static int rpm_resume()

in power/runtime.c [756:931]

• 125 lines of code
• 37 McCabe index (conditional complexity)

static int rpm_resume(struct device *dev, int rpmflags)
	__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
	int (*callback)(struct device *);
	struct device *parent = NULL;
	int retval = 0;

	trace_rpm_resume_rcuidle(dev, rpmflags);

 repeat:
	if (dev->power.runtime_error) {
		retval = -EINVAL;
	} else if (dev->power.disable_depth > 0) {
		if (dev->power.runtime_status == RPM_ACTIVE &&
		    dev->power.last_status == RPM_ACTIVE)
			retval = 1;
		else
			retval = -EACCES;
	}
	if (retval)
		goto out;

	/*
	 * Other scheduled or pending requests need to be canceled.  Small
	 * optimization: If an autosuspend timer is running, leave it running
	 * rather than cancelling it now only to restart it again in the near
	 * future.
	 */
	dev->power.request = RPM_REQ_NONE;
	if (!dev->power.timer_autosuspends)
		pm_runtime_deactivate_timer(dev);

	if (dev->power.runtime_status == RPM_ACTIVE) {
		retval = 1;
		goto out;
	}

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

		if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
			if (dev->power.runtime_status == RPM_SUSPENDING)
				dev->power.deferred_resume = true;
			else
				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 operation carried out in parallel with us. */
		for (;;) {
			prepare_to_wait(&dev->power.wait_queue, &wait,
					TASK_UNINTERRUPTIBLE);
			if (dev->power.runtime_status != RPM_RESUMING
			    && 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;
	}

	/*
	 * See if we can skip waking up the parent.  This is safe only if
	 * power.no_callbacks is set, because otherwise we don't know whether
	 * the resume will actually succeed.
	 */
	if (dev->power.no_callbacks && !parent && dev->parent) {
		spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
		if (dev->parent->power.disable_depth > 0
		    || dev->parent->power.ignore_children
		    || dev->parent->power.runtime_status == RPM_ACTIVE) {
			atomic_inc(&dev->parent->power.child_count);
			spin_unlock(&dev->parent->power.lock);
			retval = 1;
			goto no_callback;	/* Assume success. */
		}
		spin_unlock(&dev->parent->power.lock);
	}

	/* Carry out an asynchronous or a synchronous resume. */
	if (rpmflags & RPM_ASYNC) {
		dev->power.request = RPM_REQ_RESUME;
		if (!dev->power.request_pending) {
			dev->power.request_pending = true;
			queue_work(pm_wq, &dev->power.work);
		}
		retval = 0;
		goto out;
	}

	if (!parent && dev->parent) {
		/*
		 * Increment the parent's usage counter and resume it if
		 * necessary.  Not needed if dev is irq-safe; then the
		 * parent is permanently resumed.
		 */
		parent = dev->parent;
		if (dev->power.irq_safe)
			goto skip_parent;
		spin_unlock(&dev->power.lock);

		pm_runtime_get_noresume(parent);

		spin_lock(&parent->power.lock);
		/*
		 * Resume the parent if it has runtime PM enabled and not been
		 * set to ignore its children.
		 */
		if (!parent->power.disable_depth
		    && !parent->power.ignore_children) {
			rpm_resume(parent, 0);
			if (parent->power.runtime_status != RPM_ACTIVE)
				retval = -EBUSY;
		}
		spin_unlock(&parent->power.lock);

		spin_lock(&dev->power.lock);
		if (retval)
			goto out;
		goto repeat;
	}
 skip_parent:

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

	__update_runtime_status(dev, RPM_RESUMING);

	callback = RPM_GET_CALLBACK(dev, runtime_resume);

	dev_pm_disable_wake_irq_check(dev, false);
	retval = rpm_callback(callback, dev);
	if (retval) {
		__update_runtime_status(dev, RPM_SUSPENDED);
		pm_runtime_cancel_pending(dev);
		dev_pm_enable_wake_irq_check(dev, false);
	} else {
 no_callback:
		__update_runtime_status(dev, RPM_ACTIVE);
		pm_runtime_mark_last_busy(dev);
		if (parent)
			atomic_inc(&parent->power.child_count);
	}
	wake_up_all(&dev->power.wait_queue);

	if (retval >= 0)
		rpm_idle(dev, RPM_ASYNC);

 out:
	if (parent && !dev->power.irq_safe) {
		spin_unlock_irq(&dev->power.lock);

		pm_runtime_put(parent);

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

	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);

	return retval;
}