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Re: [Qemu-devel] [PATCH 6/6] migration: Pass Error ** argument to {save,
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH 6/6] migration: Pass Error ** argument to {save, load}_vmstate |
Date: |
Fri, 28 Apr 2017 17:19:03 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) |
"Dr. David Alan Gilbert" <address@hidden> writes:
> * Juan Quintela (address@hidden) wrote:
>> This way we use the "normal" way of printing errors for hmp commands.
>>
>> --
>> Paolo suggestion
>>
>> Signed-off-by: Juan Quintela <address@hidden>
>
> <snip>
>
>> +int save_vmstate(const char *name, Error **errp)
>> {
>> BlockDriverState *bs, *bs1;
>> QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
>> @@ -2076,29 +2076,27 @@ int save_vmstate(const char *name)
>> uint64_t vm_state_size;
>> qemu_timeval tv;
>> struct tm tm;
>> - Error *local_err = NULL;
>> AioContext *aio_context;
>>
>> if (!bdrv_all_can_snapshot(&bs)) {
>> - error_report("Device '%s' is writable but does not support
>> snapshots",
>> - bdrv_get_device_name(bs));
>> + error_setg(errp, "Device '%s' is writable but does not support "
>> + "snapshots", bdrv_get_device_name(bs));
>> return ret;
>> }
>>
>> /* Delete old snapshots of the same name */
>> if (name) {
>> - ret = bdrv_all_delete_snapshot(name, &bs1, &local_err);
>> + ret = bdrv_all_delete_snapshot(name, &bs1, errp);
>> if (ret < 0) {
>> - error_reportf_err(local_err,
>> - "Error while deleting snapshot on device
>> '%s': ",
>> - bdrv_get_device_name(bs1));
>> + error_prepend(errp, "Error while deleting snapshot on device "
>> + "'%s': ", bdrv_get_device_name(bs1));
>
> I thought the rule was that you had to use a local_err and use
> error_propagate?
> (I hate that rule)
Quote qapi/error.h:
* Receive an error and pass it on to the caller:
* Error *err = NULL;
* foo(arg, &err);
* if (err) {
* handle the error...
* error_propagate(errp, err);
* }
* where Error **errp is a parameter, by convention the last one.
*
* Do *not* "optimize" this to
* foo(arg, errp);
* if (*errp) { // WRONG!
* handle the error...
* }
* because errp may be NULL!
*
* But when all you do with the error is pass it on, please use
* foo(arg, errp);
* for readability.
Neglects to mention you can error_prepend() and still avoid
error_propagate(), but the comment is long enough as it is.
>> return ret;
>> }
>> }
>>
>> bs = bdrv_all_find_vmstate_bs();
>> if (bs == NULL) {
>> - error_report("No block device can accept snapshots");
>> + error_setg(errp, "No block device can accept snapshots");
>> return ret;
>> }
>> aio_context = bdrv_get_aio_context(bs);
>> @@ -2107,7 +2105,7 @@ int save_vmstate(const char *name)
>>
>> ret = global_state_store();
>> if (ret) {
>> - error_report("Error saving global state");
>> + error_setg(errp, "Error saving global state");
>> return ret;
>> }
>> vm_stop(RUN_STATE_SAVE_VM);
>> @@ -2139,21 +2137,20 @@ int save_vmstate(const char *name)
>> /* save the VM state */
>> f = qemu_fopen_bdrv(bs, 1);
>> if (!f) {
>> - error_report("Could not open VM state file");
>> + error_setg(errp, "Could not open VM state file");
>> goto the_end;
>> }
>> - ret = qemu_savevm_state(f, &local_err);
>> + ret = qemu_savevm_state(f, errp);
>> vm_state_size = qemu_ftell(f);
>> qemu_fclose(f);
>> if (ret < 0) {
>> - error_report_err(local_err);
>> goto the_end;
>> }
>>
>> ret = bdrv_all_create_snapshot(sn, bs, vm_state_size, &bs);
>> if (ret < 0) {
>> - error_report("Error while creating snapshot on '%s'",
>> - bdrv_get_device_name(bs));
>> + error_setg(errp, "Error while creating snapshot on '%s'",
>> + bdrv_get_device_name(bs));
>> goto the_end;
>> }
>>
>> @@ -2226,7 +2223,7 @@ void qmp_xen_load_devices_state(const char *filename,
>> Error **errp)
>> migration_incoming_state_destroy();
>> }
>>
>> -int load_vmstate(const char *name)
>> +int load_vmstate(const char *name, Error **errp)
>> {
>> BlockDriverState *bs, *bs_vm_state;
>> QEMUSnapshotInfo sn;
>> @@ -2236,20 +2233,22 @@ int load_vmstate(const char *name)
>> MigrationIncomingState *mis = migration_incoming_get_current();
>>
>> if (!bdrv_all_can_snapshot(&bs)) {
>> - error_report("Device '%s' is writable but does not support
>> snapshots",
>> - bdrv_get_device_name(bs));
>> + error_setg(errp,
>> + "Device '%s' is writable but does not support snapshots",
>> + bdrv_get_device_name(bs));
>> return -ENOTSUP;
>> }
>> ret = bdrv_all_find_snapshot(name, &bs);
>> if (ret < 0) {
>> - error_report("Device '%s' does not have the requested snapshot
>> '%s'",
>> - bdrv_get_device_name(bs), name);
>> + error_setg(errp,
>> + "Device '%s' does not have the requested snapshot '%s'",
>> + bdrv_get_device_name(bs), name);
>> return ret;
>> }
>>
>> bs_vm_state = bdrv_all_find_vmstate_bs();
>> if (!bs_vm_state) {
>> - error_report("No block device supports snapshots");
>> + error_setg(errp, "No block device supports snapshots");
>> return -ENOTSUP;
>> }
>> aio_context = bdrv_get_aio_context(bs_vm_state);
>> @@ -2261,8 +2260,8 @@ int load_vmstate(const char *name)
>> if (ret < 0) {
>> return ret;
>> } else if (sn.vm_state_size == 0) {
>> - error_report("This is a disk-only snapshot. Revert to it offline "
>> - "using qemu-img.");
>> + error_setg(errp, "This is a disk-only snapshot. Revert to it "
>> + " offline using qemu-img");
>> return -EINVAL;
>> }
>>
>> @@ -2271,7 +2270,7 @@ int load_vmstate(const char *name)
>>
>> ret = bdrv_all_goto_snapshot(name, &bs);
>> if (ret < 0) {
>> - error_report("Error %d while activating snapshot '%s' on '%s'",
>> + error_setg(errp, "Error %d while activating snapshot '%s' on '%s'",
>> ret, name, bdrv_get_device_name(bs));
>> return ret;
>> }
>> @@ -2279,7 +2278,7 @@ int load_vmstate(const char *name)
>> /* restore the VM state */
>> f = qemu_fopen_bdrv(bs_vm_state, 0);
>> if (!f) {
>> - error_report("Could not open VM state file");
>> + error_setg(errp, "Could not open VM state file");
>> return -EINVAL;
>> }
>>
>> @@ -2293,7 +2292,7 @@ int load_vmstate(const char *name)
>>
>> migration_incoming_state_destroy();
>> if (ret < 0) {
>> - error_report("Error %d while loading VM state", ret);
>> + error_setg(errp, "Error %d while loading VM state", ret);
>> return ret;
>> }
>>
>> diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
>> index 8cced46..fdc4353 100644
>> --- a/replay/replay-snapshot.c
>> +++ b/replay/replay-snapshot.c
>> @@ -62,14 +62,16 @@ void replay_vmstate_register(void)
>>
>> void replay_vmstate_init(void)
>> {
>> + Error *err = NULL;
>> +
>> if (replay_snapshot) {
>> if (replay_mode == REPLAY_MODE_RECORD) {
>> - if (save_vmstate(replay_snapshot) != 0) {
>> + if (save_vmstate(replay_snapshot, &err) != 0) {
>> error_report("Could not create snapshot for icount record");
>> exit(1);
>> }
>> } else if (replay_mode == REPLAY_MODE_PLAY) {
>> - if (load_vmstate(replay_snapshot) != 0) {
>> + if (load_vmstate(replay_snapshot, &err) != 0) {
>> error_report("Could not load snapshot for icount replay");
>> exit(1);
>> }
>
> How do either of the contents of the 'err' get reported - they're not
> printed at all are they?
> (I don't like error_abort, I'd rather see the other message as well).
I guess you mean &error_fatal.
Consider error_report_err().
>
> Dave
>
>> diff --git a/vl.c b/vl.c
>> index 0b4ed52..8b3ec2e 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -4681,7 +4681,9 @@ int main(int argc, char **argv, char **envp)
>> if (replay_mode != REPLAY_MODE_NONE) {
>> replay_vmstate_init();
>> } else if (loadvm) {
>> - if (load_vmstate(loadvm) < 0) {
>> + Error *local_err = NULL;
>> + if (load_vmstate(loadvm, &local_err) < 0) {
>> + error_report_err(local_err);
>> autostart = 0;
>> }
>> }
>> --
>> 2.9.3
>>
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
Re: [Qemu-devel] [PATCH 0/6] Move snapshots commands to hmp, Dr. David Alan Gilbert, 2017/04/28