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Subject[PATCH] dmaengine: edma: Fetch echan->edesc while holding lock in edma_comletion_handler
Date
In order to avoid possible race condition when client drivers are using
dmaengine_terminate_sync() call to disable the channel.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Suggested-by: Lars-Peter Clausen <lars@metafoo.de>
---
drivers/dma/edma.c | 54 +++++++++++++++++++++++++++---------------------------
1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 290e1a721c5b..13b6a23dc06b 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -1372,36 +1372,36 @@ static struct dma_async_tx_descriptor *edma_prep_dma_cyclic(
static void edma_completion_handler(struct edma_chan *echan)
{
struct device *dev = echan->vchan.chan.device->dev;
- struct edma_desc *edesc = echan->edesc;
-
- if (!edesc)
- return;
+ struct edma_desc *edesc;

spin_lock(&echan->vchan.lock);
- if (edesc->cyclic) {
- vchan_cyclic_callback(&edesc->vdesc);
- spin_unlock(&echan->vchan.lock);
- return;
- } else if (edesc->processed == edesc->pset_nr) {
- edesc->residue = 0;
- edma_stop(echan);
- vchan_cookie_complete(&edesc->vdesc);
- echan->edesc = NULL;
-
- dev_dbg(dev, "Transfer completed on channel %d\n",
- echan->ch_num);
- } else {
- dev_dbg(dev, "Sub transfer completed on channel %d\n",
- echan->ch_num);
-
- edma_pause(echan);
-
- /* Update statistics for tx_status */
- edesc->residue -= edesc->sg_len;
- edesc->residue_stat = edesc->residue;
- edesc->processed_stat = edesc->processed;
+ edesc = echan->edesc;
+ if (edesc) {
+ if (edesc->cyclic) {
+ vchan_cyclic_callback(&edesc->vdesc);
+ spin_unlock(&echan->vchan.lock);
+ return;
+ } else if (edesc->processed == edesc->pset_nr) {
+ edesc->residue = 0;
+ edma_stop(echan);
+ vchan_cookie_complete(&edesc->vdesc);
+ echan->edesc = NULL;
+
+ dev_dbg(dev, "Transfer completed on channel %d\n",
+ echan->ch_num);
+ } else {
+ dev_dbg(dev, "Sub transfer completed on channel %d\n",
+ echan->ch_num);
+
+ edma_pause(echan);
+
+ /* Update statistics for tx_status */
+ edesc->residue -= edesc->sg_len;
+ edesc->residue_stat = edesc->residue;
+ edesc->processed_stat = edesc->processed;
+ }
+ edma_execute(echan);
}
- edma_execute(echan);

spin_unlock(&echan->vchan.lock);
}
--
2.7.1
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