libxl: convert libxl_domain_destroy to an async op

This change introduces some new structures, and breaks the mutual
dependency that libxl_domain_destroy and libxl__destroy_device_model
had. This is done by checking if the domid passed to
libxl_domain_destroy has a stubdom, and then having the bulk of the
destroy machinery in a separate function (libxl__destroy_domid) that
doesn't check for stubdom presence, since we check for it in the upper
level function. The reason behind this change is the need to use
structures for ao operations, and it was impossible to have two
different self-referencing structs.

All uses of libxl_domain_destroy have been changed, and either
replaced by the new libxl_domain_destroy ao function or by the
internal libxl__domain_destroy that can be used inside an already
running ao.

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

1 files changed, 115 insertions, 1 deletions

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 101e7fbcf5..562ca6173f 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -875,7 +875,6 @@ _hidden char *libxl__device_frontend_path(libxl__gc *gc, libxl__device *device);
 _hidden int libxl__parse_backend_path(libxl__gc *gc, const char *path,
                                       libxl__device *dev);
 _hidden int libxl__device_destroy(libxl__gc *gc, libxl__device *dev);
-_hidden int libxl__devices_destroy(libxl__gc *gc, uint32_t domid);
 _hidden int libxl__wait_for_backend(libxl__gc *gc, char *be_path, char *state);
 
 /*
@@ -1978,6 +1977,7 @@ typedef enum {
 } libxl__device_action;
 
 typedef struct libxl__ao_device libxl__ao_device;
+typedef struct libxl__ao_devices libxl__ao_devices;
 typedef void libxl__device_callback(libxl__egc*, libxl__ao_device*);
 
 /* This functions sets the necessary libxl__ao_device struct values to use
@@ -1996,6 +1996,20 @@ typedef void libxl__device_callback(libxl__egc*, libxl__ao_device*);
  */
 _hidden void libxl__prepare_ao_device(libxl__ao *ao, libxl__ao_device *aodev);
 
+/* Prepare a bunch of devices for addition/removal. Every ao_device in
+ * ao_devices is set to 'active', and the ao_device 'base' field is set to
+ * the one pointed by aodevs.
+ */
+_hidden void libxl__prepare_ao_devices(libxl__ao *ao,
+                                       libxl__ao_devices *aodevs);
+
+/* Generic callback to use when adding/removing several devices, this will
+ * check if the given aodev is the last one, and call the callback in the
+ * parent libxl__ao_devices struct, passing the appropriate error if found.
+ */
+_hidden void libxl__ao_devices_callback(libxl__egc *egc,
+                                        libxl__ao_device *aodev);
+
 struct libxl__ao_device {
     /* filled in by user */
     libxl__ao *ao;
@@ -2004,10 +2018,27 @@ struct libxl__ao_device {
     int force;
     libxl__device_callback *callback;
     /* private for implementation */
+    int active;
     int rc;
     libxl__ev_devstate backend_ds;
     /* Bodge for Qemu devices */
     libxl__ev_time timeout;
+    /* Used internally to have a reference to the upper libxl__ao_devices
+     * struct when present */
+    libxl__ao_devices *aodevs;
+};
+
+/* Helper struct to simply the plug/unplug of multiple devices at the same
+ * time.
+ *
+ * This structure holds several devices, and the callback is only called
+ * when all the devices inside of the array have finished.
+ */
+typedef void libxl__devices_callback(libxl__egc*, libxl__ao_devices*, int rc);
+struct libxl__ao_devices {
+    libxl__ao_device *array;
+    int size;
+    libxl__devices_callback *callback;
 };
 
 /*
@@ -2098,6 +2129,86 @@ struct libxl__ao_device {
 _hidden void libxl__initiate_device_remove(libxl__egc *egc,
                                            libxl__ao_device *aodev);
 
+/*----- Domain destruction -----*/
+
+/* Domain destruction has been split into two functions:
+ *
+ * libxl__domain_destroy is the main destroy function, which detects
+ * stubdoms and calls libxl__destroy_domid on the domain and its
+ * stubdom if present, creating a different libxl__destroy_domid_state
+ * for each one of them.
+ *
+ * libxl__destroy_domid actually destroys the domain, but it
+ * doesn't check for stubdomains, since that would involve
+ * recursion, which we want to avoid.
+ */
+
+typedef struct libxl__domain_destroy_state libxl__domain_destroy_state;
+typedef struct libxl__destroy_domid_state libxl__destroy_domid_state;
+typedef struct libxl__devices_remove_state libxl__devices_remove_state;
+
+typedef void libxl__domain_destroy_cb(libxl__egc *egc,
+                                      libxl__domain_destroy_state *dds,
+                                      int rc);
+
+typedef void libxl__domid_destroy_cb(libxl__egc *egc,
+                                     libxl__destroy_domid_state *dis,
+                                     int rc);
+
+typedef void libxl__devices_remove_callback(libxl__egc *egc,
+                                            libxl__devices_remove_state *drs,
+                                            int rc);
+
+struct libxl__devices_remove_state {
+    /* filled in by user */
+    libxl__ao *ao;
+    uint32_t domid;
+    libxl__devices_remove_callback *callback;
+    int force; /* libxl_device_TYPE_destroy rather than _remove */
+    /* private */
+    libxl__ao_devices aodevs;
+    int num_devices;
+};
+
+struct libxl__destroy_domid_state {
+    /* filled in by user */
+    libxl__ao *ao;
+    uint32_t domid;
+    libxl__domid_destroy_cb *callback;
+    /* private to implementation */
+    libxl__devices_remove_state drs;
+};
+
+struct libxl__domain_destroy_state {
+    /* filled by the user */
+    libxl__ao *ao;
+    uint32_t domid;
+    libxl__domain_destroy_cb *callback;
+    /* Private */
+    int rc;
+    uint32_t stubdomid;
+    libxl__destroy_domid_state stubdom;
+    int stubdom_finished;
+    libxl__destroy_domid_state domain;
+    int domain_finished;
+};
+
+/*
+ * Entry point for domain destruction
+ * This function checks for stubdom presence and then calls
+ * libxl__destroy_domid on the passed domain and its stubdom if found.
+ */
+_hidden void libxl__domain_destroy(libxl__egc *egc,
+                                   libxl__domain_destroy_state *dds);
+
+/* Used to destroy a domain with the passed id (it doesn't check for stubs) */
+_hidden void libxl__destroy_domid(libxl__egc *egc,
+                                  libxl__destroy_domid_state *dis);
+
+/* Entry point for devices destruction */
+_hidden void libxl__devices_destroy(libxl__egc *egc,
+                                    libxl__devices_remove_state *drs);
+
 /*----- device model creation -----*/
 
 /* First layer; wraps libxl__spawn_spawn. */
@@ -2131,6 +2242,7 @@ typedef struct {
     libxl_domain_config dm_config;
     libxl__domain_build_state dm_state;
     libxl__dm_spawn_state pvqemu;
+    libxl__destroy_domid_state dis;
 } libxl__stub_dm_spawn_state;
 
 _hidden void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state*);
@@ -2158,6 +2270,8 @@ struct libxl__domain_create_state {
         /* If we're not doing stubdom, we use only dmss.dm,
          * for the non-stubdom device model. */
     libxl__save_helper_state shs;
+    /* necessary if the domain creation failed and we have to destroy it */
+    libxl__domain_destroy_state dds;
 };
 
 /*----- Domain suspend (save) functions -----*/