scsi: Improve error messages more

Remove the "scsi-block:" prefix for error messages as suggested
by Markus.

Improve the previous patch by making the message the same for both
scsi-block and scsi-generic, including the strerror() output in both
and making an explicit reference to SG_IO.  Also s/can not/cannot/.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/scsi/scsi-disk.c

@@ -2458,26 +2458,27 @@ static int scsi_block_initfn(SCSIDevice *dev)
     int rc;
 
     if (!s->qdev.conf.bs) {
-        error_report("scsi-block: drive property not set");
+        error_report("drive property not set");
         return -1;
     }
 
     /* check we are using a driver managing SG_IO (version 3 and after) */
-    rc =  bdrv_ioctl(s->qdev.conf.bs, SG_GET_VERSION_NUM, &sg_version);
+    rc = bdrv_ioctl(s->qdev.conf.bs, SG_GET_VERSION_NUM, &sg_version);
     if (rc < 0) {
-        error_report("scsi-block: can not get version number: %s",
+        error_report("cannot get SG_IO version number: %s.  "
+                     "Is this a SCSI device?",
                      strerror(-rc));
         return -1;
     }
     if (sg_version < 30000) {
-        error_report("scsi-block: scsi generic interface too old");
+        error_report("scsi generic interface too old");
         return -1;
     }
 
     /* get device type from INQUIRY data */
     rc = get_device_type(s);
     if (rc < 0) {
-        error_report("scsi-block: INQUIRY failed");
+        error_report("INQUIRY failed");
         return -1;
     }
 

hw/scsi/scsi-generic.c

@@ -394,6 +394,7 @@ static void scsi_destroy(SCSIDevice *s)
 
 static int scsi_generic_initfn(SCSIDevice *s)
 {
+    int rc;
     int sg_version;
     struct sg_scsi_id scsiid;
 
@@ -412,8 +413,11 @@ static int scsi_generic_initfn(SCSIDevice *s)
     }
 
     /* check we are using a driver managing SG_IO (version 3 and after */
-    if (bdrv_ioctl(s->conf.bs, SG_GET_VERSION_NUM, &sg_version) < 0) {
-        error_report("scsi generic interface not supported");
+    rc = bdrv_ioctl(s->conf.bs, SG_GET_VERSION_NUM, &sg_version);
+    if (rc < 0) {
+        error_report("cannot get SG_IO version number: %s.  "
+                     "Is this a SCSI device?",
+                     strerror(-rc));
         return -1;
     }
     if (sg_version < 30000) {