camcontrol rescan all fails if there is no bus 0

[Ryan Stone]

If you issue a "camcontrol rescan all" on a system that does not have
scsi bus 0, camcontrol gets a EINVAL from a CAMIOCOMMAND ioctl and
exits after printing an error while trying to do a XPT_DEV_MATCH.
This is because camcontrol passes a bzero'd ccb to the ioctl without
ever setting the path_id, so CAM looks up path 0 and returns EINVAL if
that bus does not exist.

This is just slightly annoying if there are no CAM devices on the
system.  If you had a system with CAM devices, but no bus 0, then
camcontrol rescan all would always fail.  I'm not sure if it's
actually possible to skip path 0, though.

The following patch resolves the issue for me:
Index: camcontrol.c
===================================================================
--- camcontrol.c	(revision 214271)
+++ camcontrol.c	(working copy)
@@ -1519,6 +1519,7 @@ rescan_or_reset_bus(int bus, int rescan)
 	bzero(&(&matchccb.ccb_h)[1],
 	      sizeof(struct ccb_dev_match) - sizeof(struct ccb_hdr));
 	matchccb.ccb_h.func_code = XPT_DEV_MATCH;
+	matchccb.ccb_h.path_id = CAM_BUS_WILDCARD;
 	bufsize = sizeof(struct dev_match_result) * 20;
 	matchccb.cdm.match_buf_len = bufsize;
 	matchccb.cdm.matches=(struct dev_match_result *)malloc(bufsize);


(by the way, should I be using CAM_BUS_WILDCARD or CAM_XPT_PATH_ID?
By the name WILDCARD seems more appropriate but I see that camcontrol
uses CAM_XPT_PATH_ID in getdevtree.