[PATCH 1/7] dmaengine: edma: fix two faults which happen with the 8250_dma user

Sebastian Andrzej Siewior
2014-07-29T19:00:26Z

The rx path of the 8250_dma user in the RX-timeout case:
- it starts the RX transfer
- if the rx-timeout interrupt occures, it dmaengine_pause() the transfer
- step two is dmaengine_terminate_all() on this channel.
- based on dmaengine_tx_status() it learns the number of transfered
bytes.
- the rx interrupt occures, it does not start the RX-transfer because
according to dmaengine_tx_status() the status of the current transfer
is still DMA_IN_PROGRESS because the earlier dmaengine_terminate_all()
did not reset this.
- on rx-timeout it invokes dmaengine_pause() again. This time, it
segfaults because the channel has no descriptor yet.

To make the upper case work better, this patch adds dma_cookie_complete()
to complete the cookie. Also it adds is an additional check for echan->edesc
in case the channel has no descriptor assigned.

Cc: Joel Fernandes <joelf@ti.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: dmaengine@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/dma/edma.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index d08c4de..ff05dd4 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -256,6 +256,7 @@ static int edma_terminate_all(struct edma_chan *echan)
* echan->edesc is NULL and exit.)
*/
if (echan->edesc) {
+ dma_cookie_complete(&echan->edesc->vdesc.tx);
echan->edesc = NULL;
edma_stop(echan->ch_num);
}
@@ -282,7 +283,7 @@ static int edma_slave_config(struct edma_chan *echan,
static int edma_dma_pause(struct edma_chan *echan)
{
/* Pause/Resume only allowed with cyclic mode */
- if (!echan->edesc->cyclic)
+ if (!echan->edesc || !echan->edesc->cyclic)
return -EINVAL;

edma_pause(echan->ch_num);
--
2.0.1