SCSI: 3w-9xxx fix bug in sgl loading

commit 53ca3535 upstream.

This small patch fixes a bug in the 3w-9xxx driver where it would load
an invalid sgl address in the ioctl path even if request length was zero.
Signed-off-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/scsi/3w-9xxx.c

@@ -76,6 +76,7 @@
                  Fix bug in twa_get_param() on 4GB+.
                  Use pci_resource_len() for ioremap().
    2.26.02.012 - Add power management support.
+   2.26.02.013 - Fix bug in twa_load_sgl().
 */
 
 #include <linux/module.h>
@@ -100,7 +101,7 @@
 #include "3w-9xxx.h"
 
 /* Globals */
-#define TW_DRIVER_VERSION "2.26.02.012"
+#define TW_DRIVER_VERSION "2.26.02.013"
 static TW_Device_Extension *twa_device_extension_list[TW_MAX_SLOT];
 static unsigned int twa_device_extension_count;
 static int twa_major = -1;
@@ -1378,10 +1379,12 @@ static void twa_load_sgl(TW_Device_Extension *tw_dev, TW_Command_Full *full_comm
 		newcommand = &full_command_packet->command.newcommand;
 		newcommand->request_id__lunl =
 			cpu_to_le16(TW_REQ_LUN_IN(TW_LUN_OUT(newcommand->request_id__lunl), request_id));
-		newcommand->sg_list[0].address = TW_CPU_TO_SGL(dma_handle + sizeof(TW_Ioctl_Buf_Apache) - 1);
-		newcommand->sg_list[0].length = cpu_to_le32(length);
+		if (length) {
+			newcommand->sg_list[0].address = TW_CPU_TO_SGL(dma_handle + sizeof(TW_Ioctl_Buf_Apache) - 1);
+			newcommand->sg_list[0].length = cpu_to_le32(length);
+		}
 		newcommand->sgl_entries__lunh =
-			cpu_to_le16(TW_REQ_LUN_IN(TW_LUN_OUT(newcommand->sgl_entries__lunh), 1));
+			cpu_to_le16(TW_REQ_LUN_IN(TW_LUN_OUT(newcommand->sgl_entries__lunh), length ? 1 : 0));
 	} else {
 		oldcommand = &full_command_packet->command.oldcommand;
 		oldcommand->request_id = request_id;