3 files changed, 76 insertions, 56 deletions

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 1c65e7a9f186..00dd957e245b 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -30,4 +30,7 @@ void kthread_bind(struct task_struct *k, unsigned int cpu);
 int kthread_stop(struct task_struct *k);
 int kthread_should_stop(void);
 
+int kthreadd(void *unused);
+extern struct task_struct *kthreadd_task;
+
 #endif /* _LINUX_KTHREAD_H */
diff --git a/init/main.c b/init/main.c
index c1537e0ddceb..e8d080cab443 100644
--- a/init/main.c
+++ b/init/main.c
@@ -54,6 +54,7 @@
 #include <linux/lockdep.h>
 #include <linux/pid_namespace.h>
 #include <linux/device.h>
+#include <linux/kthread.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -425,8 +426,12 @@ static void __init setup_command_line(char *command_line)
 static void noinline rest_init(void)
         __releases(kernel_lock)
 {
+        int pid;
+
         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
         numa_default_policy();
+        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
+        kthreadd_task = find_task_by_pid(pid);
         unlock_kernel();
 
         /*
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 87c50ccd1d4e..0eb0070a3c57 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.).
  */
@@ -15,24 +15,22 @@
 #include <linux/mutex.h>
 #include <asm/semaphore.h>
 
-/*
- * We dont want to execute off keventd since it might
- * hold a semaphore our callers hold too:
- */
-static struct workqueue_struct *helper_wq;
+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 work_struct work;
+        struct list_head list;
 };
 
 struct kthread_stop_info
@@ -60,42 +58,17 @@ int kthread_should_stop(void)
 }
 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)
 {
         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 */
+        /* Copy data: it's on kthread'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);
-
-        /* By default we can run anywhere, unlike keventd. */
-        set_cpus_allowed(current, CPU_MASK_ALL);
-
         /* OK, tell user we're spawned, wait for stop or wakeup */
         __set_current_state(TASK_INTERRUPTIBLE);
         complete(&create->started);
@@ -112,11 +85,8 @@ static int kthread(void *_create)
         return 0;
 }
 
-/* We are keventd: create a thread. */
-static void keventd_create_kthread(struct work_struct *work)
+static void create_kthread(struct kthread_create_info *create)
 {
-        struct kthread_create_info *create =
-                container_of(work, struct kthread_create_info, work);
         int pid;
 
         /* We want our own signal handler (we take no signals by default). */
@@ -162,17 +132,14 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
         create.data = data;
         init_completion(&create.started);
         init_completion(&create.done);
-        INIT_WORK(&create.work, keventd_create_kthread);
-
-        /*
-         * The workqueue needs to start up first:
-         */
-        if (!helper_wq)
-                create.work.func(&create.work);
-        else {
-                queue_work(helper_wq, &create.work);
-                wait_for_completion(&create.done);
-        }
+
+        spin_lock(&kthread_create_lock);
+        list_add_tail(&create.list, &kthread_create_list);
+        wake_up_process(kthreadd_task);
+        spin_unlock(&kthread_create_lock);
+
+        wait_for_completion(&create.done);
+
         if (!IS_ERR(create.result)) {
                 va_list args;
                 va_start(args, namefmt);
@@ -180,7 +147,6 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
                           namefmt, args);
                 va_end(args);
         }
-
         return create.result;
 }
 EXPORT_SYMBOL(kthread_create);
@@ -245,12 +211,58 @@ int kthread_stop(struct task_struct *k)
 }
 EXPORT_SYMBOL(kthread_stop);
 
-static __init int helper_init(void)
+
+static __init void kthreadd_setup(void)
 {
-        helper_wq = create_singlethread_workqueue("kthread");
-        BUG_ON(!helper_wq);
+        struct task_struct *tsk = current;
+        struct k_sigaction sa;
+        sigset_t blocked;
 
-        return 0;
+        set_task_comm(tsk, "kthreadd");
+
+        /* Block and flush all signals */
+        sigfillset(&blocked);
+        sigprocmask(SIG_BLOCK, &blocked, NULL);
+        flush_signals(tsk);
+
+        /* SIG_IGN makes children autoreap: see do_notify_parent(). */
+        sa.sa.sa_handler = SIG_IGN;
+        sa.sa.sa_flags = 0;
+        siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
+        do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
+
+        set_user_nice(current, -5);
+        set_cpus_allowed(current, CPU_MASK_ALL);
 }
 
-core_initcall(helper_init);
+int kthreadd(void *unused)
+{
+        /* Setup a clean context for our children to inherit. */
+        kthreadd_setup();
+
+        current->flags |= PF_NOFREEZE;
+
+        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;
+}