kthread_stop never returns
Roman Kagan
rkagan at mail.ru
Fri Jan 28 00:46:03 EST 2005
Hi Duncan,
On Thu, Jan 27, 2005 at 06:03:49PM +0100, Duncan Sands wrote:
> On Thursday 27 January 2005 11:12, Duncan Sands wrote:
> > it seems that kthreads are supposed to run forever, and *only* exit when
> > kthread_should_stop is true. This is not what we want. I'll have to try
> > again...
>
> It seems easy to fix. Unfortunately work just got busy again, hopefully
> I can do it all tomorrow (promise!).
Sorta this? (Just got up too early today :)
Compile- and briefly run-tested, including disconnects (both during the
heavy_init and after it has exited) and module unloading.
Cheers,
Roman.
diff -u usbatm.h usbatm.h
--- usbatm.h 27 Jan 2005 13:08:35 -0000
+++ usbatm.h 28 Jan 2005 05:35:49 -0000
@@ -26,6 +26,7 @@
#include <linux/config.h>
#include <linux/list.h>
+#include <linux/completion.h>
#include <linux/kref.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
@@ -158,7 +159,7 @@
void *driver_data;
/* heavy thread part */
- struct task_struct *kthread;
+ struct completion heavy_init_completion;
/* USB device part */
struct usb_device *usb_dev;
diff -u usbatm2.c usbatm2.c
--- usbatm2.c 27 Jan 2005 13:08:35 -0000
+++ usbatm2.c 28 Jan 2005 05:35:49 -0000
@@ -1020,30 +1020,30 @@
struct usbatm_data *instance = arg;
int ret;
+ daemonize("%s/%s", usbatm_driver_name, instance->driver->driver_name);
+
ret = instance->driver->heavy_init(instance, instance->usb_intf);
if (!ret)
ret = usbatm_atm_init(instance);
+ complete(&instance->heavy_init_completion);
+
return ret;
}
-static long usbatm_heavy_init(struct usbatm_data *instance)
+static int usbatm_heavy_init(struct usbatm_data *instance)
{
- struct task_struct *kthread;
+ int ret = kernel_thread(usbatm_do_heavy_init, instance, CLONE_FS | CLONE_FILES);
- kthread = kthread_create(usbatm_do_heavy_init, instance, "%s/%s", usbatm_driver_name, instance->driver->driver_name);
+ if (ret >= 0)
+ return 0;
- if (IS_ERR(kthread)) {
- dbg("usbatm_heavy_init: kernel_thread failed (%ld)!", PTR_ERR(kthread));
- return PTR_ERR(kthread);
- }
+ dbg("usbatm_heavy_init: kernel_thread failed (%d)!", ret);
- instance->kthread = kthread;
- mb();
- wake_up_process(kthread);
+ complete(&instance->heavy_init_completion);
- return 0;
+ return ret;
}
static rwlock_t usbatm_driver_list_lock = RW_LOCK_UNLOCKED;
@@ -1084,6 +1084,8 @@
kref_init(&instance->refcount); /* one for USB */
+ init_completion(&instance->heavy_init_completion);
+
init_MUTEX(&instance->serialize);
instance->driver = driver;
@@ -1200,8 +1202,11 @@
if (need_heavy && driver->heavy_init)
error = usbatm_heavy_init(instance);
- else
+ else {
+ /* pretend that heavy_init was run */
+ complete(&instance->heavy_init_completion);
error = usbatm_atm_init(instance);
+ }
if (error)
goto fail;
@@ -1251,8 +1256,8 @@
if (instance->atm_dev && instance->driver->atm_stop)
instance->driver->atm_stop(instance, instance->atm_dev);
- if (instance->kthread)
- kthread_stop(instance->kthread);
+ /* hope heavy_init has already exited or will do so real soon */
+ wait_for_completion(&instance->heavy_init_completion);
if (instance->driver->unbind)
instance->driver->unbind(instance, intf);
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