C++ clear_thread_flag函数代码示例

void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
{
#ifdef DEBUG_SIG
	printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
	       thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current)); 
#endif
	       
	/* Pending single-step? */
	if (thread_info_flags & _TIF_SINGLESTEP) {
		regs->eflags |= TF_MASK;
		clear_thread_flag(TIF_SINGLESTEP);
	}

	/* deal with pending signal delivery */
	if (thread_info_flags & _TIF_SIGPENDING)
		do_signal(regs,oldset);
}

static inline void poll_idle(void)
{
	int oldval;

	local_irq_enable();

	oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);

	if (!oldval) {
		set_thread_flag(TIF_POLLING_NRFLAG);
		while (!need_resched())
			cpu_relax();
		clear_thread_flag(TIF_POLLING_NRFLAG);
	} else {
		set_need_resched();
	}
}

void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
{
    user_exit();

    if (thread_info_flags & _TIF_UPROBE)
        uprobe_notify_resume(regs);

    if (thread_info_flags & _TIF_SIGPENDING)
        do_signal(regs);

    if (thread_info_flags & _TIF_NOTIFY_RESUME) {
        clear_thread_flag(TIF_NOTIFY_RESUME);
        tracehook_notify_resume(regs);
    }

    user_enter();
}

static void pseries_dedicated_idle_sleep(void)
{ 
	unsigned int cpu = smp_processor_id();
	unsigned long start_snooze;

	/*
	 * Indicate to the HV that we are idle. Now would be
	 * a good time to find other work to dispatch.
	 */
	get_lppaca()->idle = 1;
	get_lppaca()->donate_dedicated_cpu = 1;

	/*
	 * We come in with interrupts disabled, and need_resched()
	 * has been checked recently.  If we should poll for a little
	 * while, do so.
	 */
	if (__get_cpu_var(smt_snooze_delay)) {
		start_snooze = get_tb() +
			__get_cpu_var(smt_snooze_delay) * tb_ticks_per_usec;
		local_irq_enable();
		set_thread_flag(TIF_POLLING_NRFLAG);

		while (get_tb() < start_snooze) {
			if (need_resched() || cpu_is_offline(cpu))
				goto out;
			ppc64_runlatch_off();
			HMT_low();
			HMT_very_low();
		}

		HMT_medium();
		clear_thread_flag(TIF_POLLING_NRFLAG);
		smp_mb();
		local_irq_disable();
		if (need_resched() || cpu_is_offline(cpu))
			goto out;
	}

	cede_processor();

out:
	HMT_medium();
	get_lppaca()->donate_dedicated_cpu = 0;
	get_lppaca()->idle = 0;
}

/*
 * The body of the idle task.
 */
void cpu_idle(void)
{
	if (ppc_md.idle_loop)
		ppc_md.idle_loop();	/* doesn't return */

	set_thread_flag(TIF_POLLING_NRFLAG);
	while (1) {
		while (!need_resched() && !cpu_should_die()) {
			ppc64_runlatch_off();

			if (ppc_md.power_save) {
				clear_thread_flag(TIF_POLLING_NRFLAG);
				/*
				 * smp_mb is so clearing of TIF_POLLING_NRFLAG
				 * is ordered w.r.t. need_resched() test.
				 */
				smp_mb();
				local_irq_disable();

				/* check again after disabling irqs */
				if (!need_resched() && !cpu_should_die())
					ppc_md.power_save();

				local_irq_enable();
				set_thread_flag(TIF_POLLING_NRFLAG);

			} else {
				/*
				 * Go into low thread priority and possibly
				 * low power mode.
				 */
				HMT_low();
				HMT_very_low();
			}
		}

		HMT_medium();
		ppc64_runlatch_on();
		if (cpu_should_die())
			cpu_die();
		preempt_enable_no_resched();
		schedule();
		preempt_disable();
	}
}

/*
 * notification of userspace execution resumption
 * - triggered by the TIF_WORK_MASK flags
 */
asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
	__u32 thread_info_flags)
{
	local_irq_enable();

	user_exit();

	/* deal with pending signal delivery */
	if (thread_info_flags & _TIF_SIGPENDING)
		do_signal(regs);

	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
		clear_thread_flag(TIF_NOTIFY_RESUME);
		tracehook_notify_resume(regs);
	}

	user_enter();
}

void default_idle(void)
{
	if (hlt_works()) {
		clear_thread_flag(TIF_POLLING_NRFLAG);
		smp_mb__after_clear_bit();

		set_bl_bit();
		if (!need_resched()) {
			local_irq_enable();
			cpu_sleep();
		} else
			local_irq_enable();

		set_thread_flag(TIF_POLLING_NRFLAG);
		clear_bl_bit();
	} else
		poll_idle();
}

static void default_idle(void)
{
	if (!hlt_counter) {
		clear_thread_flag(TIF_POLLING_NRFLAG);
		smp_mb__after_clear_bit();
		set_bl_bit();
		stop_critical_timings();

		while (!need_resched())
			cpu_sleep();

		start_critical_timings();
		clear_bl_bit();
		set_thread_flag(TIF_POLLING_NRFLAG);
	} else
		while (!need_resched())
			cpu_relax();
}

/*
 * cpu_init() initializes state that is per-CPU.
 */
void __cpuinit cpu_init(void)
{
        /*
         * Store processor id in lowcore (used e.g. in timer_interrupt)
         */
	get_cpu_id(&S390_lowcore.cpu_id);

        /*
         * Force FPU initialization:
         */
        clear_thread_flag(TIF_USEDFPU);
        clear_used_math();

	atomic_inc(&init_mm.mm_count);
	current->active_mm = &init_mm;
	BUG_ON(current->mm);
        enter_lazy_tlb(&init_mm, current);
}

/*
 * Called immediately after a successful exec.
 */
void arch_setup_new_exec(void)
{
	/* If cpuid was previously disabled for this task, re-enable it. */
	if (test_thread_flag(TIF_NOCPUID))
		enable_cpuid();

	/*
	 * Don't inherit TIF_SSBD across exec boundary when
	 * PR_SPEC_DISABLE_NOEXEC is used.
	 */
	if (test_thread_flag(TIF_SSBD) &&
	    task_spec_ssb_noexec(current)) {
		clear_thread_flag(TIF_SSBD);
		task_clear_spec_ssb_disable(current);
		task_clear_spec_ssb_noexec(current);
		speculation_ctrl_update(task_thread_info(current)->flags);
	}
}

void default_idle(void)
{
	if (likely(hlt_counter)) {
		local_irq_disable();
		stop_critical_timings();
		cpu_relax();
		start_critical_timings();
		local_irq_enable();
	} else {
		clear_thread_flag(TIF_POLLING_NRFLAG);
		smp_mb__after_clear_bit();
		local_irq_disable();
		while (!need_resched())
			cpu_sleep();
		local_irq_enable();
		set_thread_flag(TIF_POLLING_NRFLAG);
	}
}

static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
{
	/*
	 * In order to return to user mode, we need to have IRQs off with
	 * none of EXIT_TO_USERMODE_LOOP_FLAGS set.  Several of these flags
	 * can be set at any time on preemptible kernels if we have IRQs on,
	 * so we need to loop.  Disabling preemption wouldn't help: doing the
	 * work to clear some of the flags can sleep.
	 */
	while (true) {
		/* We have work to do. */
		local_irq_enable();

		if (cached_flags & _TIF_NEED_RESCHED)
			schedule();

		if (cached_flags & _TIF_UPROBE)
			uprobe_notify_resume(regs);

		if (cached_flags & _TIF_PATCH_PENDING)
			klp_update_patch_state(current);

		/* deal with pending signal delivery */
		if (cached_flags & _TIF_SIGPENDING)
			do_signal(regs);

		if (cached_flags & _TIF_NOTIFY_RESUME) {
			clear_thread_flag(TIF_NOTIFY_RESUME);
			tracehook_notify_resume(regs);
			rseq_handle_notify_resume(NULL, regs);
		}

		if (cached_flags & _TIF_USER_RETURN_NOTIFY)
			fire_user_return_notifiers();

		/* Disable IRQs and retry */
		local_irq_disable();

		cached_flags = READ_ONCE(current_thread_info()->flags);

		if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
			break;
	}
}

static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
		unsigned long timeout, wait_queue_head_t *queue,
		bool check_cancel)
{
	unsigned long stop;
	long rc;
	u8 status;
	bool canceled = false;

	/* check current status */
	status = chip->ops->status(chip);
	if ((status & mask) == mask)
		return 0;

	stop = jiffies + timeout;

	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
again:
		timeout = stop - jiffies;
		if ((long)timeout <= 0)
			return -ETIME;
		rc = wait_event_interruptible_timeout(*queue,
			wait_for_tpm_stat_cond(chip, mask, check_cancel,
					       &canceled),
			timeout);
		if (rc > 0) {
			if (canceled)
				return -ECANCELED;
			return 0;
		}
		if (rc == -ERESTARTSYS && freezing(current)) {
			clear_thread_flag(TIF_SIGPENDING);
			goto again;
		}
	} else {
		do {
			tpm_msleep(TPM_TIMEOUT);
			status = chip->ops->status(chip);
			if ((status & mask) == mask)
				return 0;
		} while (time_before(jiffies, stop));
	}
	return -ETIME;
}

static int snooze_loop(struct cpuidle_device *dev,
			struct cpuidle_driver *drv,
			int index)
{
	local_irq_enable();
	set_thread_flag(TIF_POLLING_NRFLAG);

	ppc64_runlatch_off();
	while (!need_resched()) {
		HMT_low();
		HMT_very_low();
	}

	HMT_medium();
	ppc64_runlatch_on();
	clear_thread_flag(TIF_POLLING_NRFLAG);
	smp_mb();
	return index;
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
	struct task_struct *me = current;
	struct thread_struct *t = &me->thread;
	unsigned long *bp = t->io_bitmap_ptr;

	if (bp) {
		struct tss_struct *tss = init_tss + get_cpu();

		t->io_bitmap_ptr = NULL;
		clear_thread_flag(TIF_IO_BITMAP);
		/*
		 * Careful, clear this in the TSS too:
		 */
		memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
		t->io_bitmap_max = 0;
		put_cpu();
		kfree(bp);
	}
}