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Commit f4efdd65 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus 

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  work_on_cpu(): rewrite it to create a kernel thread on demand
  kthread: move sched-realeted initialization from kthreadd context
  kthread: Don't looking for a task in create_kthread() #2
parents d8312204 6b44003e

kernel/kthread.c

+12 −14
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ static int kthread(void *_create) 


	/* OK, tell user we're spawned, wait for stop or wakeup */

	__set_current_state(TASK_UNINTERRUPTIBLE);

	create->result = current;

	complete(&create->started);

	schedule();
@@ -96,22 +97,10 @@ static void create_kthread(struct kthread_create_info *create) 


	/* 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) {

	if (pid < 0)

		create->result = ERR_PTR(pid);

	} else {

		struct sched_param param = { .sched_priority = 0 };

	else

		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);

}
@@ -154,11 +143,20 @@ 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_user_nice(create.result, KTHREAD_NICE_LEVEL);

		set_cpus_allowed_ptr(create.result, cpu_all_mask);

	}

	return create.result;

}

kernel/workqueue.c

+19 −17
Original line number Diff line number Diff line
@@ -966,20 +966,20 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 
}



#ifdef CONFIG_SMP

static struct workqueue_struct *work_on_cpu_wq __read_mostly;



struct work_for_cpu {

	struct work_struct work;

	struct completion completion;

	long (*fn)(void *);

	void *arg;

	long ret;

};



static void do_work_for_cpu(struct work_struct *w)

static int do_work_for_cpu(void *_wfc)

{

	struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work);



	struct work_for_cpu *wfc = _wfc;

	wfc->ret = wfc->fn(wfc->arg);

	complete(&wfc->completion);

	return 0;

}



/**
@@ -990,17 +990,23 @@ static void do_work_for_cpu(struct work_struct *w) 
 *

 * This will return the value @fn returns.

 * It is up to the caller to ensure that the cpu doesn't go offline.

 * The caller must not hold any locks which would prevent @fn from completing.

 */

long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)

{

	struct work_for_cpu wfc;



	INIT_WORK(&wfc.work, do_work_for_cpu);

	wfc.fn = fn;

	wfc.arg = arg;

	queue_work_on(cpu, work_on_cpu_wq, &wfc.work);

	flush_work(&wfc.work);

	struct task_struct *sub_thread;

	struct work_for_cpu wfc = {

		.completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),

		.fn = fn,

		.arg = arg,

	};



	sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");

	if (IS_ERR(sub_thread))

		return PTR_ERR(sub_thread);

	kthread_bind(sub_thread, cpu);

	wake_up_process(sub_thread);

	wait_for_completion(&wfc.completion);

	return wfc.ret;

}

EXPORT_SYMBOL_GPL(work_on_cpu);
@@ -1016,8 +1022,4 @@ void __init init_workqueues(void) 
	hotcpu_notifier(workqueue_cpu_callback, 0);

	keventd_wq = create_workqueue("events");

	BUG_ON(!keventd_wq);

#ifdef CONFIG_SMP

	work_on_cpu_wq = create_workqueue("work_on_cpu");

	BUG_ON(!work_on_cpu_wq);

#endif

}