diff mbox series

[4.19,54/86] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list

Message ID 20200310124533.710299227@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg KH March 10, 2020, 12:45 p.m. UTC 
From: Dmitry Osipenko <digetx@gmail.com>

commit c33ee1301c393a241d6424e36eff1071811b1064 upstream.

The interrupt handler puts a half-completed DMA descriptor on a free list
and then schedules tasklet to process bottom half of the descriptor that
executes client's callback, this creates possibility to pick up the busy
descriptor from the free list. Thus, let's disallow descriptor's re-use
until it is fully processed.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200209163356.6439-3-digetx@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/tegra20-apb-dma.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -288,7 +288,7 @@  static struct tegra_dma_desc *tegra_dma_
 
 	/* Do not allocate if desc are waiting for ack */
 	list_for_each_entry(dma_desc, &tdc->free_dma_desc, node) {
-		if (async_tx_test_ack(&dma_desc->txd)) {
+		if (async_tx_test_ack(&dma_desc->txd) && !dma_desc->cb_count) {
 			list_del(&dma_desc->node);
 			spin_unlock_irqrestore(&tdc->lock, flags);
 			dma_desc->txd.flags = 0;