static void __spi_pump_messages()

in spi.c [1548:1701]

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

static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
{
	struct spi_transfer *xfer;
	struct spi_message *msg;
	bool was_busy = false;
	unsigned long flags;
	int ret;

	/* Lock queue */
	spin_lock_irqsave(&ctlr->queue_lock, flags);

	/* Make sure we are not already running a message */
	if (ctlr->cur_msg) {
		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
		return;
	}

	/* If another context is idling the device then defer */
	if (ctlr->idling) {
		kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
		return;
	}

	/* Check if the queue is idle */
	if (list_empty(&ctlr->queue) || !ctlr->running) {
		if (!ctlr->busy) {
			spin_unlock_irqrestore(&ctlr->queue_lock, flags);
			return;
		}

		/* Defer any non-atomic teardown to the thread */
		if (!in_kthread) {
			if (!ctlr->dummy_rx && !ctlr->dummy_tx &&
			    !ctlr->unprepare_transfer_hardware) {
				spi_idle_runtime_pm(ctlr);
				ctlr->busy = false;
				trace_spi_controller_idle(ctlr);
			} else {
				kthread_queue_work(ctlr->kworker,
						   &ctlr->pump_messages);
			}
			spin_unlock_irqrestore(&ctlr->queue_lock, flags);
			return;
		}

		ctlr->busy = false;
		ctlr->idling = true;
		spin_unlock_irqrestore(&ctlr->queue_lock, flags);

		kfree(ctlr->dummy_rx);
		ctlr->dummy_rx = NULL;
		kfree(ctlr->dummy_tx);
		ctlr->dummy_tx = NULL;
		if (ctlr->unprepare_transfer_hardware &&
		    ctlr->unprepare_transfer_hardware(ctlr))
			dev_err(&ctlr->dev,
				"failed to unprepare transfer hardware\n");
		spi_idle_runtime_pm(ctlr);
		trace_spi_controller_idle(ctlr);

		spin_lock_irqsave(&ctlr->queue_lock, flags);
		ctlr->idling = false;
		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
		return;
	}

	/* Extract head of queue */
	msg = list_first_entry(&ctlr->queue, struct spi_message, queue);
	ctlr->cur_msg = msg;

	list_del_init(&msg->queue);
	if (ctlr->busy)
		was_busy = true;
	else
		ctlr->busy = true;
	spin_unlock_irqrestore(&ctlr->queue_lock, flags);

	mutex_lock(&ctlr->io_mutex);

	if (!was_busy && ctlr->auto_runtime_pm) {
		ret = pm_runtime_get_sync(ctlr->dev.parent);
		if (ret < 0) {
			pm_runtime_put_noidle(ctlr->dev.parent);
			dev_err(&ctlr->dev, "Failed to power device: %d\n",
				ret);
			mutex_unlock(&ctlr->io_mutex);
			return;
		}
	}

	if (!was_busy)
		trace_spi_controller_busy(ctlr);

	if (!was_busy && ctlr->prepare_transfer_hardware) {
		ret = ctlr->prepare_transfer_hardware(ctlr);
		if (ret) {
			dev_err(&ctlr->dev,
				"failed to prepare transfer hardware: %d\n",
				ret);

			if (ctlr->auto_runtime_pm)
				pm_runtime_put(ctlr->dev.parent);

			msg->status = ret;
			spi_finalize_current_message(ctlr);

			mutex_unlock(&ctlr->io_mutex);
			return;
		}
	}

	trace_spi_message_start(msg);

	if (ctlr->prepare_message) {
		ret = ctlr->prepare_message(ctlr, msg);
		if (ret) {
			dev_err(&ctlr->dev, "failed to prepare message: %d\n",
				ret);
			msg->status = ret;
			spi_finalize_current_message(ctlr);
			goto out;
		}
		ctlr->cur_msg_prepared = true;
	}

	ret = spi_map_msg(ctlr, msg);
	if (ret) {
		msg->status = ret;
		spi_finalize_current_message(ctlr);
		goto out;
	}

	if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
			xfer->ptp_sts_word_pre = 0;
			ptp_read_system_prets(xfer->ptp_sts);
		}
	}

	ret = ctlr->transfer_one_message(ctlr, msg);
	if (ret) {
		dev_err(&ctlr->dev,
			"failed to transfer one message from queue\n");
		goto out;
	}

out:
	mutex_unlock(&ctlr->io_mutex);

	/* Prod the scheduler in case transfer_one() was busy waiting */
	if (!ret)
		cond_resched();
}