dmaengine: xilinx: vdma: Check if the segment list is empty in a descriptor

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>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/xilinx/xilinx_vdma.c b/drivers/dma/xilinx/xilinx_vdma.c
index a6e6476..1093794 100644 (file)
--- 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);