[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>

1 files changed, 11 insertions, 2 deletions

diff --git a/kernel/kthread.c b/kernel/kthread.c
index f50f174e92da..e75950a1092c 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -165,6 +165,12 @@ EXPORT_SYMBOL(kthread_bind);
 
 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 @@ int kthread_stop(struct task_struct *k)
 
         /* 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 @@ int kthread_stop(struct task_struct *k)
 
         return ret;
 }
-EXPORT_SYMBOL(kthread_stop);
+EXPORT_SYMBOL(kthread_stop_sem);
 
 static __init int helper_init(void)
 {