[SCSI] QLOGICPTI: Do not unmap DMA unless we actually mapped something.
We only map DMA when cmd->request_bufflen is non-zero for non-sg
buffers, we thus should make the same check when unmapping.
Based upon a report from Pasi Pirhonen.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/scsi/qlogicpti.c b/drivers/scsi/qlogicpti.c
index 9b827ce..9f10689 100644
--- a/drivers/scsi/qlogicpti.c
+++ b/drivers/scsi/qlogicpti.c
@@ -1281,7 +1281,7 @@
(struct scatterlist *)Cmnd->request_buffer,
Cmnd->use_sg,
Cmnd->sc_data_direction);
- } else {
+ } else if (Cmnd->request_bufflen) {
sbus_unmap_single(qpti->sdev,
(__u32)((unsigned long)Cmnd->SCp.ptr),
Cmnd->request_bufflen,