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[06/11] dma: xilinx: vdma: Check if the segment list is empty in a descriptor

Message ID 1412022477-28749-7-git-send-email-laurent.pinchart@ideasonboard.com (mailing list archive)
State Superseded
Headers show

Commit Message

Laurent Pinchart Sept. 29, 2014, 8:27 p.m. UTC 
From: Srikanth Thokala <srikanth.thokala@xilinx.com>

The segment list in a descriptor should be checked for empty, else
it will try to access invalid address for the first call.  This
patch fixes this issue.

Signed-off-by: Srikanth Thokala <sthokal@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---
 drivers/dma/xilinx/xilinx_vdma.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Cc: dmaengine@vger.kernel.org
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Patch

diff --git a/drivers/dma/xilinx/xilinx_vdma.c b/drivers/dma/xilinx/xilinx_vdma.c
index 42a13e8..8e9f2a6 100644
--- a/drivers/dma/xilinx/xilinx_vdma.c
+++ b/drivers/dma/xilinx/xilinx_vdma.c
@@ -971,9 +971,11 @@  xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
 		hw->buf_addr = xt->src_start;
 
 	/* Link the previous next descriptor to current */
-	prev = list_last_entry(&desc->segments,
-				struct xilinx_vdma_tx_segment, node);
-	prev->hw.next_desc = segment->phys;
+	if (!list_empty(&desc->segments)) {
+		prev = list_last_entry(&desc->segments,
+				       struct xilinx_vdma_tx_segment, node);
+		prev->hw.next_desc = segment->phys;
+	}
 
 	/* Insert the segment into the descriptor segments list. */
 	list_add_tail(&segment->node, &desc->segments);