make domain_create() return a proper error code

While triggered by the XSA-9 fix, this really is of more general use;
that fix just pointed out very sharply that the current situation
with all domain creation failures reported to user (tools) space as
-ENOMEM is very unfortunate (actively misleading users _and_ support
personnel).

Pull over the pointer <-> error code conversion infrastructure from
Linux, and use it in domain_create() and all it callers.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 0854f55bf5..eee74be50f 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -28,7 +28,7 @@
 #include <xen/softirq.h>
 #include <xen/trace.h>
 #include <xen/mm.h>
-#include <xen/errno.h>
+#include <xen/err.h>
 #include <xen/guest_access.h>
 #include <xen/multicall.h>
 #include <xen/cpu.h>
@@ -1323,7 +1323,7 @@ void __init scheduler_init(void)
         panic("scheduler returned error on init\n");
 
     idle_domain = domain_create(DOMID_IDLE, 0, 0);
-    BUG_ON(idle_domain == NULL);
+    BUG_ON(IS_ERR(idle_domain));
     idle_domain->vcpu = idle_vcpu;
     idle_domain->max_vcpus = nr_cpu_ids;
     if ( alloc_vcpu(idle_domain, 0, 0) == NULL )