static int rpm_suspend()

in power/runtime.c [553:737]

• 123 lines of code
• 30 McCabe index (conditional complexity)

static int rpm_suspend(struct device *dev, int rpmflags)
	__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
	int (*callback)(struct device *);
	struct device *parent = NULL;
	int retval;

	trace_rpm_suspend_rcuidle(dev, rpmflags);

 repeat:
	retval = rpm_check_suspend_allowed(dev);
	if (retval < 0)
		goto out;	/* Conditions are wrong. */

	/* Synchronous suspends are not allowed in the RPM_RESUMING state. */
	if (dev->power.runtime_status == RPM_RESUMING && !(rpmflags & RPM_ASYNC))
		retval = -EAGAIN;
	if (retval)
		goto out;

	/* If the autosuspend_delay time hasn't expired yet, reschedule. */
	if ((rpmflags & RPM_AUTO)
	    && dev->power.runtime_status != RPM_SUSPENDING) {
		u64 expires = pm_runtime_autosuspend_expiration(dev);

		if (expires != 0) {
			/* Pending requests need to be canceled. */
			dev->power.request = RPM_REQ_NONE;

			/*
			 * Optimization: If the timer is already running and is
			 * set to expire at or before the autosuspend delay,
			 * avoid the overhead of resetting it.  Just let it
			 * expire; pm_suspend_timer_fn() will take care of the
			 * rest.
			 */
			if (!(dev->power.timer_expires &&
					dev->power.timer_expires <= expires)) {
				/*
				 * We add a slack of 25% to gather wakeups
				 * without sacrificing the granularity.
				 */
				u64 slack = (u64)READ_ONCE(dev->power.autosuspend_delay) *
						    (NSEC_PER_MSEC >> 2);

				dev->power.timer_expires = expires;
				hrtimer_start_range_ns(&dev->power.suspend_timer,
						ns_to_ktime(expires),
						slack,
						HRTIMER_MODE_ABS);
			}
			dev->power.timer_autosuspends = 1;
			goto out;
		}
	}

	/* Other scheduled or pending requests need to be canceled. */
	pm_runtime_cancel_pending(dev);

	if (dev->power.runtime_status == RPM_SUSPENDING) {
		DEFINE_WAIT(wait);

		if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
			retval = -EINPROGRESS;
			goto out;
		}

		if (dev->power.irq_safe) {
			spin_unlock(&dev->power.lock);

			cpu_relax();

			spin_lock(&dev->power.lock);
			goto repeat;
		}

		/* Wait for the other suspend running in parallel with us. */
		for (;;) {
			prepare_to_wait(&dev->power.wait_queue, &wait,
					TASK_UNINTERRUPTIBLE);
			if (dev->power.runtime_status != RPM_SUSPENDING)
				break;

			spin_unlock_irq(&dev->power.lock);

			schedule();

			spin_lock_irq(&dev->power.lock);
		}
		finish_wait(&dev->power.wait_queue, &wait);
		goto repeat;
	}

	if (dev->power.no_callbacks)
		goto no_callback;	/* Assume success. */

	/* Carry out an asynchronous or a synchronous suspend. */
	if (rpmflags & RPM_ASYNC) {
		dev->power.request = (rpmflags & RPM_AUTO) ?
		    RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
		if (!dev->power.request_pending) {
			dev->power.request_pending = true;
			queue_work(pm_wq, &dev->power.work);
		}
		goto out;
	}

	__update_runtime_status(dev, RPM_SUSPENDING);

	callback = RPM_GET_CALLBACK(dev, runtime_suspend);

	dev_pm_enable_wake_irq_check(dev, true);
	retval = rpm_callback(callback, dev);
	if (retval)
		goto fail;

	dev_pm_enable_wake_irq_complete(dev);

 no_callback:
	__update_runtime_status(dev, RPM_SUSPENDED);
	pm_runtime_deactivate_timer(dev);

	if (dev->parent) {
		parent = dev->parent;
		atomic_add_unless(&parent->power.child_count, -1, 0);
	}
	wake_up_all(&dev->power.wait_queue);

	if (dev->power.deferred_resume) {
		dev->power.deferred_resume = false;
		rpm_resume(dev, 0);
		retval = -EAGAIN;
		goto out;
	}

	if (dev->power.irq_safe)
		goto out;

	/* Maybe the parent is now able to suspend. */
	if (parent && !parent->power.ignore_children) {
		spin_unlock(&dev->power.lock);

		spin_lock(&parent->power.lock);
		rpm_idle(parent, RPM_ASYNC);
		spin_unlock(&parent->power.lock);

		spin_lock(&dev->power.lock);
	}
	/* Maybe the suppliers are now able to suspend. */
	if (dev->power.links_count > 0) {
		spin_unlock_irq(&dev->power.lock);

		rpm_suspend_suppliers(dev);

		spin_lock_irq(&dev->power.lock);
	}

 out:
	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);

	return retval;

 fail:
	dev_pm_disable_wake_irq_check(dev, true);
	__update_runtime_status(dev, RPM_ACTIVE);
	dev->power.deferred_resume = false;
	wake_up_all(&dev->power.wait_queue);

	if (retval == -EAGAIN || retval == -EBUSY) {
		dev->power.runtime_error = 0;

		/*
		 * If the callback routine failed an autosuspend, and
		 * if the last_busy time has been updated so that there
		 * is a new autosuspend expiration time, automatically
		 * reschedule another autosuspend.
		 */
		if ((rpmflags & RPM_AUTO) &&
		    pm_runtime_autosuspend_expiration(dev) != 0)
			goto repeat;
	} else {
		pm_runtime_cancel_pending(dev);
	}
	goto out;
}