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, 131 insertions, 18 deletions

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 5a07ffb35b..a94beabf08 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -58,6 +58,48 @@ int libxl__parse_backend_path(libxl__gc *gc,
     return libxl__device_kind_from_string(strkind, &dev->backend_kind);
 }
 
+static int libxl__num_devices(libxl__gc *gc, uint32_t domid)
+{
+    char *path;
+    unsigned int num_kinds, num_devs;
+    char **kinds = NULL, **devs = NULL;
+    int i, j, rc = 0;
+    libxl__device dev;
+    libxl__device_kind kind;
+    int numdevs = 0;
+
+    path = GCSPRINTF("/local/domain/%d/device", domid);
+    kinds = libxl__xs_directory(gc, XBT_NULL, path, &num_kinds);
+    if (!kinds) {
+        if (errno != ENOENT) {
+            LOGE(ERROR, "unable to get xenstore device listing %s", path);
+            rc = ERROR_FAIL;
+            goto out;
+        }
+        num_kinds = 0;
+    }
+    for (i = 0; i < num_kinds; i++) {
+        if (libxl__device_kind_from_string(kinds[i], &kind))
+            continue;
+
+        path = GCSPRINTF("/local/domain/%d/device/%s", domid, kinds[i]);
+        devs = libxl__xs_directory(gc, XBT_NULL, path, &num_devs);
+        if (!devs)
+            continue;
+        for (j = 0; j < num_devs; j++) {
+            path = GCSPRINTF("/local/domain/%d/device/%s/%s/backend",
+                             domid, kinds[i], devs[j]);
+            path = libxl__xs_read(gc, XBT_NULL, path);
+            if (path && libxl__parse_backend_path(gc, path, &dev) == 0) {
+                numdevs++;
+            }
+        }
+    }
+out:
+    if (rc) return rc;
+    return numdevs;
+}
+
 int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
         libxl__device *device, char **bents, char **fents)
 {
@@ -370,6 +412,37 @@ void libxl__prepare_ao_device(libxl__ao *ao, libxl__ao_device *aodev)
     aodev->dev = NULL;
     /* Initialize timer for QEMU Bodge */
     libxl__ev_time_init(&aodev->timeout);
+    aodev->active = 1;
+}
+
+void libxl__prepare_ao_devices(libxl__ao *ao, libxl__ao_devices *aodevs)
+{
+    AO_GC;
+
+    GCNEW_ARRAY(aodevs->array, aodevs->size);
+    for (int i = 0; i < aodevs->size; i++) {
+        aodevs->array[i].aodevs = aodevs;
+        libxl__prepare_ao_device(ao, &aodevs->array[i]);
+    }
+}
+
+void libxl__ao_devices_callback(libxl__egc *egc, libxl__ao_device *aodev)
+{
+    STATE_AO_GC(aodev->ao);
+    libxl__ao_devices *aodevs = aodev->aodevs;
+    int i, error = 0;
+
+    aodev->active = 0;
+    for (i = 0; i < aodevs->size; i++) {
+        if (aodevs->array[i].active)
+            return;
+
+        if (aodevs->array[i].rc)
+            error = aodevs->array[i].rc;
+    }
+
+    aodevs->callback(egc, aodevs, error);
+    return;
 }
 
 int libxl__device_destroy(libxl__gc *gc, libxl__device *dev)
@@ -386,16 +459,35 @@ int libxl__device_destroy(libxl__gc *gc, libxl__device *dev)
     return 0;
 }
 
-int libxl__devices_destroy(libxl__gc *gc, uint32_t domid)
+/* Callback for device destruction */
+
+static void devices_remove_callback(libxl__egc *egc, libxl__ao_devices *aodevs,
+                                    int rc);
+
+void libxl__devices_destroy(libxl__egc *egc, libxl__devices_remove_state *drs)
 {
+    STATE_AO_GC(drs->ao);
     libxl_ctx *ctx = libxl__gc_owner(gc);
+    uint32_t domid = drs->domid;
     char *path;
-    unsigned int num_kinds, num_devs;
+    unsigned int num_kinds, num_dev_xsentries;
     char **kinds = NULL, **devs = NULL;
-    int i, j;
-    libxl__device dev;
+    int i, j, numdev = 0, rc = 0;
+    libxl__device *dev;
+    libxl__ao_devices *aodevs = &drs->aodevs;
+    libxl__ao_device *aodev;
     libxl__device_kind kind;
 
+    aodevs->size = libxl__num_devices(gc, drs->domid);
+    if (aodevs->size < 0) {
+        LOG(ERROR, "unable to get number of devices for domain %u", drs->domid);
+        rc = aodevs->size;
+        goto out;
+    }
+
+    libxl__prepare_ao_devices(drs->ao, aodevs);
+    aodevs->callback = devices_remove_callback;
+
     path = libxl__sprintf(gc, "/local/domain/%d/device", domid);
     kinds = libxl__xs_directory(gc, XBT_NULL, path, &num_kinds);
     if (!kinds) {
@@ -411,19 +503,25 @@ int libxl__devices_destroy(libxl__gc *gc, uint32_t domid)
             continue;
 
         path = libxl__sprintf(gc, "/local/domain/%d/device/%s", domid, kinds[i]);
-        devs = libxl__xs_directory(gc, XBT_NULL, path, &num_devs);
+        devs = libxl__xs_directory(gc, XBT_NULL, path, &num_dev_xsentries);
         if (!devs)
             continue;
-        for (j = 0; j < num_devs; j++) {
+        for (j = 0; j < num_dev_xsentries; j++) {
             path = libxl__sprintf(gc, "/local/domain/%d/device/%s/%s/backend",
                                   domid, kinds[i], devs[j]);
             path = libxl__xs_read(gc, XBT_NULL, path);
-            if (path && libxl__parse_backend_path(gc, path, &dev) == 0) {
-                dev.domid = domid;
-                dev.kind = kind;
-                dev.devid = atoi(devs[j]);
-
-                libxl__device_destroy(gc, &dev);
+            GCNEW(dev);
+            if (path && libxl__parse_backend_path(gc, path, dev) == 0) {
+                aodev = &aodevs->array[numdev];
+                dev->domid = domid;
+                dev->kind = kind;
+                dev->devid = atoi(devs[j]);
+                aodev->action = DEVICE_DISCONNECT;
+                aodev->dev = dev;
+                aodev->callback = libxl__ao_devices_callback;
+                aodev->force = drs->force;
+                libxl__initiate_device_remove(egc, aodev);
+                numdev++;
             }
         }
     }
@@ -431,17 +529,22 @@ int libxl__devices_destroy(libxl__gc *gc, uint32_t domid)
     /* console 0 frontend directory is not under /local/domain/<domid>/device */
     path = libxl__sprintf(gc, "/local/domain/%d/console/backend", domid);
     path = libxl__xs_read(gc, XBT_NULL, path);
+    GCNEW(dev);
     if (path && strcmp(path, "") &&
-        libxl__parse_backend_path(gc, path, &dev) == 0) {
-        dev.domid = domid;
-        dev.kind = LIBXL__DEVICE_KIND_CONSOLE;
-        dev.devid = 0;
+        libxl__parse_backend_path(gc, path, dev) == 0) {
+        dev->domid = domid;
+        dev->kind = LIBXL__DEVICE_KIND_CONSOLE;
+        dev->devid = 0;
 
-        libxl__device_destroy(gc, &dev);
+        /* Currently console devices can be destroyed synchronously by just
+         * removing xenstore entries, this is what libxl__device_destroy does.
+         */
+        libxl__device_destroy(gc, dev);
     }
 
 out:
-    return 0;
+    if (!numdev) drs->callback(egc, drs, rc);
+    return;
 }
 
 /* Callbacks for device related operations */
@@ -645,6 +748,16 @@ out:
     return;
 }
 
+static void devices_remove_callback(libxl__egc *egc, libxl__ao_devices *aodevs,
+                                    int rc)
+{
+    libxl__devices_remove_state *drs = CONTAINER_OF(aodevs, *drs, aodevs);
+    STATE_AO_GC(drs->ao);
+
+    drs->callback(egc, drs, rc);
+    return;
+}
+
 int libxl__wait_for_device_model(libxl__gc *gc,
                                  uint32_t domid, char *state,
                                  libxl__spawn_starting *spawning,