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-rw-r--r--kernel/kthread.c69
1 files changed, 28 insertions, 41 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index bc5d1f0b25a4..9b1a7de26979 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -35,17 +35,13 @@ struct kthread_create_info
struct list_head list;
};
-struct kthread_stop_info
-{
- struct task_struct *k;
- int err;
- struct completion done;
+struct kthread {
+ int should_stop;
+ struct completion exited;
};
-/* Thread stopping is done by setthing this var: lock serializes
- * multiple kthread_stop calls. */
-static DEFINE_MUTEX(kthread_stop_lock);
-static struct kthread_stop_info kthread_stop_info;
+#define to_kthread(tsk) \
+ container_of((tsk)->vfork_done, struct kthread, exited)
/**
* kthread_should_stop - should this kthread return now?
@@ -56,20 +52,22 @@ static struct kthread_stop_info kthread_stop_info;
*/
int kthread_should_stop(void)
{
- return (kthread_stop_info.k == current);
+ return to_kthread(current)->should_stop;
}
EXPORT_SYMBOL(kthread_should_stop);
static int kthread(void *_create)
{
+ /* Copy data: it's on kthread's stack */
struct kthread_create_info *create = _create;
- int (*threadfn)(void *data);
- void *data;
- int ret = -EINTR;
+ int (*threadfn)(void *data) = create->threadfn;
+ void *data = create->data;
+ struct kthread self;
+ int ret;
- /* Copy data: it's on kthread's stack */
- threadfn = create->threadfn;
- data = create->data;
+ self.should_stop = 0;
+ init_completion(&self.exited);
+ current->vfork_done = &self.exited;
/* OK, tell user we're spawned, wait for stop or wakeup */
__set_current_state(TASK_UNINTERRUPTIBLE);
@@ -77,15 +75,12 @@ static int kthread(void *_create)
complete(&create->done);
schedule();
- if (!kthread_should_stop())
+ ret = -EINTR;
+ if (!self.should_stop)
ret = threadfn(data);
- /* It might have exited on its own, w/o kthread_stop. Check. */
- if (kthread_should_stop()) {
- kthread_stop_info.err = ret;
- complete(&kthread_stop_info.done);
- }
- return 0;
+ /* we can't just return, we must preserve "self" on stack */
+ do_exit(ret);
}
static void create_kthread(struct kthread_create_info *create)
@@ -195,30 +190,22 @@ EXPORT_SYMBOL(kthread_bind);
*/
int kthread_stop(struct task_struct *k)
{
+ struct kthread *kthread;
int ret;
- mutex_lock(&kthread_stop_lock);
-
- /* It could exit after stop_info.k set, but before wake_up_process. */
- get_task_struct(k);
-
trace_sched_kthread_stop(k);
+ get_task_struct(k);
- /* Must init completion *before* thread sees kthread_stop_info.k */
- init_completion(&kthread_stop_info.done);
- smp_wmb();
+ kthread = to_kthread(k);
+ barrier(); /* it might have exited */
+ if (k->vfork_done != NULL) {
+ kthread->should_stop = 1;
+ wake_up_process(k);
+ wait_for_completion(&kthread->exited);
+ }
+ ret = k->exit_code;
- /* Now set kthread_should_stop() to true, and wake it up. */
- kthread_stop_info.k = k;
- wake_up_process(k);
put_task_struct(k);
-
- /* Once it dies, reset stop ptr, gather result and we're done. */
- wait_for_completion(&kthread_stop_info.done);
- kthread_stop_info.k = NULL;
- ret = kthread_stop_info.err;
- mutex_unlock(&kthread_stop_lock);
-
trace_sched_kthread_stop_ret(ret);
return ret;