X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fkthread.c;h=eb8751aa0418d448f2b46d364074d39bf622ec6b;hb=8177e6d6dfb9cd03d9bdeb647c32161f8f58f686;hp=e377e2244103b28e383e7fc4c4bee120427c1e68;hpb=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/kthread.c b/kernel/kthread.c
index e377e22..eb8751a 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -1,7 +1,7 @@
 /* Kernel thread helper functions.
  *   Copyright (C) 2004 IBM Corporation, Rusty Russell.
  *
- * Creation is done via keventd, so that we get a clean environment
+ * Creation is done via kthreadd, so that we get a clean environment
  * even if we're invoked from userspace (think modprobe, hotplug cpu,
  * etc.).
  */
@@ -9,194 +9,245 @@
 #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 <asm/semaphore.h>
+#include <linux/mutex.h>
+#include <trace/events/sched.h>
 
-/*
- * We dont want to execute off keventd since it might
- * hold a semaphore our callers hold too:
- */
-static struct workqueue_struct *helper_wq;
+#define KTHREAD_NICE_LEVEL (-5)
+
+static DEFINE_SPINLOCK(kthread_create_lock);
+static LIST_HEAD(kthread_create_list);
+struct task_struct *kthreadd_task;
 
 struct kthread_create_info
 {
-	/* Information passed to kthread() from keventd. */
+	/* Information passed to kthread() from kthreadd. */
 	int (*threadfn)(void *data);
 	void *data;
-	struct completion started;
 
-	/* Result passed back to kthread_create() from keventd. */
+	/* Result passed back to kthread_create() from kthreadd. */
 	struct task_struct *result;
 	struct completion done;
+
+	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 DECLARE_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?
+ *
+ * When someone calls kthread_stop() on your kthread, it will be woken
+ * and this will return true.  You should then return, and your return
+ * value will be passed through to kthread_stop().
+ */
 int kthread_should_stop(void)
 {
-	return (kthread_stop_info.k == current);
+	return to_kthread(current)->should_stop;
 }
 EXPORT_SYMBOL(kthread_should_stop);
 
-static void kthread_exit_files(void)
-{
-	struct fs_struct *fs;
-	struct task_struct *tsk = current;
-
-	exit_fs(tsk);		/* current->fs->count--; */
-	fs = init_task.fs;
-	tsk->fs = fs;
-	atomic_inc(&fs->count);
- 	exit_files(tsk);
-	current->files = init_task.files;
-	atomic_inc(&tsk->files->count);
-}
-
 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;
-	sigset_t blocked;
-	int ret = -EINTR;
-
-	kthread_exit_files();
-
-	/* Copy data: it's on keventd's stack */
-	threadfn = create->threadfn;
-	data = create->data;
-
-	/* Block and flush all signals (in case we're not from keventd). */
-	sigfillset(&blocked);
-	sigprocmask(SIG_BLOCK, &blocked, NULL);
-	flush_signals(current);
+	int (*threadfn)(void *data) = create->threadfn;
+	void *data = create->data;
+	struct kthread self;
+	int ret;
 
-	/* By default we can run anywhere, unlike keventd. */
-	set_cpus_allowed(current, CPU_MASK_ALL);
+	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_INTERRUPTIBLE);
-	complete(&create->started);
+	__set_current_state(TASK_UNINTERRUPTIBLE);
+	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);
 }
 
-/* We are keventd: create a thread. */
-static void keventd_create_kthread(void *_create)
+static void create_kthread(struct kthread_create_info *create)
 {
-	struct kthread_create_info *create = _create;
 	int pid;
 
 	/* We want our own signal handler (we take no signals by default). */
 	pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
 	if (pid < 0) {
 		create->result = ERR_PTR(pid);
-	} else {
-		wait_for_completion(&create->started);
-		create->result = find_task_by_pid(pid);
+		complete(&create->done);
 	}
-	complete(&create->done);
 }
 
+/**
+ * kthread_create - create a kthread.
+ * @threadfn: the function to run until signal_pending(current).
+ * @data: data ptr for @threadfn.
+ * @namefmt: printf-style name for the thread.
+ *
+ * Description: This helper function creates and names a kernel
+ * thread.  The thread will be stopped: use wake_up_process() to start
+ * it.  See also kthread_run(), kthread_create_on_cpu().
+ *
+ * When woken, the thread will run @threadfn() with @data as its
+ * argument. @threadfn() can either call do_exit() directly if it is a
+ * standalone thread for which noone will call kthread_stop(), or
+ * return when 'kthread_should_stop()' is true (which means
+ * kthread_stop() has been called).  The return value should be zero
+ * or a negative error number; it will be passed to kthread_stop().
+ *
+ * Returns a task_struct or ERR_PTR(-ENOMEM).
+ */
 struct task_struct *kthread_create(int (*threadfn)(void *data),
 				   void *data,
 				   const char namefmt[],
 				   ...)
 {
 	struct kthread_create_info create;
-	DECLARE_WORK(work, keventd_create_kthread, &create);
 
 	create.threadfn = threadfn;
 	create.data = data;
-	init_completion(&create.started);
 	init_completion(&create.done);
 
-	/*
-	 * The workqueue needs to start up first:
-	 */
-	if (!helper_wq)
-		work.func(work.data);
-	else {
-		queue_work(helper_wq, &work);
-		wait_for_completion(&create.done);
-	}
+	spin_lock(&kthread_create_lock);
+	list_add_tail(&create.list, &kthread_create_list);
+	spin_unlock(&kthread_create_lock);
+
+	wake_up_process(kthreadd_task);
+	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_user_nice(create.result, KTHREAD_NICE_LEVEL);
+		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)
 {
-	BUG_ON(k->state != TASK_INTERRUPTIBLE);
 	/* Must have done schedule() in kthread() before we set_task_cpu */
-	wait_task_inactive(k);
+	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. 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;
 
-	down(&kthread_stop_lock);
-
-	/* It could exit after stop_info.k set, but before wake_up_process. */
+	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);
-	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;
-	up(&kthread_stop_lock);
+	trace_sched_kthread_stop_ret(ret);
 
 	return ret;
 }
 EXPORT_SYMBOL(kthread_stop);
 
-static __init int helper_init(void)
+int kthreadd(void *unused)
 {
-	helper_wq = create_singlethread_workqueue("kthread");
-	BUG_ON(!helper_wq);
+	struct task_struct *tsk = current;
+
+	/* 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;
+
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (list_empty(&kthread_create_list))
+			schedule();
+		__set_current_state(TASK_RUNNING);
+
+		spin_lock(&kthread_create_lock);
+		while (!list_empty(&kthread_create_list)) {
+			struct kthread_create_info *create;
+
+			create = list_entry(kthread_create_list.next,
+					    struct kthread_create_info, list);
+			list_del_init(&create->list);
+			spin_unlock(&kthread_create_lock);
+
+			create_kthread(create);
+
+			spin_lock(&kthread_create_lock);
+		}
+		spin_unlock(&kthread_create_lock);
+	}
 
 	return 0;
 }
-core_initcall(helper_init);
-