libxl: convert libxl_device_disk_add to an async op

This patch converts libxl_device_disk_add to an ao operation that
waits for device backend to reach state XenbusStateInitWait and then
marks the operation as completed. This is not really useful now, but
will be used by later patches that will launch hotplug scripts after
we reached the desired xenbus state.

As usual, libxl_device_disk_add callers have been modified, and the
internal function libxl__device_disk_add has been used if the call was
inside an already running ao.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
[ ijc -- drop hunk modifying libxl_cdrom_insert which is not needed after
         25670:3666e9712eaf "libxl: make libxl_cdrom_insert async" ]
Committed-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 102 insertions, 37 deletions

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 900eac1d1f..85475586ba 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1785,16 +1785,18 @@ int libxl__device_from_disk(libxl__gc *gc, uint32_t domid,
  * The passed get_vdev function is also in charge of printing
  * the corresponding error message when appropiate.
  */
-static int device_disk_add(libxl__gc *gc, uint32_t domid,
+static void device_disk_add(libxl__egc *egc, uint32_t domid,
                            libxl_device_disk *disk,
+                           libxl__ao_device *aodev,
                            char *get_vdev(libxl__gc *, void *,
                                           xs_transaction_t),
                            void *get_vdev_user)
 {
+    STATE_AO_GC(aodev->ao);
     flexarray_t *front = NULL;
     flexarray_t *back = NULL;
     char *dev;
-    libxl__device device;
+    libxl__device *device;
     int major, minor, rc;
     libxl_ctx *ctx = gc->owner;
     xs_transaction_t t = XBT_NULL;
@@ -1837,7 +1839,8 @@ static int device_disk_add(libxl__gc *gc, uint32_t domid,
             goto out_free;
         }
 
-        rc = libxl__device_from_disk(gc, domid, disk, &device);
+        GCNEW(device);
+        rc = libxl__device_from_disk(gc, domid, disk, device);
         if (rc != 0) {
             LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Invalid or unsupported"
                    " virtual disk identifier %s", disk->vdev);
@@ -1855,7 +1858,7 @@ static int device_disk_add(libxl__gc *gc, uint32_t domid,
                 flexarray_append(back, "params");
                 flexarray_append(back, dev);
 
-                assert(device.backend_kind == LIBXL__DEVICE_KIND_VBD);
+                assert(device->backend_kind == LIBXL__DEVICE_KIND_VBD);
                 break;
             case LIBXL_DISK_BACKEND_TAP:
                 dev = libxl__blktap_devpath(gc, disk->pdev_path, disk->format);
@@ -1876,7 +1879,7 @@ static int device_disk_add(libxl__gc *gc, uint32_t domid,
                 flexarray_append(back, "params");
                 flexarray_append(back, libxl__sprintf(gc, "%s:%s",
                               libxl__device_disk_string_of_format(disk->format), disk->pdev_path));
-                assert(device.backend_kind == LIBXL__DEVICE_KIND_QDISK);
+                assert(device->backend_kind == LIBXL__DEVICE_KIND_QDISK);
                 break;
             default:
                 LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "unrecognized disk backend type: %d\n", disk->backend);
@@ -1908,11 +1911,11 @@ static int device_disk_add(libxl__gc *gc, uint32_t domid,
         flexarray_append(front, "state");
         flexarray_append(front, libxl__sprintf(gc, "%d", 1));
         flexarray_append(front, "virtual-device");
-        flexarray_append(front, libxl__sprintf(gc, "%d", device.devid));
+        flexarray_append(front, libxl__sprintf(gc, "%d", device->devid));
         flexarray_append(front, "device-type");
         flexarray_append(front, disk->is_cdrom ? "cdrom" : "disk");
 
-        libxl__device_generic_add(gc, t, &device,
+        libxl__device_generic_add(gc, t, device,
                             libxl__xs_kvs_of_flexarray(gc, back, back->count),
                             libxl__xs_kvs_of_flexarray(gc, front, front->count));
 
@@ -1921,6 +1924,10 @@ static int device_disk_add(libxl__gc *gc, uint32_t domid,
         if (rc < 0) goto out_free;
     }
 
+    aodev->dev = device;
+    aodev->action = DEVICE_CONNECT;
+    libxl__wait_device_connection(egc, aodev);
+
     rc = 0;
 
 out_free:
@@ -1928,21 +1935,15 @@ out_free:
     flexarray_free(front);
 out:
     libxl__xs_transaction_abort(gc, &t);
-    return rc;
-}
-
-int libxl__device_disk_add(libxl__gc *gc, uint32_t domid,
-                           libxl_device_disk *disk)
-{
-    return device_disk_add(gc, domid, disk, NULL, NULL);
+    aodev->rc = rc;
+    if (rc) aodev->callback(egc, aodev);
+    return;
 }
 
-int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid, libxl_device_disk *disk)
+void libxl__device_disk_add(libxl__egc *egc, uint32_t domid,
+                           libxl_device_disk *disk, libxl__ao_device *aodev)
 {
-    GC_INIT(ctx);
-    int rc = libxl__device_disk_add(gc, domid, disk);
-    GC_FREE;
-    return rc;
+    device_disk_add(egc, domid, disk, aodev, NULL, NULL);
 }
 
 static void libxl__device_disk_from_xs_be(libxl__gc *gc,
@@ -2252,14 +2253,17 @@ static char * libxl__alloc_vdev(libxl__gc *gc, void *get_vdev_user,
     return NULL;
 }
 
+/* Callbacks */
+
+static void local_device_attach_cb(libxl__egc *egc, libxl__ao_device *aodev);
+
 void libxl__device_disk_local_initiate_attach(libxl__egc *egc,
                                      libxl__disk_local_state *dls)
 {
     STATE_AO_GC(dls->ao);
     libxl_ctx *ctx = CTX;
-    char *dev = NULL, *be_path = NULL;
+    char *dev = NULL;
     int rc;
-    libxl__device device;
     const libxl_device_disk *in_disk = dls->in_disk;
     libxl_device_disk *disk = &dls->disk;
     const char *blkdev_start = dls->blkdev_start;
@@ -2306,14 +2310,12 @@ void libxl__device_disk_local_initiate_attach(libxl__egc *egc,
             break;
         case LIBXL_DISK_BACKEND_QDISK:
             if (disk->format != LIBXL_DISK_FORMAT_RAW) {
-                if (device_disk_add(gc, LIBXL_TOOLSTACK_DOMID, disk,
-                                    libxl__alloc_vdev,
-                                    (void *) blkdev_start)) {
-                    LOG(ERROR, "libxl_device_disk_add failed");
-                    rc = ERROR_FAIL;
-                    goto out;
-                }
-                dev = GCSPRINTF("/dev/%s", disk->vdev);
+                libxl__prepare_ao_device(ao, &dls->aodev);
+                dls->aodev.callback = local_device_attach_cb;
+                device_disk_add(egc, LIBXL_TOOLSTACK_DOMID, disk,
+                                &dls->aodev, libxl__alloc_vdev,
+                                (void *) blkdev_start);
+                return;
             } else {
                 dev = disk->pdev_path;
             }
@@ -2326,15 +2328,48 @@ void libxl__device_disk_local_initiate_attach(libxl__egc *egc,
             goto out;
     }
 
-    if (disk->vdev != NULL) {
-        rc = libxl__device_from_disk(gc, LIBXL_TOOLSTACK_DOMID, disk, &device);
-        if (rc < 0)
-            goto out;
-        be_path = libxl__device_backend_path(gc, &device);
-        rc = libxl__wait_for_backend(gc, be_path, "4");
-        if (rc < 0)
-            goto out;
+    if (dev != NULL)
+        dls->diskpath = strdup(dev);
+
+    dls->callback(egc, dls, 0);
+    return;
+
+ out:
+    assert(rc);
+    dls->rc = rc;
+    libxl__device_disk_local_initiate_detach(egc, dls);
+    dls->callback(egc, dls, rc);
+}
+
+static void local_device_attach_cb(libxl__egc *egc, libxl__ao_device *aodev)
+{
+    STATE_AO_GC(aodev->ao);
+    libxl__disk_local_state *dls = CONTAINER_OF(aodev, *dls, aodev);
+    char *dev = NULL, *be_path = NULL;
+    int rc;
+    libxl__device device;
+    libxl_device_disk *disk = &dls->disk;
+
+    rc = aodev->rc;
+    if (rc) {
+        LOGE(ERROR, "unable to %s %s with id %u",
+                    aodev->action == DEVICE_CONNECT ? "add" : "remove",
+                    libxl__device_kind_to_string(aodev->dev->kind),
+                    aodev->dev->devid);
+        goto out;
     }
+
+    dev = GCSPRINTF("/dev/%s", disk->vdev);
+    LOG(DEBUG, "locally attaching qdisk %s", dev);
+
+    rc = libxl__device_from_disk(gc, LIBXL_TOOLSTACK_DOMID, disk, &device);
+    if (rc < 0)
+        goto out;
+    be_path = libxl__device_backend_path(gc, &device);
+    rc = libxl__wait_for_backend(gc, be_path, "4");
+    if (rc < 0)
+        goto out;
+
     if (dev != NULL)
         dls->diskpath = libxl__strdup(gc, dev);
 
@@ -3058,6 +3093,36 @@ DEFINE_DEVICE_REMOVE(vfb, destroy, 1)
 
 /******************************************************************************/
 
+/* Macro for defining device addition functions in a compact way */
+/* The following functions are defined:
+ * libxl_device_disk_add
+ */
+
+#define DEFINE_DEVICE_ADD(type)                                         \
+    int libxl_device_##type##_add(libxl_ctx *ctx,                       \
+        uint32_t domid, libxl_device_##type *type,                      \
+        const libxl_asyncop_how *ao_how)                                \
+    {                                                                   \
+        AO_CREATE(ctx, domid, ao_how);                                  \
+        libxl__ao_device *aodev;                                        \
+                                                                        \
+        GCNEW(aodev);                                                   \
+        libxl__prepare_ao_device(ao, aodev);                            \
+        aodev->callback = device_addrm_aocomplete;                      \
+        libxl__device_##type##_add(egc, domid, type, aodev);            \
+                                                                        \
+        return AO_INPROGRESS;                                           \
+    }
+
+/* Define alladd functions and undef the macro */
+
+/* disk */
+DEFINE_DEVICE_ADD(disk)
+
+#undef DEFINE_DEVICE_ADD
+
+/******************************************************************************/
+
 int libxl_domain_setmaxmem(libxl_ctx *ctx, uint32_t domid, uint32_t max_memkb)
 {
     GC_INIT(ctx);