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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 6/9] libxl_disk: Cut libxl_cdrom_insert into steps ..
.. and use a new "slow" lock to avoid holding the userdata lock across
several functions.
This patch cuts libxl_cdrom_insert into different step/function but
there are still called synchronously. (Taking the ev_lock is the only
step that might be asynchronous.) A later patch will call them
asynchronously when QMP is involved.
Thee userdata lock (json_lock) use to protect against concurrent change
of cdrom is replaced by an ev_lock which can be held across different
CTX_LOCK sections. The json_lock is still used when reading/modifying
the domain userdata (mandatory) and update xenstore (mostly because
it's updated as the same time as the userdata).
Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
Notes:
v2:
- rewrite patch description
- rework use of the new lock
tools/libxl/libxl_disk.c | 196 +++++++++++++++++++++++++++++++--------
1 file changed, 155 insertions(+), 41 deletions(-)
diff --git a/tools/libxl/libxl_disk.c b/tools/libxl/libxl_disk.c
index 45bf555061..5f13a622f9 100644
--- a/tools/libxl/libxl_disk.c
+++ b/tools/libxl/libxl_disk.c
@@ -642,24 +642,43 @@ int libxl_device_disk_getinfo(libxl_ctx *ctx, uint32_t
domid,
return rc;
}
+typedef struct {
+ libxl__ao *ao;
+ libxl_domid domid;
+ libxl_device_disk *disk;
+ libxl_device_disk disk_saved;
+ libxl__ev_lock qmp_lock;
+ int dm_ver;
+} libxl__cdrom_insert_state;
+
+static void cdrom_insert_lock_acquired(libxl__egc *, libxl__ev_lock *,
+ int rc);
+static void cdrom_insert_ejected(libxl__egc *egc,
+ libxl__cdrom_insert_state *cis);
+static void cdrom_insert_inserted(libxl__egc *egc,
+ libxl__cdrom_insert_state *cis);
+static void cdrom_insert_done(libxl__egc *egc,
+ libxl__cdrom_insert_state *cis,
+ int rc);
+
int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid, libxl_device_disk *disk,
const libxl_asyncop_how *ao_how)
{
AO_CREATE(ctx, domid, ao_how);
int num = 0, i;
- libxl_device_disk *disks = NULL, disk_saved;
- libxl_domain_config d_config;
- int rc, dm_ver;
- libxl__device device;
- const char *be_path, *libxl_path;
- char * tmp;
- libxl__domain_userdata_lock *lock = NULL;
- xs_transaction_t t = XBT_NULL;
- flexarray_t *insert = NULL, *empty = NULL;
-
- libxl_domain_config_init(&d_config);
- libxl_device_disk_init(&disk_saved);
- libxl_device_disk_copy(ctx, &disk_saved, disk);
+ libxl_device_disk *disks = NULL;
+ int rc;
+ libxl__cdrom_insert_state *cis;
+
+ GCNEW(cis);
+ cis->ao = ao;
+ cis->domid = domid;
+ cis->disk = disk;
+ libxl_device_disk_init(&cis->disk_saved);
+ libxl_device_disk_copy(ctx, &cis->disk_saved, disk);
+ libxl__ev_lock_init(&cis->qmp_lock);
+ cis->qmp_lock.ao = ao;
+ cis->qmp_lock.domid = domid;
libxl_domain_type type = libxl__domain_type(gc, domid);
if (type == LIBXL_DOMAIN_TYPE_INVALID) {
@@ -678,8 +697,8 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *disk,
goto out;
}
- dm_ver = libxl__device_model_version_running(gc, domid);
- if (dm_ver == -1) {
+ cis->dm_ver = libxl__device_model_version_running(gc, domid);
+ if (cis->dm_ver == -1) {
LOGD(ERROR, domid, "Cannot determine device model version");
rc = ERROR_FAIL;
goto out;
@@ -708,40 +727,82 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *disk,
disk->format = LIBXL_DISK_FORMAT_EMPTY;
}
- rc = libxl__device_from_disk(gc, domid, disk, &device);
- if (rc) goto out;
+out:
+ libxl__device_list_free(&libxl__disk_devtype, disks, num);
+ if (rc) {
+ cdrom_insert_done(egc, cis, rc); /* must be last */
+ } else {
+ cis->qmp_lock.callback = cdrom_insert_lock_acquired;
+ libxl__ev_lock_get(egc, &cis->qmp_lock); /* must be last */
+ }
+ return AO_INPROGRESS;
+}
- be_path = libxl__device_backend_path(gc, &device);
- libxl_path = libxl__device_libxl_path(gc, &device);
+static void cdrom_insert_lock_acquired(libxl__egc *egc,
+ libxl__ev_lock *lock,
+ int rc)
+{
+ libxl__cdrom_insert_state *cis = CONTAINER_OF(lock, *cis, qmp_lock);
+ STATE_AO_GC(cis->ao);
- /* Note: CTX lock is already held at this point so lock hierarchy
- * is maintained.
- */
- lock = libxl__lock_domain_userdata(gc, domid);
- if (!lock) {
- rc = ERROR_LOCK_FAIL;
- goto out;
- }
+ if (rc) goto out;
/* We need to eject the original image first. This is implemented
* by inserting empty media. JSON is not updated.
*/
- if (dm_ver == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
+ if (cis->dm_ver == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
libxl_device_disk disk_empty;
libxl_device_disk_init(&disk_empty);
disk_empty.format = LIBXL_DISK_FORMAT_EMPTY;
- disk_empty.vdev = libxl__strdup(NOGC, disk->vdev);
+ disk_empty.vdev = libxl__strdup(NOGC, cis->disk->vdev);
disk_empty.pdev_path = libxl__strdup(NOGC, "");
disk_empty.is_cdrom = 1;
- libxl__device_disk_setdefault(gc, domid, &disk_empty, false);
+ libxl__device_disk_setdefault(gc, cis->domid, &disk_empty, false);
- rc = libxl__qmp_insert_cdrom(gc, domid, &disk_empty);
+ rc = libxl__qmp_insert_cdrom(gc, cis->domid, &disk_empty);
libxl_device_disk_dispose(&disk_empty);
if (rc) goto out;
}
+ cdrom_insert_ejected(egc, cis); /* must be last */
+ return;
+
+out:
+ cdrom_insert_done(egc, cis, rc); /* must be last */
+}
+
+static void cdrom_insert_ejected(libxl__egc *egc,
+ libxl__cdrom_insert_state *cis)
+{
+ EGC_GC;
+ int rc;
+ libxl__domain_userdata_lock *data_lock = NULL;
+ libxl__device device;
+ const char *be_path, *libxl_path;
+ flexarray_t *empty = NULL;
+ xs_transaction_t t = XBT_NULL;
+ char *tmp;
+ libxl_domain_config d_config;
+
+ /* convenience aliases */
+ libxl_domid domid = cis->domid;
+ libxl_device_disk *disk = cis->disk;
+
+ libxl_domain_config_init(&d_config);
+
+ rc = libxl__device_from_disk(gc, domid, disk, &device);
+ if (rc) goto out;
+ be_path = libxl__device_backend_path(gc, &device);
+ libxl_path = libxl__device_libxl_path(gc, &device);
+
+ data_lock = libxl__lock_domain_userdata(gc, domid);
+ if (!data_lock) {
+ rc = ERROR_LOCK_FAIL;
+ goto out;
+ }
+
empty = flexarray_make(gc, 4, 1);
flexarray_append_pair(empty, "type",
libxl__device_disk_string_of_backend(disk->backend));
@@ -780,16 +841,66 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *disk,
rc = libxl__get_domain_configuration(gc, domid, &d_config);
if (rc) goto out;
- device_add_domain_config(gc, &d_config, &libxl__disk_devtype, &disk_saved);
+ device_add_domain_config(gc, &d_config, &libxl__disk_devtype,
+ &cis->disk_saved);
rc = libxl__dm_check_start(gc, &d_config, domid);
if (rc) goto out;
- if (dm_ver == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
+ if (cis->dm_ver == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
rc = libxl__qmp_insert_cdrom(gc, domid, disk);
if (rc) goto out;
}
+ rc = 0;
+
+out:
+ libxl__xs_transaction_abort(gc, &t);
+ libxl_domain_config_dispose(&d_config);
+ if (data_lock) libxl__unlock_domain_userdata(data_lock);
+ if (rc) {
+ cdrom_insert_done(egc, cis, rc); /* must be last */
+ } else {
+ cdrom_insert_inserted(egc, cis); /* must be last */
+ }
+}
+
+static void cdrom_insert_inserted(libxl__egc *egc,
+ libxl__cdrom_insert_state *cis)
+{
+ EGC_GC;
+ int rc;
+ libxl__domain_userdata_lock *data_lock = NULL;
+ libxl_domain_config d_config;
+ flexarray_t *insert = NULL;
+ xs_transaction_t t = XBT_NULL;
+ libxl__device device;
+ const char *be_path, *libxl_path;
+ char *tmp;
+
+ /* convenience aliases */
+ libxl_domid domid = cis->domid;
+ libxl_device_disk *disk = cis->disk;
+
+ libxl_domain_config_init(&d_config);
+
+ rc = libxl__device_from_disk(gc, domid, disk, &device);
+ if (rc) goto out;
+ be_path = libxl__device_backend_path(gc, &device);
+ libxl_path = libxl__device_libxl_path(gc, &device);
+
+ data_lock = libxl__lock_domain_userdata(gc, domid);
+ if (!data_lock) {
+ rc = ERROR_LOCK_FAIL;
+ goto out;
+ }
+
+ rc = libxl__get_domain_configuration(gc, domid, &d_config);
+ if (rc) goto out;
+
+ device_add_domain_config(gc, &d_config, &libxl__disk_devtype,
+ &cis->disk_saved);
+
insert = flexarray_make(gc, 4, 1);
flexarray_append_pair(insert, "type",
libxl__device_disk_string_of_backend(disk->backend));
@@ -830,21 +941,24 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid,
libxl_device_disk *disk,
if (rc < 0) goto out;
}
- /* success, no actual async */
- libxl__ao_complete(egc, ao, 0);
-
rc = 0;
out:
libxl__xs_transaction_abort(gc, &t);
- libxl__device_list_free(&libxl__disk_devtype, disks, num);
- libxl_device_disk_dispose(&disk_saved);
libxl_domain_config_dispose(&d_config);
+ if (data_lock) libxl__unlock_domain_userdata(data_lock);
+ cdrom_insert_done(egc, cis, rc); /* must be last */
+}
- if (lock) libxl__unlock_domain_userdata(lock);
+static void cdrom_insert_done(libxl__egc *egc,
+ libxl__cdrom_insert_state *cis,
+ int rc)
+{
+ EGC_GC;
- if (rc) return AO_CREATE_FAIL(rc);
- return AO_INPROGRESS;
+ libxl__ev_unlock(gc, &cis->qmp_lock);
+ libxl_device_disk_dispose(&cis->disk_saved);
+ libxl__ao_complete(egc, cis->ao, rc);
}
/* libxl__alloc_vdev only works on the local domain, that is the domain
--
Anthony PERARD
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