[v4,05/14] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list
diff mbox series

Message ID 20200112173006.29863-6-digetx@gmail.com
State Changes Requested
Headers show
Series
  • NVIDIA Tegra APB DMA driver fixes and improvements
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Commit Message

Dmitry Osipenko Jan. 12, 2020, 5:29 p.m. UTC
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>
---
 drivers/dma/tegra20-apb-dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Jon Hunter Jan. 14, 2020, 3:43 p.m. UTC | #1
On 12/01/2020 17:29, Dmitry Osipenko wrote:
> 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>
> ---
>  drivers/dma/tegra20-apb-dma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index 1b8a11804962..aafad50d075e 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -281,7 +281,7 @@ static struct tegra_dma_desc *tegra_dma_desc_get(
>  
>  	/* 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;
> 

Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

Patch
diff mbox series

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 1b8a11804962..aafad50d075e 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -281,7 +281,7 @@  static struct tegra_dma_desc *tegra_dma_desc_get(
 
 	/* 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;