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: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index c850dfdfa9e32712136ed7515f1440dbe7906805..ad87a98f8f68f48f4191bac3f2202c45eb26dadf 100644 (file)
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -472,25 +472,52 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
        dma_cookie_t cookie;
        int ret;
 
-       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;
-       }
+       /* 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)
-                       goto no_dma;
+               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) {
+                       ret = -EAGAIN;
+                       goto no_dma_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)) {
+                       ret = cookie;
+                       goto no_dma_tx;
+               }
+
+               irq_mask |= SPCR_SPTIE;
+       }
+
        /*
         * DMAC needs SPxIE, but if SPxIE is set, the IRQ routine will be
         * called. So, this driver disables the IRQ while DMA transfer.
@@ -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:
-       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;
+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 ret;
 }
 
 static void rspi_receive_init(const struct rspi_data *rspi)