BUG_ON on kernel misbehavior on A100U2W driver

With broken Sparc64 IOMMU accounting, the kernel submits larger requests
then allowed.  Better to crash on BUG than corrupt memory.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/scsi/a100u2w.c

diff --git a/drivers/scsi/a100u2w.c b/drivers/scsi/a100u2w.c
index 1e8bdd4..f5051f4 100644
--- a/drivers/scsi/a100u2w.c
+++ b/drivers/scsi/a100u2w.c
@@ -866,6 +866,7 @@
 
 	count_sg = scsi_dma_map(cmd);
 	BUG_ON(count_sg < 0);
+	BUG_ON(count_sg > TOTAL_SG_ENTRY);
 
 	/* Build the scatter gather lists */
 	if (count_sg) {