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dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list 

commit c33ee1301c 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>
This commit is contained in:
Dmitry Osipenko 2020-02-09 19:33:39 +03:00 committed by Greg Kroah-Hartman
parent 454ee4a820
commit ac5e2d2d5f
1 changed files with 1 additions and 1 deletions
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2
drivers/dma/tegra20-apb-dma.c
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@ -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;