[PATCH v5 04/10] libxl: convert libxl_device_disk_add to an asyn op

Roger Pau Monne
Wed, 30 May 2012 13:07:49 -0000

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 latter 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.

Changes since v4:

 * Added more comments about libxl__device_disk_add and
   libxl__add_disks.

 * Removed stray hunk in Makefile.

 * Fixed _prepare call libxl__add_disks (separate into a different
   loop).

 * Moved some code to check if disks have finished to a macro that
   generates a custom function, which will also be used for vif
   interfaces.

Changes since v2:

 * Remove state read from libxl__initiate_device_add

Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
---
 tools/libxl/libxl.c          |   50 ++++++++++++++++++++++++--------
 tools/libxl/libxl.h          |    4 ++-
 tools/libxl/libxl_create.c   |   44 ++++++++++++++++++++++------
 tools/libxl/libxl_device.c   |   65 ++++++++++++++++++++++++++++++++++++++++++
 tools/libxl/libxl_dm.c       |   63 +++++++++++++++++++++++++++++++---------
 tools/libxl/libxl_internal.h |   52 +++++++++++++++++++++++++++++++++
 tools/libxl/xl_cmdimpl.c     |    2 +-
 7 files changed, 242 insertions(+), 38 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 4044b9e..b674557 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1540,13 +1540,31 @@ static int libxl__device_from_disk(libxl__gc *gc,
uint32_t domid,
     return 0;
 }

-int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid, libxl_device_disk
*disk)
+int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
+                          libxl_device_disk *disk,
+                          const libxl_asyncop_how *ao_how)
 {
-    GC_INIT(ctx);
+    AO_CREATE(ctx, domid, ao_how);
+    libxl__ao_device *device;
+
+    GCNEW(device);
+    libxl__prepare_ao_device(device, ao, NULL);
+    device->callback = device_addrm_aocomplete;
+    libxl__device_disk_add(egc, domid, disk, device);
+
+    return AO_INPROGRESS;
+}
+
+void libxl__device_disk_add(libxl__egc *egc, uint32_t domid,
+                            libxl_device_disk *disk,
+                            libxl__ao_device *aodev)
+{
+    STATE_AO_GC(aodev->ao);
+    libxl_ctx *ctx = CTX;
     flexarray_t *front;
     flexarray_t *back;
     char *dev;
-    libxl__device device;
+    libxl__device *device;
     int major, minor, rc;

     rc = libxl__device_disk_setdefault(gc, disk);
@@ -1570,7 +1588,8 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *dis
         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);
@@ -1588,7 +1607,7 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *dis
             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);
@@ -1609,7 +1628,7 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *dis
             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);
@@ -1641,22 +1660,27 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t
domid, libxl_device_disk *dis
     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, &device,
+    libxl__device_generic_add(gc, device,
                              libxl__xs_kvs_of_flexarray(gc, back,
back->count),
                              libxl__xs_kvs_of_flexarray(gc, front,
front->count));

+    aodev->dev = device;
+    aodev->action = DEVICE_CONNECT;
+    libxl__initiate_device_add(egc, aodev);
+
     rc = 0;

 out_free:
     flexarray_free(back);
     flexarray_free(front);
 out:
-    GC_FREE;
-    return rc;
+    aodev->rc = rc;
+    if (rc) aodev->callback(egc, aodev);
+    return;
 }

 static void libxl__device_disk_from_xs_be(libxl__gc *gc,
@@ -1859,11 +1883,13 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *disk)
     ret = 0;

     libxl_device_disk_remove(ctx, domid, disks + i, 0);
-    libxl_device_disk_add(ctx, domid, disk);
+    /* fixme-ao */
+    libxl_device_disk_add(ctx, domid, disk, 0);
     stubdomid = libxl_get_stubdom_id(ctx, domid);
     if (stubdomid) {
         libxl_device_disk_remove(ctx, stubdomid, disks + i, 0);
-        libxl_device_disk_add(ctx, stubdomid, disk);
+        /* fixme-ao */
+        libxl_device_disk_add(ctx, stubdomid, disk, 0);
     }
 out:
     for (i = 0; i < num; i++)
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index d5dc2a0..ff0078d 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -638,7 +638,9 @@ void libxl_vminfo_list_free(libxl_vminfo *list, int nr);
  */

 /* Disks */
-int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid, libxl_device_disk
*disk);
+int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid,
+                          libxl_device_disk *disk,
+                          const libxl_asyncop_how *ao_how);
 int libxl_device_disk_remove(libxl_ctx *ctx, uint32_t domid,
                              libxl_device_disk *disk,
                              const libxl_asyncop_how *ao_how);
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 1df116e..2dc1cee 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -577,6 +577,14 @@ static void domcreate_bootloader_done(libxl__egc *egc,
                                       libxl__bootloader_state *bl,
                                       int rc);

+static void domcreate_launch_dm(libxl__egc *egc,
+                                libxl__domain_create_state *dcs,
+                                int rc);
+
+DEFINE_DEVICES_CALLBACK(domcreate_disk_connected,
+                        libxl__domain_create_state,
+                        devices, num_devices, domcreate_launch_dm)
+
 static void domcreate_console_available(libxl__egc *egc,
                                         libxl__domain_create_state *dcs);

@@ -677,7 +685,6 @@ static void domcreate_bootloader_done(libxl__egc *egc,
 {
     libxl__domain_create_state *dcs = CONTAINER_OF(bl, *dcs, bl);
     STATE_AO_GC(bl->ao);
-    int i;

     /* convenience aliases */
     const uint32_t domid = dcs->guest_domid;
@@ -716,15 +723,34 @@ static void domcreate_bootloader_done(libxl__egc *egc,

     store_libxl_entry(gc, domid, &d_config->b_info);

-    for (i = 0; i < d_config->num_disks; i++) {
-        ret = libxl_device_disk_add(ctx, domid, &d_config->disks[i]);
-        if (ret) {
-            LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
-                       "cannot add disk %d to domain: %d", i, ret);
-            ret = ERROR_FAIL;
-            goto error_out;
-        }
+    dcs->num_devices = d_config->num_disks;
+    libxl__add_disks(egc, ao, domid, d_config, &dcs->devices,
+                     domcreate_disk_connected);
+
+    return;
+
+ error_out:
+    assert(ret);
+    domcreate_complete(egc, dcs, ret);
+}
+
+static void domcreate_launch_dm(libxl__egc *egc,
+                                libxl__domain_create_state *dcs, int rc)
+{
+    STATE_AO_GC(dcs->ao);
+    int i, ret = 0;
+
+    /* convenience aliases */
+    const uint32_t domid = dcs->guest_domid;
+    libxl_domain_config *const d_config = dcs->guest_config;
+    libxl__domain_build_state *const state = &dcs->build_state;
+    libxl_ctx *const ctx = CTX;
+
+    if (rc) {
+        LOG(ERROR, "error connecting disk devices");
+        goto error_out;
     }
+
     for (i = 0; i < d_config->num_vifs; i++) {
         ret = libxl_device_nic_add(ctx, domid, &d_config->vifs[i]);
         if (ret) {
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 882e647..0beb4bb 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -426,6 +426,41 @@ int libxl__ao_device_check_last(libxl__gc *gc,
libxl__ao_device *device,
     return error;
 }

+/******************************************************************************/
+
+/* Macro for defining the functions that will add a bunch of disks when
+ * inside an async op.
+ *
+ * This macro is added to prevent repetition of code.
+ */
+#define DEFINE_DEVICES_ADD(type)                                              \
+    void libxl__add_##type##s(libxl__egc *egc, libxl__ao *ao, uint32_t domid, \
+                              libxl_domain_config *d_config,                  \
+                              libxl__ao_device **devices,                     \
+                              libxl__device_callback *callback)               \
+    {                                                                         \
+        AO_GC;                                                                \
+        GCNEW_ARRAY(*devices, d_config->num_##type##s);
\
+        libxl__ao_device *aodev = *devices;                                   \
+        int i;                                                                \
+                                                                              \
+        for (i = 0; i < d_config->num_##type##s; i++) {
\
+            libxl__prepare_ao_device(&aodev[i], ao, devices);
\
+            aodev[i].callback = callback;                                     \
+        }                                                                     \
+                                                                              \
+        for (i = 0; i < d_config->num_##type##s; i++) {
\
+            libxl__device_##type##_add(egc, domid,
&d_config->type##s[i],     \
+                                       &aodev[i]);
\
+        }                                                                     \
+    }
+
+DEFINE_DEVICES_ADD(disk)
+
+#undef DEFINE_DEVICES_ADD
+
+/******************************************************************************/
+
 int libxl__device_destroy(libxl__gc *gc, libxl__device *dev)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
@@ -536,6 +571,36 @@ static void device_backend_callback(libxl__egc *egc,
libxl__ev_devstate *ds,
 static void device_backend_cleanup(libxl__gc *gc,
                                    libxl__ao_device *aodev);

+void libxl__initiate_device_add(libxl__egc *egc, libxl__ao_device *aodev)
+{
+    STATE_AO_GC(aodev->ao);
+    char *be_path = libxl__device_backend_path(gc, aodev->dev);
+    char *state_path = libxl__sprintf(gc, "%s/state", be_path);
+    int rc = 0;
+
+    if (aodev->dev->backend_kind == LIBXL__DEVICE_KIND_QDISK) {
+        aodev->callback(egc, aodev);
+        return;
+    }
+
+    libxl__ev_devstate_init(&aodev->ds);
+    rc = libxl__ev_devstate_wait(gc, &aodev->ds,
device_backend_callback,
+                                 state_path, XenbusStateInitWait,
+                                 LIBXL_INIT_TIMEOUT * 1000);
+    if (rc) {
+        LOGE(ERROR, "unable to initialize device %s", be_path);
+        goto out_fail;
+    }
+
+    return;
+
+out_fail:
+    assert(rc);
+    aodev->rc = rc;
+    aodev->callback(egc, aodev);
+    return;
+}
+
 void libxl__initiate_device_remove(libxl__egc *egc,
                                    libxl__ao_device *aodev)
 {
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 99059dc..dbd8431 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -673,6 +673,13 @@ static void spawn_stubdom_pvqemu_cb(libxl__egc *egc,
                                 libxl__dm_spawn_state *stubdom_dmss,
                                 int rc);

+static void spawn_stub_launch_dm(libxl__egc *egc,
+                                 libxl__stub_dm_spawn_state *sdss, int rc);
+
+DEFINE_DEVICES_CALLBACK(spawn_stub_disk_connected,
+                        libxl__stub_dm_spawn_state,
+                        devices, num_devices, spawn_stub_launch_dm)
+
 static void spaw_stubdom_pvqemu_destroy_cb(libxl__egc *egc,
                                            libxl__destroy_domid_state *dis,
                                            int rc);
@@ -681,8 +688,7 @@ void libxl__spawn_stub_dm(libxl__egc *egc,
libxl__stub_dm_spawn_state *sdss)
 {
     STATE_AO_GC(sdss->dm.spawn.ao);
     libxl_ctx *ctx = libxl__gc_owner(gc);
-    int i, num_console = STUBDOM_SPECIAL_CONSOLES, ret;
-    libxl__device_console *console;
+    int ret;
     libxl_device_vfb vfb;
     libxl_device_vkb vkb;
     char **args;
@@ -801,22 +807,52 @@ retry_transaction:
         if (errno == EAGAIN)
             goto retry_transaction;

-    for (i = 0; i < dm_config->num_disks; i++) {
-        ret = libxl_device_disk_add(ctx, dm_domid,
&dm_config->disks[i]);
-        if (ret)
-            goto out_free;
-    }
+    sdss->num_devices = dm_config->num_disks;
+    libxl__add_disks(egc, ao, dm_domid, dm_config, &sdss->devices,
+                     spawn_stub_disk_connected);
+
+    free(args);
+    return;
+
+out_free:
+    free(args);
+out:
+    assert(ret);
+    spawn_stubdom_pvqemu_cb(egc, &sdss->pvqemu, ret);
+}
+
+static void spawn_stub_launch_dm(libxl__egc *egc,
+                                 libxl__stub_dm_spawn_state *sdss, int rc)
+{
+    STATE_AO_GC(sdss->dm.spawn.ao);
+    libxl_ctx *ctx = libxl__gc_owner(gc);
+    int i, num_console = STUBDOM_SPECIAL_CONSOLES, ret = 0;
+    libxl__device_console *console;
+
+    /* convenience aliases */
+    libxl_domain_config *const dm_config = &sdss->dm_config;
+    libxl_domain_config *const guest_config = sdss->dm.guest_config;
+    const int guest_domid = sdss->dm.guest_domid;
+    libxl__domain_build_state *const d_state = sdss->dm.build_state;
+    libxl__domain_build_state *const stubdom_state = &sdss->dm_state;
+    uint32_t dm_domid = sdss->pvqemu.guest_domid;
+
+    if (rc) {
+        LOG(ERROR, "error connecting disk devices");
+        goto out;
+     }
+
     for (i = 0; i < dm_config->num_vifs; i++) {
         ret = libxl_device_nic_add(ctx, dm_domid, &dm_config->vifs[i]);
         if (ret)
-            goto out_free;
+            goto out;
     }
     ret = libxl_device_vfb_add(ctx, dm_domid, &dm_config->vfbs[0]);
     if (ret)
-        goto out_free;
+        goto out;
     ret = libxl_device_vkb_add(ctx, dm_domid, &dm_config->vkbs[0]);
     if (ret)
-        goto out_free;
+        goto out;

     if (guest_config->b_info.u.hvm.serial)
         num_console++;
@@ -824,7 +860,7 @@ retry_transaction:
     console = libxl__calloc(gc, num_console, sizeof(libxl__device_console));
     if (!console) {
         ret = ERROR_NOMEM;
-        goto out_free;
+        goto out;
     }

     for (i = 0; i < num_console; i++) {
@@ -860,7 +896,7 @@ retry_transaction:
         ret = libxl__device_console_add(gc, dm_domid, &console[i],
                         i == STUBDOM_CONSOLE_LOGGING ? stubdom_state : NULL);
         if (ret)
-            goto out_free;
+            goto out;
     }

     sdss->pvqemu.spawn.ao = ao;
@@ -871,11 +907,8 @@ retry_transaction:

     libxl__spawn_local_dm(egc, &sdss->pvqemu);

-    free(args);
     return;

-out_free:
-    free(args);
 out:
     assert(ret);
     spawn_stubdom_pvqemu_cb(egc, &sdss->pvqemu, ret);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 5c15ca5..6df68a6 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -70,6 +70,7 @@
 #include "_libxl_types_internal.h"
 #include "_libxl_types_internal_json.h"

+#define LIBXL_INIT_TIMEOUT 10
 #define LIBXL_DESTROY_TIMEOUT 10
 #define LIBXL_DEVICE_MODEL_START_TIMEOUT 10
 #define LIBXL_XENCONSOLE_LIMIT 1048576
@@ -1844,6 +1845,21 @@ struct libxl__ao_device {
     void *base;
 };

+/* Internal AO operation to connect a disk device, called by
+ * libxl_device_disk_add and libxl__add_disks. This function calls
+ * libxl__initiate_device_add */
+_hidden void libxl__device_disk_add(libxl__egc *egc, uint32_t domid,
+                                    libxl_device_disk *disk,
+                                    libxl__ao_device *aodev);
+
+/* Arranges that dev will be added to the guest, and the
+ * hotplug scripts will be executed (if necessary). When
+ * this is done (or an error happens), the callback in
+ * aodev->callback will be called.
+ */
+_hidden void libxl__initiate_device_add(libxl__egc*, libxl__ao_device *aodev);
+
+
 /* Arranges that dev will be removed to the guest, and the
  * hotplug scripts will be executed (if necessary). When
  * this is done (or an error happens), the callback in
@@ -1936,6 +1952,36 @@ _hidden void libxl__destroy_domid(libxl__egc *egc,
 _hidden void libxl__devices_destroy(libxl__egc *egc,
                                     libxl__devices_remove_state *drs);

+/* Helper function to add a bunch of disks. This should be used when
+ * the caller is inside an async op. "devices" will be prepared by
this
+ * function, so there''s no need to call _prepare before calling this
+ * function.
+ *
+ * The "callback" will be called for each device, and the user is
responsible
+ * for calling libxl__ao_device_check_last on the callback.
+ */
+void libxl__add_disks(libxl__egc *egc, libxl__ao *ao, uint32_t domid,
+                      libxl_domain_config *d_config,
+                      libxl__ao_device **devices,
+                      libxl__device_callback *callback);
+
+/* Macro to define callbacks of libxl__add_*, checks if device is last
+ * and calls the function passed as a parameter to this macro with the
+ * following syntax; func(libxl__egc *, parent_type *, int rc) */
+#define DEFINE_DEVICES_CALLBACK(callback_name, parent_type, array_name,       \
+                                array_size_name, func_to_call)                \
+    static void callback_name(libxl__egc *egc, libxl__ao_device *aodev)       \
+    {                                                                         \
+        STATE_AO_GC(aodev->ao);
\
+        parent_type *p = CONTAINER_OF(aodev->base, *p, array_name);
\
+        int rc;                                                               \
+                                                                              \
+        rc = libxl__ao_device_check_last(gc, aodev, p->array_name,
\
+                                         p->array_size_name);
\
+        if (rc > 0) return;
\
+        func_to_call(egc, p, rc);                                             \
+    }
+
 /*----- device model creation -----*/

 /* First layer; wraps libxl__spawn_spawn. */
@@ -1970,6 +2016,9 @@ typedef struct {
     libxl__domain_build_state dm_state;
     libxl__dm_spawn_state pvqemu;
     libxl__destroy_domid_state dis;
+    /* used to store the state of devices being connected */
+    libxl__ao_device *devices;
+    int num_devices;
 } libxl__stub_dm_spawn_state;

 _hidden void libxl__spawn_stub_dm(libxl__egc *egc,
libxl__stub_dm_spawn_state*);
@@ -1998,6 +2047,9 @@ struct libxl__domain_create_state {
          * for the non-stubdom device model. */
     /* necessary if the domain creation failed and we have to destroy it */
     libxl__domain_destroy_state dds;
+    /* used to store the state of devices being connected */
+    libxl__ao_device *devices;
+    int num_devices;
 };

 /*
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 3220e89..a7fa0b9 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -5343,7 +5343,7 @@ int main_blockattach(int argc, char **argv)
         return 0;
     }

-    if (libxl_device_disk_add(ctx, fe_domid, &disk)) {
+    if (libxl_device_disk_add(ctx, fe_domid, &disk, 0)) {
         fprintf(stderr, "libxl_device_disk_add failed.\n");
     }
     return 0;
--
1.7.7.5 (Apple Git-26)