Commit 3819bc87 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Mark Brown
Browse files

spi: rspi: Fix leaking of unused DMA descriptors 



If dmaengine_prep_slave_sg() or dmaengine_submit() fail, we may leak
unused DMA descriptors.

As per Documentation/dmaengine.txt, once a DMA descriptor has been
obtained, it must be submitted. Hence:
  - First prepare and submit all DMA descriptors,
  - Prepare the SPI controller for DMA,
  - Start DMA by calling dma_async_issue_pending(),
  - Make sure to call dmaengine_terminate_all() on all descriptors that
    haven't completed.

Reported-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarMark Brown <broonie@linaro.org>
parent 7d1311b9

drivers/spi/spi-rspi.c

+58 −36
Original line number Diff line number Diff line
@@ -472,23 +472,50 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx, 
	dma_cookie_t cookie;

	int ret;



	/* First prepare and submit the DMA request(s), as this may fail */

	if (rx) {

		desc_rx = dmaengine_prep_slave_sg(rspi->master->dma_rx,

					rx->sgl, rx->nents, DMA_FROM_DEVICE,

					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

		if (!desc_rx) {

			ret = -EAGAIN;

			goto no_dma_rx;

		}



		desc_rx->callback = rspi_dma_complete;

		desc_rx->callback_param = rspi;

		cookie = dmaengine_submit(desc_rx);

		if (dma_submit_error(cookie)) {

			ret = cookie;

			goto no_dma_rx;

		}



		irq_mask |= SPCR_SPRIE;

	}



	if (tx) {

		desc_tx = dmaengine_prep_slave_sg(rspi->master->dma_tx,

					tx->sgl, tx->nents, DMA_TO_DEVICE,

					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

		if (!desc_tx)

			goto no_dma;



		irq_mask |= SPCR_SPTIE;

		if (!desc_tx) {

			ret = -EAGAIN;

			goto no_dma_tx;

		}



		if (rx) {

		desc_rx = dmaengine_prep_slave_sg(rspi->master->dma_rx,

					rx->sgl, rx->nents, DMA_FROM_DEVICE,

					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);

		if (!desc_rx)

			goto no_dma;

			/* No callback */

			desc_tx->callback = NULL;

		} else {

			desc_tx->callback = rspi_dma_complete;

			desc_tx->callback_param = rspi;

		}

		cookie = dmaengine_submit(desc_tx);

		if (dma_submit_error(cookie)) {

			ret = cookie;

			goto no_dma_tx;

		}



		irq_mask |= SPCR_SPRIE;

		irq_mask |= SPCR_SPTIE;

	}



	/*
@@ -503,34 +530,24 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx, 
	rspi_enable_irq(rspi, irq_mask);

	rspi->dma_callbacked = 0;



	if (rx) {

		desc_rx->callback = rspi_dma_complete;

		desc_rx->callback_param = rspi;

		cookie = dmaengine_submit(desc_rx);

		if (dma_submit_error(cookie))

			return cookie;

	/* Now start DMA */

	if (rx)

		dma_async_issue_pending(rspi->master->dma_rx);

	}

	if (tx) {

		if (rx) {

			/* No callback */

			desc_tx->callback = NULL;

		} else {

			desc_tx->callback = rspi_dma_complete;

			desc_tx->callback_param = rspi;

		}

		cookie = dmaengine_submit(desc_tx);

		if (dma_submit_error(cookie))

			return cookie;

	if (tx)

		dma_async_issue_pending(rspi->master->dma_tx);

	}



	ret = wait_event_interruptible_timeout(rspi->wait,

					       rspi->dma_callbacked, HZ);

	if (ret > 0 && rspi->dma_callbacked)

		ret = 0;

	else if (!ret)

	else if (!ret) {

		dev_err(&rspi->master->dev, "DMA timeout\n");

		ret = -ETIMEDOUT;

		if (tx)

			dmaengine_terminate_all(rspi->master->dma_tx);

		if (rx)

			dmaengine_terminate_all(rspi->master->dma_rx);

	}



	rspi_disable_irq(rspi, irq_mask);
@@ -541,11 +558,16 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx, 


	return ret;



no_dma:

no_dma_tx:

	if (rx)

		dmaengine_terminate_all(rspi->master->dma_rx);

no_dma_rx:

	if (ret == -EAGAIN) {

		pr_warn_once("%s %s: DMA not available, falling back to PIO\n",

			     dev_driver_string(&rspi->master->dev),

			     dev_name(&rspi->master->dev));

	return -EAGAIN;

	}

	return ret;

}



static void rspi_receive_init(const struct rspi_data *rspi)

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