heavy_init, instance, CLONE_KERNEL);
-
-	if (ret < 0) {
+	struct task_struct *thread;
+	thread = kthread_run(usbatm_do_heavy_init, instance,
+				instance->driver->driver_name);
+	if (IS_ERR(thread)) {
+		int ret = PTR_ERR(thread);
 		usb_err(instance, "%s: failed to create kernel_thread (%d)!\n", __func__, ret);
 		return ret;
 	}
 
-	wait_for_completion(&instance->thread_started);
-
 	return 0;
 }
 
@@ -1109,8 +1101,6 @@ int usbatm_usb_probe(struct usb_interface *intf, const struct usb_device_id *id,
 	kref_init(&instance->refcount);		/* dropped in usbatm_usb_disconnect */
 	mutex_init(&instance->serialize);
 
-	instance->thread_pid = -1;
-	init_completion(&instance->thread_started);
 	init_completion(&instance->thread_exited);
 
 	INIT_LIST_HEAD(&instance->vcc_list);
@@ -1272,8 +1262,6 @@ void usbatm_usb_disconnect(struct usb_interface *intf)
 
 	mutex_lock(&instance->serialize);
 	instance->disconnected = 1;
-	if (instance->thread_pid >= 0)
-		kill_proc(instance->thread_pid, SIGTERM, 1);
 	mutex_unlock(&instance->serialize);
 
 	wait_for_completion(&instance->thread_exited);
diff --git a/drivers/usb/atm/usbatm.h b/drivers/usb/atm/usbatm.h
index ff8551e..ab42355 100644
--- a/drivers/usb/atm/usbatm.h
+++ b/drivers/usb/atm/usbatm.h
@@ -176,8 +176,6 @@ struct usbatm_data {
 	int disconnected;
 
 	/* heavy init */
-	int thread_pid;
-	struct completion thread_started;
 	struct completion thread_exited;
 
 	/* ATM device */
-- 
1.4.4.1.g278f

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