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dmaengine: xilinx_dma: Add missing check for empty list 

The DMA transfer might finish just after checking the state with
dma_cookie_status, but before the lock is acquired. Not checking
for an empty list in xilinx_dma_tx_status may result in reading
random data or data corruption when desc is written to. This can
be reliably triggered by using dma_sync_wait to wait for DMA
completion.

Signed-off-by: Sebastian von Ohr <vonohr@smaract.com>
Tested-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/20200303130518.333-1-vonohr@smaract.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Sebastian von Ohr 2020-03-03 14:05:18 +01:00 committed by Vinod Koul
parent 172d59ecd6
commit b269426011
1 changed files with 10 additions and 10 deletions
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20
drivers/dma/xilinx/xilinx_dma.c
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@ -1230,16 +1230,16 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
return ret;
spin_lock_irqsave(&chan->lock, flags);
desc = list_last_entry(&chan->active_list,
struct xilinx_dma_tx_descriptor, node);
/*
* VDMA and simple mode do not support residue reporting, so the
* residue field will always be 0.
*/
if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
residue = xilinx_dma_get_residue(chan, desc);
if (!list_empty(&chan->active_list)) {
desc = list_last_entry(&chan->active_list,
struct xilinx_dma_tx_descriptor, node);
/*
* VDMA and simple mode do not support residue reporting, so the
* residue field will always be 0.
*/
if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
residue = xilinx_dma_get_residue(chan, desc);
}
spin_unlock_irqrestore(&chan->lock, flags);
dma_set_residue(txstate, residue);