From 80e0c41b896e1eeffc594416b4c2787ed29363b6 Mon Sep 17 00:00:00 2001
From: Steffen Maier <maier@linux.ibm.com>
Date: Fri, 15 Jun 2018 20:09:13 +0200
Subject: [PATCH] lstape: fix output without SCSI generic (sg)
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The default bash setting have nullglob disabled so if
$SCSI_DEV/scsi_generic*
aka
/sys/bus/scsi/devices/*:*:*:*/scsi_generic*
does not match anything, it leaves the glob pattern unmodified and
SG_DEV=$(basename $SG_DEV/*)
results in the literal:
*
If $SG_INQ exists, it invoked sg_inq with more than the one allowed
positional argument for a SCSI generic device node:
sg_inq /dev/*
Causing error messages and the usage of sg_inq to land in $TAPE_SERIAL.

To not have to rely on the nullglob setting, explicitly check for the
existence of $SCSI_DEV/scsi_generic before evaluating
SG_DEV=$(basename $SG_DEV/*).

Also handle availability of sg_inq but absence of scsi_generic
individually to provide the user with a hint if only sg is missing.

Suggested-by: Eric Farman <farman@linux.vnet.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Cc: Eric Farman <farman@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
---
 zconf/lstape   | 12 ++++++++++--
 zconf/lstape.8 |  8 +++++++-
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/zconf/lstape b/zconf/lstape
index 5501cb11..91609fbb 100755
--- a/zconf/lstape
+++ b/zconf/lstape
@@ -48,6 +48,9 @@ function PrintUsage() {
 	:		-v|--version
 	:			Display the version of the tools package and
 	:			the lstape command.
+	:
+	:$(basename $0) without the --ccw-only option causes extra SAN traffic
+	:for each SCSI tape or changer device by invoking the sg_inq command.
 	EOD
 }
 
@@ -249,11 +252,16 @@ function SysfsCreateListSCSI()
 		if [ -h $SG_DEV ]; then
 			# deprecated sysfs layout
 			SG_DEV=$(echo $SG_DEV | awk -F: '{print $NF}')
-		else
+		elif [ -d $SCSI_DEV/scsi_generic ]; then
 			SG_DEV=$(basename $SG_DEV/*)
+		else
+			SG_DEV=""
 		fi
 
-		if [ "$SG_INQ" != "" ]; then
+		if [ -z "$SG_DEV" ]; then
+			SG_DEV="N/A"
+			TAPE_SERIAL="NO/SG"
+		elif [ "$SG_INQ" != "" ]; then
 			TAPE_SERIAL=$(
 				sg_inq /dev/$SG_DEV |
 				awk '/serial/{print $NF}'
diff --git a/zconf/lstape.8 b/zconf/lstape.8
index 069a8588..80d54e53 100644
--- a/zconf/lstape.8
+++ b/zconf/lstape.8
@@ -36,7 +36,13 @@ IBM tape driver this would be "IBMtape" or "IBMchanger". If "N/A" is shown,
 the correct driver could not be obtained.
 
 The serial number of a SCSI tape can be displayed with the --verbose option. If
-there is no sg_inq command available "NO/INQ" is shown as the tape's serial.
+there is no sg_inq command available "NO/INQ" is shown as the serial number
+of the tape.
+If no SCSI generic (sg) kernel support is available, "NO/SG" is shown
+as the serial number of the tape and "N/A" for the "Generic" column.
+
+The lstape command without the --ccw-only option causes extra SAN traffic
+for each SCSI tape or changer device by invoking the sg_inq command.
 
 .SH OPTIONS
 .TP 8