From 40db8f468fe0895daf042f3f718c6034d02b5ca6 Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Sun, 9 Feb 2020 19:33:39 +0300 Subject: [PATCH] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list 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 Acked-by: Jon Hunter Cc: Link: https://lore.kernel.org/r/20200209163356.6439-3-digetx@gmail.com Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- 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 84d4d9e..4eaf92b 100644 --- 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_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; -- 2.7.4