scsi: dc395x: fix DMA API usage in sg_update_list

BugLink: https://bugs.launchpad.net/bugs/1854855

[ Upstream commit 6c404a68 ]

We need to transfer device ownership to the CPU before we can manipulate
the mapped data.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/scsi/dc395x.c

@@ -1972,6 +1972,11 @@ static void sg_update_list(struct ScsiReqBlk *srb, u32 left)
 			xferred -= psge->length;
 		} else {
 			/* Partial SG entry done */
+			pci_dma_sync_single_for_cpu(srb->dcb->
+					    acb->dev,
+					    srb->sg_bus_addr,
+					    SEGMENTX_LEN,
+					    PCI_DMA_TODEVICE);
 			psge->length -= xferred;
 			psge->address += xferred;
 			srb->sg_index = idx;