1 files changed, 48 insertions, 92 deletions

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 84bbadd4d021..ab7ae57773e1 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -9,27 +9,22 @@
 #include <linux/kthread.h>
 #include <linux/completion.h>
 #include <linux/err.h>
+#include <linux/cpuset.h>
 #include <linux/unistd.h>
 #include <linux/file.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
-#include <trace/sched.h>
-
-#define KTHREAD_NICE_LEVEL (-5)
+#include <trace/events/sched.h>
 
 static DEFINE_SPINLOCK(kthread_create_lock);
 static LIST_HEAD(kthread_create_list);
 struct task_struct *kthreadd_task;
 
-DEFINE_TRACE(sched_kthread_stop);
-DEFINE_TRACE(sched_kthread_stop_ret);
-
 struct kthread_create_info
 {
 	/* Information passed to kthread() from kthreadd. */
 	int (*threadfn)(void *data);
 	void *data;
-	struct completion started;
 
 	/* Result passed back to kthread_create() from kthreadd. */
 	struct task_struct *result;
@@ -38,17 +33,13 @@ 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?
@@ -59,35 +50,35 @@ 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);
-	complete(&create->started);
+	create->result = current;
+	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)
@@ -98,21 +89,8 @@ static void create_kthread(struct kthread_create_info *create)
 	pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
 	if (pid < 0) {
 		create->result = ERR_PTR(pid);
-	} else {
-		struct sched_param param = { .sched_priority = 0 };
-		wait_for_completion(&create->started);
-		read_lock(&tasklist_lock);
-		create->result = find_task_by_pid_ns(pid, &init_pid_ns);
-		read_unlock(&tasklist_lock);
-		/*
-		 * root may have changed our (kthreadd's) priority or CPU mask.
-		 * The kernel thread should not inherit these properties.
-		 */
-		sched_setscheduler(create->result, SCHED_NORMAL, &param);
-		set_user_nice(create->result, KTHREAD_NICE_LEVEL);
-		set_cpus_allowed_ptr(create->result, cpu_all_mask);
+		complete(&create->done);
 	}
-	complete(&create->done);
 }
 
 /**
@@ -143,7 +121,6 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 
 	create.threadfn = threadfn;
 	create.data = data;
-	init_completion(&create.started);
 	init_completion(&create.done);
 
 	spin_lock(&kthread_create_lock);
@@ -154,78 +131,57 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 	wait_for_completion(&create.done);
 
 	if (!IS_ERR(create.result)) {
+		struct sched_param param = { .sched_priority = 0 };
 		va_list args;
+
 		va_start(args, namefmt);
 		vsnprintf(create.result->comm, sizeof(create.result->comm),
 			  namefmt, args);
 		va_end(args);
+		/*
+		 * root may have changed our (kthreadd's) priority or CPU mask.
+		 * The kernel thread should not inherit these properties.
+		 */
+		sched_setscheduler_nocheck(create.result, SCHED_NORMAL, &param);
+		set_cpus_allowed_ptr(create.result, cpu_all_mask);
 	}
 	return create.result;
 }
 EXPORT_SYMBOL(kthread_create);
 
 /**
- * kthread_bind - bind a just-created kthread to a cpu.
- * @k: thread created by kthread_create().
- * @cpu: cpu (might not be online, must be possible) for @k to run on.
- *
- * Description: This function is equivalent to set_cpus_allowed(),
- * except that @cpu doesn't need to be online, and the thread must be
- * stopped (i.e., just returned from kthread_create()).
- */
-void kthread_bind(struct task_struct *k, unsigned int cpu)
-{
-	/* Must have done schedule() in kthread() before we set_task_cpu */
-	if (!wait_task_inactive(k, TASK_UNINTERRUPTIBLE)) {
-		WARN_ON(1);
-		return;
-	}
-	set_task_cpu(k, cpu);
-	k->cpus_allowed = cpumask_of_cpu(cpu);
-	k->rt.nr_cpus_allowed = 1;
-	k->flags |= PF_THREAD_BOUND;
-}
-EXPORT_SYMBOL(kthread_bind);
-
-/**
  * kthread_stop - stop a thread created by kthread_create().
  * @k: thread created by kthread_create().
  *
  * Sets kthread_should_stop() for @k to return true, wakes it, and
- * waits for it to exit.  Your threadfn() must not call do_exit()
- * itself if you use this function!  This can also be called after
- * kthread_create() instead of calling wake_up_process(): the thread
- * will exit without calling threadfn().
+ * waits for it to exit. This can also be called after kthread_create()
+ * instead of calling wake_up_process(): the thread will exit without
+ * calling threadfn().
+ *
+ * If threadfn() may call do_exit() itself, the caller must ensure
+ * task_struct can't go away.
  *
  * Returns the result of threadfn(), or %-EINTR if wake_up_process()
  * was never called.
  */
 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;
@@ -239,8 +195,8 @@ int kthreadd(void *unused)
 	/* Setup a clean context for our children to inherit. */
 	set_task_comm(tsk, "kthreadd");
 	ignore_signals(tsk);
-	set_user_nice(tsk, KTHREAD_NICE_LEVEL);
 	set_cpus_allowed_ptr(tsk, cpu_all_mask);
+	set_mems_allowed(node_possible_map);
 
 	current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;