t = next_thread(t);		} while (t != p);		break;	}}static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now){	/*	 * That's all for this thread or process.	 * We leave our residual in expires to be reported.	 */	put_task_struct(timer->it.cpu.task);	timer->it.cpu.task = NULL;	timer->it.cpu.expires = cpu_time_sub(timer->it_clock,					     timer->it.cpu.expires,					     now);}/* * Insert the timer on the appropriate list before any timers that * expire later.  This must be called with the tasklist_lock held * for reading, and interrupts disabled. */static void arm_timer(struct k_itimer *timer, union cpu_time_count now){	struct task_struct *p = timer->it.cpu.task;	struct list_head *head, *listpos;	struct cpu_timer_list *const nt = &timer->it.cpu;	struct cpu_timer_list *next;	unsigned long i;	head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?		p->cpu_timers : p->signal->cpu_timers);	head += CPUCLOCK_WHICH(timer->it_clock);	BUG_ON(!irqs_disabled());	spin_lock(&p->sighand->siglock);	listpos = head;	if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {		list_for_each_entry(next, head, entry) {			if (next->expires.sched > nt->expires.sched)				break;			listpos = &next->entry;		}	} else {		list_for_each_entry(next, head, entry) {			if (cputime_gt(next->expires.cpu, nt->expires.cpu))				break;			listpos = &next->entry;		}	}	list_add(&nt->entry, listpos);	if (listpos == head) {		/*		 * We are the new earliest-expiring timer.		 * If we are a thread timer, there can always		 * be a process timer telling us to stop earlier.		 */		if (CPUCLOCK_PERTHREAD(timer->it_clock)) {			switch (CPUCLOCK_WHICH(timer->it_clock)) {			default:				BUG();			case CPUCLOCK_PROF:				if (cputime_eq(p->it_prof_expires,					       cputime_zero) ||				    cputime_gt(p->it_prof_expires,					       nt->expires.cpu))					p->it_prof_expires = nt->expires.cpu;				break;			case CPUCLOCK_VIRT:				if (cputime_eq(p->it_virt_expires,					       cputime_zero) ||				    cputime_gt(p->it_virt_expires,					       nt->expires.cpu))					p->it_virt_expires = nt->expires.cpu;				break;			case CPUCLOCK_SCHED:				if (p->it_sched_expires == 0 ||				    p->it_sched_expires > nt->expires.sched)					p->it_sched_expires = nt->expires.sched;				break;			}		} else {			/*			 * For a process timer, we must balance			 * all the live threads' expirations.			 */			switch (CPUCLOCK_WHICH(timer->it_clock)) {			default:				BUG();			case CPUCLOCK_VIRT:				if (!cputime_eq(p->signal->it_virt_expires,						cputime_zero) &&				    cputime_lt(p->signal->it_virt_expires,					       timer->it.cpu.expires.cpu))					break;				goto rebalance;			case CPUCLOCK_PROF:				if (!cputime_eq(p->signal->it_prof_expires,						cputime_zero) &&				    cputime_lt(p->signal->it_prof_expires,					       timer->it.cpu.expires.cpu))					break;				i = p->signal->rlim[RLIMIT_CPU].rlim_cur;				if (i != RLIM_INFINITY &&				    i <= cputime_to_secs(timer->it.cpu.expires.cpu))					break;				goto rebalance;			case CPUCLOCK_SCHED:			rebalance:				process_timer_rebalance(					timer->it.cpu.task,					CPUCLOCK_WHICH(timer->it_clock),					timer->it.cpu.expires, now);				break;			}		}	}	spin_unlock(&p->sighand->siglock);}/* * The timer is locked, fire it and arrange for its reload. */static void cpu_timer_fire(struct k_itimer *timer){	if (unlikely(timer->sigq == NULL)) {		/*		 * This a special case for clock_nanosleep,		 * not a normal timer from sys_timer_create.		 */		wake_up_process(timer->it_process);		timer->it.cpu.expires.sched = 0;	} else if (timer->it.cpu.incr.sched == 0) {		/*		 * One-shot timer.  Clear it as soon as it's fired.		 */		posix_timer_event(timer, 0);		timer->it.cpu.expires.sched = 0;	} else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {		/*		 * The signal did not get queued because the signal		 * was ignored, so we won't get any callback to		 * reload the timer.  But we need to keep it		 * ticking in case the signal is deliverable next time.		 */		posix_cpu_timer_schedule(timer);	}}/* * Guts of sys_timer_settime for CPU timers. * This is called with the timer locked and interrupts disabled. * If we return TIMER_RETRY, it's necessary to release the timer's lock * and try again.  (This happens when the timer is in the middle of firing.) */int posix_cpu_timer_set(struct k_itimer *timer, int flags,			struct itimerspec *new, struct itimerspec *old){	struct task_struct *p = timer->it.cpu.task;	union cpu_time_count old_expires, new_expires, val;	int ret;	if (unlikely(p == NULL)) {		/*		 * Timer refers to a dead task's clock.		 */		return -ESRCH;	}	new_expires = timespec_to_sample(timer->it_clock, &new->it_value);	read_lock(&tasklist_lock);	/*	 * We need the tasklist_lock to protect against reaping that	 * clears p->signal.  If p has just been reaped, we can no	 * longer get any information about it at all.	 */	if (unlikely(p->signal == NULL)) {		read_unlock(&tasklist_lock);		put_task_struct(p);		timer->it.cpu.task = NULL;		return -ESRCH;	}	/*	 * Disarm any old timer after extracting its expiry time.	 */	BUG_ON(!irqs_disabled());	ret = 0;	spin_lock(&p->sighand->siglock);	old_expires = timer->it.cpu.expires;	if (unlikely(timer->it.cpu.firing)) {		timer->it.cpu.firing = -1;		ret = TIMER_RETRY;	} else		list_del_init(&timer->it.cpu.entry);	spin_unlock(&p->sighand->siglock);	/*	 * We need to sample the current value to convert the new	 * value from to relative and absolute, and to convert the	 * old value from absolute to relative.  To set a process	 * timer, we need a sample to balance the thread expiry	 * times (in arm_timer).  With an absolute time, we must	 * check if it's already passed.  In short, we need a sample.	 */	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {		cpu_clock_sample(timer->it_clock, p, &val);	} else {		cpu_clock_sample_group(timer->it_clock, p, &val);	}	if (old) {		if (old_expires.sched == 0) {			old->it_value.tv_sec = 0;			old->it_value.tv_nsec = 0;		} else {			/*			 * Update the timer in case it has			 * overrun already.  If it has,			 * we'll report it as having overrun			 * and with the next reloaded timer			 * already ticking, though we are			 * swallowing that pending			 * notification here to install the			 * new setting.			 */			bump_cpu_timer(timer, val);			if (cpu_time_before(timer->it_clock, val,					    timer->it.cpu.expires)) {				old_expires = cpu_time_sub(					timer->it_clock,					timer->it.cpu.expires, val);				sample_to_timespec(timer->it_clock,						   old_expires,						   &old->it_value);			} else {				old->it_value.tv_nsec = 1;				old->it_value.tv_sec = 0;			}		}	}	if (unlikely(ret)) {		/*		 * We are colliding with the timer actually firing.		 * Punt after filling in the timer's old value, and		 * disable this firing since we are already reporting		 * it as an overrun (thanks to bump_cpu_timer above).		 */		read_unlock(&tasklist_lock);		goto out;	}	if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {		cpu_time_add(timer->it_clock, &new_expires, val);	}	/*	 * Install the new expiry time (or zero).	 * For a timer with no notification action, we don't actually	 * arm the timer (we'll just fake it for timer_gettime).	 */	timer->it.cpu.expires = new_expires;	if (new_expires.sched != 0 &&	    (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&	    cpu_time_before(timer->it_clock, val, new_expires)) {		arm_timer(timer, val);	}	read_unlock(&tasklist_lock);	/*	 * Install the new reload setting, and	 * set up the signal and overrun bookkeeping.	 */	timer->it.cpu.incr = timespec_to_sample(timer->it_clock,						&new->it_interval);	/*	 * This acts as a modification timestamp for the timer,	 * so any automatic reload attempt will punt on seeing	 * that we have reset the timer manually.	 */	timer->it_requeue_pending = (timer->it_requeue_pending + 2) &		~REQUEUE_PENDING;	timer->it_overrun_last = 0;	timer->it_overrun = -1;	if (new_expires.sched != 0 &&	    (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&	    !cpu_time_before(timer->it_clock, val, new_expires)) {		/*		 * The designated time already passed, so we notify		 * immediately, even if the thread never runs to		 * accumulate more time on this clock.		 */		cpu_timer_fire(timer);	}	ret = 0; out:	if (old) {		sample_to_timespec(timer->it_clock,				   timer->it.cpu.incr, &old->it_interval);	}	return ret;}void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp){	union cpu_time_count now;	struct task_struct *p = timer->it.cpu.task;	int clear_dead;	/*	 * Easy part: convert the reload time.	 */	sample_to_timespec(timer->it_clock,			   timer->it.cpu.incr, &itp->it_interval);	if (timer->it.cpu.expires.sched == 0) {	/* Timer not armed at all.  */		itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;		return;	}	if (unlikely(p == NULL)) {		/*		 * This task already died and the timer will never fire.		 * In this case, expires is actually the dead value.		 */	dead:		sample_to_timespec(timer->it_clock, timer->it.cpu.expires,				   &itp->it_value);		return;	}	/*	 * Sample the clock to take the difference with the expiry time.	 */	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {		cpu_clock_sample(timer->it_clock, p, &now);		clear_dead = p->exit_state;	} else {		read_lock(&tasklist_lock);		if (unlikely(p->signal == NULL)) {			/*			 * The process has been reaped.			 * We can't even collect a sample any more.			 * Call the timer disarmed, nothing else to do.			 */			put_task_struct(p);			timer->it.cpu.task = NULL;			timer->it.cpu.expires.sched = 0;			read_unlock(&tasklist_lock);			goto dead;		} else {			cpu_clock_sample_group(timer->it_clock, p, &now);			clear_dead = (unlikely(p->exit_state) &&				      thread_group_empty(p));		}		read_unlock(&tasklist_lock);	}	if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {		if (timer->it.cpu.incr.sched == 0 &&		    cpu_time_before(timer->it_clock,				    timer->it.cpu.expires, now)) {			/*			 * Do-nothing timer expired and has no reload,			 * so it's as if it was never set.			 */			timer->it.cpu.expires.sched = 0;			itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;			return;		}		/*		 * Account for any expirations and reloads that should		 * have happened.		 */		bump_cpu_timer(timer, now);	}	if (unlikely(clear_dead)) {		/*		 * We've noticed that the thread is dead, but		 * not yet reaped.  Take this opportunity to		 * drop our task ref.		 */		clear_dead_task(timer, now);		goto dead;	}	if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {		sample_to_timespec(timer->it_clock,				   cpu_time_sub(timer->it_clock,						timer->it.cpu.expires, now),				   &itp->it_value);	} else {		/*		 * The timer should have expired already, but the firing		 * hasn't taken place yet.  Say it's just about to expire.		 */		itp->it_value.tv_nsec = 1;		itp->it_value.tv_sec = 0;	}}/* * Check for any per-thread CPU timers that have fired and move them off * the tsk->cpu_timers[N] list onto the firing list.  Here we update the * tsk->it_*_expires values to reflect the remaining thread CPU timers. */static void check_thread_timers(struct task_struct *tsk,				struct list_head *firing){	int maxfire;	struct list_head *timers = tsk->cpu_timers;	maxfire = 20;	tsk->it_prof_expires = cputime_zero;	while (!list_empty(timers)) {		struct cpu_timer_list *t = list_first_entry(timers,						      struct cpu_timer_list,						      entry);		if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {			tsk->it_prof_expires = t->expires.cpu;			break;		}		t->firing = 1;		list_move_tail(&t->entry, firing);	}	++timers;	maxfire = 20;	tsk->it_virt_expires = cputime_zero;	while (!list_empty(timers)) {		struct cpu_timer_list *t = list_first_entry(timers,						      struct cpu_timer_list,						      entry);		if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {			tsk->it_virt_expires = t->expires.cpu;			break;		}		t->firing = 1;		list_move_tail(&t->entry, firing);	}	++timers;	maxfire = 20;	tsk->it_sched_expires = 0;	while (!list_empty(timers)) {		struct cpu_timer_list *t = list_first_entry(timers,						      struct cpu_timer_list,						      entry);		if (!--maxfire || tsk->sched_time < t->expires.sched) {			tsk->it_sched_expires = t->expires.sched;			break;		}		t->firing = 1;		list_move_tail(&t->entry, firing);	}}/* * Check for any per-thread CPU timers that have fired and move them * off the tsk->*_timers list onto the firing list.  Per-thread timers * have already been taken off. */static void check_process_timers(struct task_struct *tsk,				 struct list_head *firing){	int maxfire;	struct signal_struct *const sig = tsk->signal;	cputime_t utime, stime, ptime, virt_expires, prof_expires;	unsigned long long sched_time, sched_expires;	struct task_struct *t;	struct list_head *timers = sig->cpu_timers;	/*	 * Don't sample the current process CPU clocks if there are no timers.	 */	if (list_empty(&timers[CPUCLOCK_PROF]) &&	    cputime_eq(sig->it_prof_expires, cputime_zero) &&	    sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&	    list_empty(&timers[CPUCLOCK_VIRT]) &&	    cputime_eq(sig->it_virt_expires, cputime_zero) &&	    list_empty(&timers[CPUCLOCK_SCHED]))		return;	/*	 * Collect the current process totals.	 */	utime = sig->utime;	stime = sig->stime;	sched_time = sig->sched_time;	t = tsk;	do {		utime = cputime_add(utime, t->utime);		stime = cputime_add(stime, t->stime);		sched_time += t->sched_time;		t = next_thread(t);	} while (t != tsk);	ptime = cputime_add(utime, stime);	maxfire = 20;	prof_expires = cputime_zero;	while (!list_empty(timers)) {		struct cpu_timer_list *t = list_first_entry(timers,						      struct cpu_timer_list,						      entry);		if (!--maxfire || cputime_lt(ptime, t->expires.cpu)) {			prof_expires = t->expires.cpu;			break;		}		t->firing = 1;		list_move_tail(&t->entry, firing);	}	++timers;	maxfire = 20;	virt_expires = cputime_zero;	while (!list_empty(timers)) {		struct cpu_timer_list *t = list_first_entry(timers,						      struct cpu_timer_list,						      entry);		if (!--maxfire || cputime_lt(utime, t->expires.cpu)) {			virt_expires = t->expires.cpu;			break;		}		t->firing = 1;		list_move_tail(&t->entry, firing);	}	++timers;	maxfire = 20;	sched_expires = 0;