[Qemu-devel] [PATCH] xen-hvm.c: Improve the return method for xen_hvm_init()

[Chen Gang <gang.chen.5i5j@gmail.com>]

When failure occurs, it need use "return -1" instead of exit(1), so can
let upper caller has chance to print failure information, too, then user
can know the failure result more clearly.

xen_hvm_init() may also return -errno, which may let upper caller think
more (e.g. free some other related resources and try again), although at
present, all related upper callers still exit(1).

It is not a normal function which does not release related resources, if
return -1. So need give the related comments for it.

It passes common test under fedora 20 x86_64:

  "./configure --enable-xen && make -j4 && make check"
  execute result: "echo $? == 0".

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 xen-hvm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen-hvm.c b/xen-hvm.c
index 0d09940..35efec0 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -978,6 +978,7 @@ static void xen_wakeup_notifier(Notifier *notifier, void *data)
     xc_set_hvm_param(xen_xc, xen_domid, HVM_PARAM_ACPI_S_STATE, 0);
 }
 
+/* return value:  0 is OK, -errno is failure, -1 is critical issue -- exit(1) */
 int xen_hvm_init(ram_addr_t *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
                  MemoryRegion **ram_memory)
 {
@@ -998,6 +999,7 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
     state->xenstore = xs_daemon_open();
     if (state->xenstore == NULL) {
         perror("xen: xenstore open");
+        xc_evtchn_close(state->xce_handle);
         g_free(state);
         return -errno;
     }
@@ -1069,7 +1071,7 @@ int xen_hvm_init(ram_addr_t *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
     /* Initialize backend core & drivers */
     if (xen_be_init() != 0) {
         fprintf(stderr, "%s: xen backend core setup failed\n", __FUNCTION__);
-        exit(1);
+        return -1;
     }
     xen_be_register("console", &xen_console_ops);
     xen_be_register("vkbd", &xen_kbdmouse_ops);
-- 
1.9.3