#include <linux/spinlock.h>#include <linux/task_work.h>#include <linux/tracehook.h> inttask_work_add(struct task_struct *task, struct callback_head *twork, bool notify){	struct callback_head *last, *first;	unsigned long flags; 	/*	 * Not inserting the new work if the task has already passed	 * exit_task_work() is the responisbility of callers.	 */	raw_spin_lock_irqsave(&task->pi_lock, flags);	last = task->task_works;	first = last ? last->next : twork;	twork->next = first;	if (last)		last->next = twork;	task->task_works = twork;	raw_spin_unlock_irqrestore(&task->pi_lock, flags); 	/* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */	if (notify)		set_notify_resume(task);	return 0;} struct callback_head *task_work_cancel(struct task_struct *task, task_work_func_t func){	unsigned long flags;	struct callback_head *last, *res = NULL; 	raw_spin_lock_irqsave(&task->pi_lock, flags);	last = task->task_works;	if (last) {		struct callback_head *q = last, *p = q->next;		while (1) {			if (p->func == func) {				q->next = p->next;				if (p == last)					task->task_works = q == p ? NULL : q;				res = p;				break;			}			if (p == last)				break;			q = p;			p = q->next;		}	}	raw_spin_unlock_irqrestore(&task->pi_lock, flags);	return res;} void task_work_run(void){	struct task_struct *task = current;	struct callback_head *p, *q; 	while (1) {		raw_spin_lock_irq(&task->pi_lock);		p = task->task_works;		task->task_works = NULL;		raw_spin_unlock_irq(&task->pi_lock); 		if (unlikely(!p))			return; 		q = p->next; /* head */		p->next = NULL; /* cut it */		while (q) {			p = q->next;			q->func(q);			q = p;		}	}}