Don't attempt to set the read or write caches on usb disks. It

breaks at least one previously working device, as discovered by
naddy@. dlg@ confirmed other kernels also avoid attempting this
operation on usb disks.

ok dlg@ deraadt@

diff --git a/sys/scsi/sd.c b/sys/scsi/sd.c
index 98a44ad..29db37f 100644 (file)
--- a/sys/scsi/sd.c
+++ b/sys/scsi/sd.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: sd.c,v 1.204 2010/07/07 03:53:07 marco Exp $  */
+/*     $OpenBSD: sd.c,v 1.205 2010/08/03 19:37:17 krw Exp $    */
 /*     $NetBSD: sd.c,v 1.111 1997/04/02 02:29:41 mycroft Exp $ */
 
 /*-
@@ -1040,6 +1040,9 @@ sd_ioctl_cache(struct sd_softc *sc, long cmd, struct dk_cache *dkc)
        int big;
        int rv;
 
+       if (ISSET(sc->sc_link->flags, SDEV_UMASS))
+               return (EOPNOTSUPP);
+
        /* see if the adapter has special handling */
        rv = scsi_do_ioctl(sc->sc_link, cmd, (caddr_t)dkc, 0);
        if (rv != ENOTTY) {