Add zone_get_hostid() function

Minimal support added for the zone_get_hostid() function.  Only
global zones are supported therefore this function must be called
with a NULL argumment.  Additionally, I've added the HW_HOSTID_LEN
define and updated all instances where a hard coded magic value
of 11 was used; "A good riddance of bad rubbish!"

include/sys/proc.h

@@ -33,6 +33,7 @@
 #include <linux/sysctl.h>
 #include <linux/seq_file.h>
 #include <sys/sysmacros.h>
+#include <sys/systeminfo.h>
 #include <sys/kmem.h>
 #include <sys/mutex.h>
 #include <sys/kstat.h>

include/sys/sysmacros.h

@@ -143,6 +143,7 @@ extern int p0;
 
 /* Missing misc functions */
 extern int highbit(unsigned long i);
+extern uint32_t zone_get_hostid(void *zone);
 
 #define makedevice(maj,min) makedev(maj,min)
 

include/sys/systeminfo.h

@@ -1,4 +1,9 @@
 #ifndef _SPL_SYSTEMINFO_H
 #define _SPL_SYSTEMINFO_H
 
+#define HW_INVALID_HOSTID	0xFFFFFFFF	/* an invalid hostid */
+#define HW_HOSTID_LEN		11		/* minimum buffer size needed */
+						/* to hold a decimal or hex */
+						/* hostid string */
+
 #endif /* SPL_SYSTEMINFO_H */

module/spl/spl-generic.c

@@ -25,6 +25,7 @@
  */
 
 #include <sys/sysmacros.h>
+#include <sys/systeminfo.h>
 #include <sys/vmsystm.h>
 #include <sys/vnode.h>
 #include <sys/kmem.h>
@@ -47,7 +48,7 @@ char spl_version[16] = "SPL v" VERSION;
 long spl_hostid = 0;
 EXPORT_SYMBOL(spl_hostid);
 
-char hw_serial[11] = "<none>";
+char hw_serial[HW_HOSTID_LEN] = "<none>";
 EXPORT_SYMBOL(hw_serial);
 
 int p0 = 0;
@@ -253,6 +254,21 @@ set_hostid(void)
 	return call_usermodehelper(sh_path, argv, envp, 1);
 }
 
+uint32_t
+zone_get_hostid(void *zone)
+{
+	unsigned long hostid;
+
+	/* Only the global zone is supported */
+	ASSERT(zone == NULL);
+
+	if (ddi_strtoul(hw_serial, NULL, HW_HOSTID_LEN-1, &hostid) != 0)
+		return HW_INVALID_HOSTID;
+
+	return (uint32_t)hostid;
+}
+EXPORT_SYMBOL(zone_get_hostid);
+
 static int __init spl_init(void)
 {
 	int rc = 0;

module/spl/spl-proc.c

@@ -470,7 +470,8 @@ proc_dohostid(struct ctl_table *table, int write, struct file *filp,
 			RETURN(-EINVAL);
 
 		spl_hostid = (long)val;
-                (void)snprintf(hw_serial, 11, "%u", (val >= 0) ? val : -val);
+                (void)snprintf(hw_serial, HW_HOSTID_LEN-1, "%u",
+			       (val >= 0) ? val : -val);
                 *ppos += *lenp;
         } else {
                 len = snprintf(str, sizeof(str), "%lx", spl_hostid);