USB: usbatm: convert heavy init dances to kthread API

This is an attempt to kill two birds with one stone.

First, we kill one more user of kernel_thread, which is scheduled
for removal. Second - we kill one of the last users of kill_proc -
the function which is also to be removed, because it uses a pid_t
which is not safe now.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Duncan Sands <baldrick@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/atm/usbatm.c

@@ -80,6 +80,7 @@
 #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);
@@ -1014,10 +1015,7 @@ 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);
@@ -1026,7 +1024,7 @@ static int usbatm_do_heavy_init(void *arg)
 		ret = usbatm_atm_init(instance);
 
 	mutex_lock(&instance->serialize);
-	instance->thread_pid = -1;
+	instance->thread = NULL;
 	mutex_unlock(&instance->serialize);
 
 	complete_and_exit(&instance->thread_exited, ret);
@@ -1034,13 +1032,18 @@ static int usbatm_do_heavy_init(void *arg)
 
 static int usbatm_heavy_init(struct usbatm_data *instance)
 {
-	int ret = kernel_thread(usbatm_do_heavy_init, instance, CLONE_FS | CLONE_FILES);
+	struct task_struct *t;
 
-	if (ret < 0) {
-		usb_err(instance, "%s: failed to create kernel_thread (%d)!\n", __func__, ret);
-		return ret;
+	t = kthread_create(usbatm_do_heavy_init, instance,
+			instance->driver->driver_name);
+	if (IS_ERR(t)) {
+		usb_err(instance, "%s: failed to create kernel_thread (%ld)!\n",
+				__func__, PTR_ERR(t));
+		return PTR_ERR(t);
 	}
 
+	instance->thread = t;
+	wake_up_process(t);
 	wait_for_completion(&instance->thread_started);
 
 	return 0;
@@ -1124,7 +1127,7 @@ 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;
+	instance->thread = NULL;
 	init_completion(&instance->thread_started);
 	init_completion(&instance->thread_exited);
 
@@ -1287,8 +1290,8 @@ 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);
+	if (instance->thread != NULL)
+		send_sig(SIGTERM, instance->thread, 1);
 	mutex_unlock(&instance->serialize);
 
 	wait_for_completion(&instance->thread_exited);

drivers/usb/atm/usbatm.h

@@ -175,7 +175,7 @@ struct usbatm_data {
 	int disconnected;
 
 	/* heavy init */
-	int thread_pid;
+	struct task_struct *thread;
 	struct completion thread_started;
 	struct completion thread_exited;