[PATCH] Add kthread_stop_sem()
Enhance the kthread API by adding kthread_stop_sem, for use in stopping
threads that spend their idle time waiting on a semaphore.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 3fa7864..ebdd41f 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -70,6 +70,18 @@
int kthread_stop(struct task_struct *k);
/**
+ * kthread_stop_sem: stop a thread created by kthread_create().
+ * @k: thread created by kthread_create().
+ * @s: semaphore that @k waits on while idle.
+ *
+ * Does essentially the same thing as kthread_stop() above, but wakes
+ * @k by calling up(@s).
+ *
+ * Returns the result of threadfn(), or -EINTR if wake_up_process()
+ * was never called. */
+int kthread_stop_sem(struct task_struct *k, struct semaphore *s);
+
+/**
* kthread_should_stop: should this kthread return now?
*
* When someone calls kthread_stop on your kthread, it will be woken
diff --git a/kernel/kthread.c b/kernel/kthread.c
index f50f174..e75950a 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -165,6 +165,12 @@
int kthread_stop(struct task_struct *k)
{
+ return kthread_stop_sem(k, NULL);
+}
+EXPORT_SYMBOL(kthread_stop);
+
+int kthread_stop_sem(struct task_struct *k, struct semaphore *s)
+{
int ret;
down(&kthread_stop_lock);
@@ -178,7 +184,10 @@
/* Now set kthread_should_stop() to true, and wake it up. */
kthread_stop_info.k = k;
- wake_up_process(k);
+ if (s)
+ up(s);
+ else
+ wake_up_process(k);
put_task_struct(k);
/* Once it dies, reset stop ptr, gather result and we're done. */
@@ -189,7 +198,7 @@
return ret;
}
-EXPORT_SYMBOL(kthread_stop);
+EXPORT_SYMBOL(kthread_stop_sem);
static __init int helper_init(void)
{