Xen devel - May 2012 - [PATCH] libxl: set guest_domid even if libxl__domain_make fails

This is needed in order to perform the domain destruction if
libxl__domain_make fails.

Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
---
To be applied after IanJ libxl: subprocess handling series

 tools/libxl/libxl_create.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 928a48c..788e553 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -607,6 +607,7 @@ static void initiate_domain_create(libxl__egc *egc,
     ret = libxl__domain_make(gc, &d_config->c_info, &domid);
     if (ret) {
         LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "cannot make domain: %d",
ret);
+        dcs->guest_domid = domid;
         ret = ERROR_FAIL;
         goto error_out;
     }
-- 
1.7.7.5 (Apple Git-26)

Roger Pau Monne writes ("[PATCH] libxl: set guest_domid even if
libxl__domain_make fails"):
> This is needed in order to perform the domain destruction if
> libxl__domain_make fails.
>      ret = libxl__domain_make(gc, &d_config->c_info, &domid);
>      if (ret) {
>          LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "cannot make domain:
%d", ret);
> +        dcs->guest_domid = domid;
>          ret = ERROR_FAIL;
>          goto error_out;
This is a bit odd.  The documentation for libxl__domain_make says:

   /* from xl_create */
   _hidden int libxl__domain_make(libxl__gc *gc,
                                  libxl_domain_create_info *info,
                                  uint32_t *domid);

Yes, that''s it.  So apparently this function does actually create the
domain on error ?  Oh wait I see there is a doc comment but it''s next
to the definition.

   /* on entry, libxl_domid_valid_guest(domid) must be false;
    * on exit (even error exit), domid may be valid and refer to a domain */

So yes, that''s correct.

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Ian.

Roger Pau Monne writes ("[Xen-devel] [PATCH] libxl: set guest_domid even if
libxl__domain_make fails"):
> This is needed in order to perform the domain destruction if
> libxl__domain_make fails.
Thanks, I have included this in my series in the form below.

From: Roger Pau Monne <roger.pau@citrix.com>
Subject: [PATCH] libxl: set guest_domid even if libxl__domain_make fails

This is needed in order to perform the domain destruction if
libxl__domain_make fails.

Also move doc comment about error behaviour of libxl__domain_make from
implementation to declaration.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

---
 tools/libxl/libxl_create.c   |    3 +--
 tools/libxl/libxl_internal.h |    4 ++++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 0f17202..447d8ba 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -396,8 +396,6 @@ out:
 
 int libxl__domain_make(libxl__gc *gc, libxl_domain_create_info *info,
                        uint32_t *domid)
- /* on entry, libxl_domid_valid_guest(domid) must be false;
-  * on exit (even error exit), domid may be valid and refer to a domain */
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     int flags, ret, rc;
@@ -600,6 +598,7 @@ static void initiate_domain_create(libxl__egc *egc,
     ret = libxl__domain_make(gc, &d_config->c_info, &domid);
     if (ret) {
         LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "cannot make domain: %d",
ret);
+        dcs->guest_domid = domid;
         ret = ERROR_FAIL;
         goto error_out;
     }
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 90b08ef..84bfbc6 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1073,9 +1073,13 @@ _hidden void libxl__exec(int stdinfd, int stdoutfd, int
stderrfd,
                const char *arg0, char **args); // logs errors, never returns
 
 /* from xl_create */
+
+ /* on entry, libxl_domid_valid_guest(domid) must be false;
+  * on exit (even error exit), domid may be valid and refer to a domain */
 _hidden int libxl__domain_make(libxl__gc *gc,
                                libxl_domain_create_info *info,
                                uint32_t *domid);
+
 _hidden int libxl__domain_build(libxl__gc *gc,
                                 libxl_domain_build_info *info,
                                 uint32_t domid,
-- 
tg: (3aaba1c..) t/xen/xl.create-do-destroy (depends on: t/xen/xl.event.spawn)