- We need to have good error reporting in the callbacks in
VMStateDescription struct. Specifically pre_save, pre_load
and post_load callbacks.
- It is not possible to change these functions everywhere in one
patch, therefore, we introduce a duplicate set of callbacks
with Error object passed to them.
- So, in this commit, we implement 'errp' variants of these callbacks,
introducing an explicit Error object parameter.
- This is a functional step towards transitioning the entire codebase
to the new error-parameterized functions.
- Deliberately called in mutual exclusion from their counterparts,
to prevent conflicts during the transition.
- New impls should preferentally use 'errp' variants of
these methods, and existing impls incrementally converted.
The variants without 'errp' are intended to be removed
once all usage is converted.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Arun Menon <armenon@redhat.com>
---
docs/devel/migration/main.rst | 19 +++++++++++++++++++
include/migration/vmstate.h | 14 ++++++++++++++
migration/vmstate.c | 31 ++++++++++++++++++++++++++++---
3 files changed, 61 insertions(+), 3 deletions(-)
diff --git a/docs/devel/migration/main.rst b/docs/devel/migration/main.rst
index a39fec2e21c26c4315c0cf13b105176d70679d4d..93620102ae875e7477af2e26eeffe636ca0cdbca 100644
--- a/docs/devel/migration/main.rst
+++ b/docs/devel/migration/main.rst
@@ -444,6 +444,25 @@ The functions to do that are inside a vmstate definition, and are called:
This function is called after we save the state of one device
(even upon failure, unless the call to pre_save returned an error).
+Following are the errp variants of these functions.
+
+- ``int (*pre_load_errp)(void *opaque, Error **errp);``
+
+ This function is called before we load the state of one device.
+
+- ``int (*post_load_errp)(void *opaque, int version_id, Error **errp);``
+
+ This function is called after we load the state of one device.
+
+- ``int (*pre_save_errp)(void *opaque, Error **errp);``
+
+ This function is called before we save the state of one device.
+
+New impls should preferentally use 'errp' variants of these
+methods and existing impls incrementally converted.
+The variants without 'errp' are intended to be removed
+once all usage is converted.
+
Example: You can look at hpet.c, that uses the first three functions
to massage the state that is transferred.
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index c1d8e5b7a7d9d544fc8ce181372660f5538ef66b..647d7a35ce5f2c8b8ca5fdb15b54c10a0896cea8 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -200,14 +200,28 @@ struct VMStateDescription {
* exclusive. For this reason, also early_setup VMSDs are migrated in a
* QEMU_VM_SECTION_FULL section, while save_setup() data is migrated in
* a QEMU_VM_SECTION_START section.
+ *
+ * There are duplicate impls of the post/pre save/load hooks.
+ * New impls should preferentally use 'errp' variants of these
+ * methods and existing impls incrementally converted.
+ * The variants without 'errp' are intended to be removed
+ * once all usage is converted.
+ *
+ * For the errp variants,
+ * Returns: 0 on success,
+ * <0 on error where -value is an error number from errno.h
*/
+
bool early_setup;
int version_id;
int minimum_version_id;
MigrationPriority priority;
int (*pre_load)(void *opaque);
+ int (*pre_load_errp)(void *opaque, Error **errp);
int (*post_load)(void *opaque, int version_id);
+ int (*post_load_errp)(void *opaque, int version_id, Error **errp);
int (*pre_save)(void *opaque);
+ int (*pre_save_errp)(void *opaque, Error **errp);
void (*cleanup_save)(void *opaque);
bool (*needed)(void *opaque);
bool (*dev_unplug_pending)(void *opaque);
diff --git a/migration/vmstate.c b/migration/vmstate.c
index a7562a5cfd8627e20c90e286e35c5e3429c48150..86293593e0fbb8409409b22d3f0653327d727c32 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -134,6 +134,7 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, int version_id, Error **errp)
{
+ ERRP_GUARD();
const VMStateField *field = vmsd->fields;
int ret = 0;
@@ -152,7 +153,16 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
return -EINVAL;
}
- if (vmsd->pre_load) {
+ if (vmsd->pre_load_errp) {
+ ret = vmsd->pre_load_errp(opaque, errp);
+ if (ret < 0) {
+ error_prepend(errp, "pre load hook failed for: '%s', "
+ "version_id: %d, minimum version_id: %d, "
+ "ret: %d: ", vmsd->name, vmsd->version_id,
+ vmsd->minimum_version_id, ret);
+ return ret;
+ }
+ } else if (vmsd->pre_load) {
ret = vmsd->pre_load(opaque);
if (ret) {
error_setg(errp, "pre load hook failed for: '%s', "
@@ -245,7 +255,14 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
qemu_file_set_error(f, ret);
return ret;
}
- if (vmsd->post_load) {
+ if (vmsd->post_load_errp) {
+ ret = vmsd->post_load_errp(opaque, version_id, errp);
+ if (ret < 0) {
+ error_prepend(errp, "post load hook failed for: %s, version_id: "
+ "%d, minimum_version: %d, ret: %d: ", vmsd->name,
+ vmsd->version_id, vmsd->minimum_version_id, ret);
+ }
+ } else if (vmsd->post_load) {
ret = vmsd->post_load(opaque, version_id);
if (ret < 0) {
error_setg(errp,
@@ -414,12 +431,20 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
{
+ ERRP_GUARD();
int ret = 0;
const VMStateField *field = vmsd->fields;
trace_vmstate_save_state_top(vmsd->name);
- if (vmsd->pre_save) {
+ if (vmsd->pre_save_errp) {
+ ret = vmsd->pre_save_errp(opaque, errp);
+ trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
+ if (ret < 0) {
+ error_prepend(errp, "pre-save for %s failed, ret: %d: ",
+ vmsd->name, ret);
+ }
+ } else if (vmsd->pre_save) {
ret = vmsd->pre_save(opaque);
trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
if (ret) {
--
2.51.0