[PATCH 4/4] dmaengine: xilinx_dma: Add device synchronisation callback
From: Adrian Larumbe <hidden>
Date: 2021-04-23 01:22:00
Also in:
dmaengine
Subsystem:
dma generic offload engine subsystem, the rest · Maintainers:
Vinod Koul, Linus Torvalds
This was required as an answer to a very unusual race condition, whereby a thread waiting on a completion signaled in a callback triggered by dmaengine_desc_callback_invoke might immediately attempt to release the DMA channel whilst the channel lock was still free. This would cause the remaining descriptors to be deallocated, and xilinx_dma_chan_desc_cleanup to perform an invalid memory access when attempting to traverse the rest of the channel's done_list. Now, when releasing a DMA channel, it will wait until the tasklet has finished. Signed-off-by: Adrian Larumbe <redacted> --- drivers/dma/xilinx/xilinx_dma.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 40c6cf8bf0e6..d4bad999e7f9 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c@@ -942,6 +942,13 @@ static void xilinx_dma_free_chan_resources(struct dma_chan *dchan) } +static void xilinx_dma_synchronize(struct dma_chan *dchan) +{ + struct xilinx_dma_chan *chan = to_xilinx_chan(dchan); + + tasklet_kill(&chan->tasklet); +} + /** * xilinx_dma_get_residue - Compute residue for a given descriptor * @chan: Driver specific dma channel
@@ -3235,6 +3242,7 @@ static int xilinx_dma_probe(struct platform_device *pdev) xdev->common.device_tx_status = xilinx_dma_tx_status; xdev->common.device_issue_pending = xilinx_dma_issue_pending; xdev->common.device_config = xilinx_dma_slave_config; + xdev->common.device_synchronize = xilinx_dma_synchronize; if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) { dma_cap_set(DMA_CYCLIC, xdev->common.cap_mask); xdev->common.device_prep_slave_sg = xilinx_dma_prep_slave_sg;
--
2.17.1
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