If a device says a MODE SENSE command worked fine, do *not* try a MODE

SENSE BIG command even if no page data was returned.  Just accept the
fact that the device does not have any such page data.

This is more in line with the spec, and unbreaks devices (like the
Neodio 8-in-1 USB Card Reader donated by Manuel Pata) which freak out
when getting a MODE SENSE BIG.

Should not break any 'working' device.

ok pedro@ dlg@ marco@ 'Looks correct.' miod@

1 files changed, 12 insertions, 2 deletions

diff --git a/sys/scsi/scsi_base.c b/sys/scsi/scsi_base.c
index 7719deef1b1..3f1399320f0 100644
--- a/sys/scsi/scsi_base.c
+++ b/sys/scsi/scsi_base.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: scsi_base.c,v 1.100 2006/05/07 00:20:05 krw Exp $	*/
+/*	$OpenBSD: scsi_base.c,v 1.101 2006/05/07 20:50:21 krw Exp $	*/
 /*	$NetBSD: scsi_base.c,v 1.43 1997/04/02 02:29:36 mycroft Exp $	*/
 
 /*
@@ -516,8 +516,18 @@ scsi_do_mode_sense(sc_link, page, buf, page_data, density, block_count,
 		 */
 		error = scsi_mode_sense(sc_link, 0, page, &buf->hdr,
 		    sizeof(*buf), flags, 20000);
-		if (error == 0 && buf->hdr.data_length > 2) {
+		if (error == 0) {
 			*page_data = scsi_mode_sense_page(&buf->hdr, page_len);
+			if (*page_data == NULL)
+				/*
+				 * XXX
+				 * Page data may be invalid (e.g. all zeros)
+				 * but we accept the device's word that this is
+				 * the best it can do. Some devices will freak
+				 * out if their word is not accepted and 
+				 * MODE_SENSE_BIG is attempted.
+				 */
+				return (0);
 			offset = sizeof(struct scsi_mode_header);
 			blk_desc_len = buf->hdr.blk_desc_len;
 			goto blk_desc;