[PATCH v2 10/15] libxl: add option to choose who executes hotplug scripts

[Roger Pau Monne <roger.pau@citrix.com>]

Add and option to xl.conf file to decide if hotplug scripts are
executed from the toolstack (xl) or from udev as it used to be in the
past.

This option is only introduced in this patch, but it has no effect
since the code to call hotplug scripts from libxl is introduced in a
latter patch.

This choice will be saved in "libxl/disable_udev", as specified in the
DISABLE_UDEV_PATH constant.

Changes since v1:

 * Used an auxiliary function to check for the current setting.

Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
---
 docs/man/xl.conf.pod.5       |    8 ++++++++
 tools/examples/xl.conf       |    5 +++++
 tools/libxl/libxl_create.c   |   31 ++++++++++++++++++++++++++++++-
 tools/libxl/libxl_internal.c |   19 +++++++++++++++++++
 tools/libxl/libxl_internal.h |    3 +++
 tools/libxl/libxl_types.idl  |    1 +
 tools/libxl/xl.c             |    4 ++++
 tools/libxl/xl.h             |    1 +
 tools/libxl/xl_cmdimpl.c     |    1 +
 9 files changed, 72 insertions(+), 1 deletions(-)

diff --git a/docs/man/xl.conf.pod.5 b/docs/man/xl.conf.pod.5
index 8bd45ea..72825a0 100644
--- a/docs/man/xl.conf.pod.5
+++ b/docs/man/xl.conf.pod.5
@@ -55,6 +55,14 @@ default.
 
 Default: C<1>
 
+=item B<run_hotplug_scripts=BOOLEAN>
+
+If disabled hotplug scripts will be called from udev, as it used to
+be in the previous releases. With the default option, hotplug scripts
+will be launched by xl directly.
+
+Default: C<1>
+
 =item B<lockfile="PATH">
 
 Sets the path to the lock file used by xl to serialise certain
diff --git a/tools/examples/xl.conf b/tools/examples/xl.conf
index 56d3b3b..75b00e0 100644
--- a/tools/examples/xl.conf
+++ b/tools/examples/xl.conf
@@ -12,3 +12,8 @@
 
 # default output format used by "xl list -l"
 #output_format="json"
+
+# default option to run hotplug scripts from xl
+# if disabled the old behaviour will be used, and hotplug scripts will be
+# launched by udev.
+#run_hotplug_scripts=1
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 076f755..15f94bd 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -398,7 +398,7 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_create_info *info,
                        uint32_t *domid)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
-    int flags, ret, rc;
+    int flags, ret, rc, nb_vm;
     char *uuid_string;
     char *dom_path, *vm_path, *libxl_path;
     struct xs_permissions roperm[2];
@@ -519,6 +519,35 @@ retry_transaction:
             libxl__sprintf(gc, "%s/hvmloader/generation-id-address", dom_path),
                         rwperm, ARRAY_SIZE(rwperm));
 
+    if (libxl_list_vm(ctx, &nb_vm) < 0) {
+        LOG(ERROR, "cannot get number of running guests");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    int hotplug_setting = libxl__hotplug_settings(gc, t);
+    if (libxl_defbool_val(info->run_hotplug_scripts) != hotplug_setting &&
+        (nb_vm - 1)) {
+        LOG(ERROR, "cannot change hotplug execution option once set, "
+                    "please shutdown all guests before changing it");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    if (libxl_defbool_val(info->run_hotplug_scripts)) {
+        rc = libxl__xs_write(gc, t, DISABLE_UDEV_PATH, "1");
+        if (rc) {
+            LOGE(ERROR, "unable to write %s = 1", DISABLE_UDEV_PATH);
+            goto out;
+        }
+    } else {
+        rc = xs_rm(ctx->xsh, t, DISABLE_UDEV_PATH);
+        if (rc) {
+            LOGE(ERROR, "unable to delete %s", DISABLE_UDEV_PATH);
+            goto out;
+        }
+    }
+
     xs_write(ctx->xsh, t, libxl__sprintf(gc, "%s/uuid", vm_path), uuid_string, strlen(uuid_string));
     xs_write(ctx->xsh, t, libxl__sprintf(gc, "%s/name", vm_path), info->name, strlen(info->name));
 
diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index b89aef7..bdf14d5 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -346,6 +346,25 @@ libxl_device_model_version libxl__device_model_version_running(libxl__gc *gc,
     return value;
 }
 
+int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t)
+{
+    int rc = 0;
+    char *val;
+
+    val = libxl__xs_read(gc, t, DISABLE_UDEV_PATH);
+    if (!val && errno != ENOENT) {
+        LOGE(ERROR, "cannot read %s from xenstore", DISABLE_UDEV_PATH);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    if (!val) val = "0";
+
+    rc = atoi(val);
+
+out:
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index d303123..dfbeb75 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -86,6 +86,7 @@
 #define STUBDOM_CONSOLE_SERIAL 3
 #define STUBDOM_SPECIAL_CONSOLES 3
 #define TAP_DEVICE_SUFFIX "-emu"
+#define DISABLE_UDEV_PATH "libxl/disable_udev"
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
 
@@ -1386,6 +1387,8 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc *gc, const char *s);
 _hidden libxl_device_model_version
 libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
 
+/* Check how executes hotplug script currently */
+int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t);
 
 /*
  * Calling context and GC for event-generating functions:
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 551e367..b1351de 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -220,6 +220,7 @@ libxl_domain_create_info = Struct("domain_create_info",[
     ("xsdata",       libxl_key_value_list),
     ("platformdata", libxl_key_value_list),
     ("poolid",       uint32),
+    ("run_hotplug_scripts",libxl_defbool),
     ], dir=DIR_IN)
 
 MemKB = UInt(64, init_val = "LIBXL_MEMKB_DEFAULT")
diff --git a/tools/libxl/xl.c b/tools/libxl/xl.c
index d4db1f8..d992c32 100644
--- a/tools/libxl/xl.c
+++ b/tools/libxl/xl.c
@@ -35,6 +35,7 @@
 xentoollog_logger_stdiostream *logger;
 int dryrun_only;
 int autoballoon = 1;
+libxl_defbool run_hotplug_scripts;
 char *lockfile;
 char *default_vifscript = NULL;
 char *default_bridge = NULL;
@@ -66,6 +67,9 @@ static void parse_global_config(const char *configfile,
     if (!xlu_cfg_get_long (config, "autoballoon", &l, 0))
         autoballoon = l;
 
+    libxl_defbool_setdefault(&run_hotplug_scripts, true);
+    xlu_cfg_get_defbool(config, "run_hotplug_scripts", &run_hotplug_scripts, 0);
+
     if (!xlu_cfg_get_string (config, "lockfile", &buf, 0))
         lockfile = strdup(buf);
     else {
diff --git a/tools/libxl/xl.h b/tools/libxl/xl.h
index 2b6714a..43d727a 100644
--- a/tools/libxl/xl.h
+++ b/tools/libxl/xl.h
@@ -109,6 +109,7 @@ void postfork(void);
 
 /* global options */
 extern int autoballoon;
+extern libxl_defbool run_hotplug_scripts;
 extern int dryrun_only;
 extern char *lockfile;
 extern char *default_vifscript;
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 46af9fb..c13c48b 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -562,6 +562,7 @@ static void parse_config_data(const char *configfile_filename_report,
         }
     }
 
+    c_info->run_hotplug_scripts = run_hotplug_scripts;
     c_info->type = LIBXL_DOMAIN_TYPE_PV;
     if (!xlu_cfg_get_string (config, "builder", &buf, 0) &&
         !strncmp(buf, "hvm", strlen(buf)))
-- 
1.7.7.5 (Apple Git-26)