Re: [Qemu-devel] [PATCH] migration: Fix possible bug for migrate cancel

[Eric Blake <eblake@redhat.com>]

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On 03/24/2014 07:04 AM, arei.gonglei@huawei.com wrote:
> From: zengjunliang <zengjunliang@huawei.com>
> 
> Return error for migrate cancel, when migration status is not
> MIG_STATE_SETUP or MIG_STATE_ACTIVE. Thus, libvirt can can
> perceive the operation fails.
> 
> Signed-off-by: zengjunliang <zengjunliang@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
>  include/qapi/qmp/qerror.h | 3 +++
>  migration.c               | 5 +++--
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/include/qapi/qmp/qerror.h b/include/qapi/qmp/qerror.h
> index da75abf..b13e3e0 100644
> --- a/include/qapi/qmp/qerror.h
> +++ b/include/qapi/qmp/qerror.h
> @@ -164,6 +164,9 @@ void qerror_report_err(Error *err);
>  #define QERR_MIGRATION_ACTIVE \
>      ERROR_CLASS_GENERIC_ERROR, "There's a migration process in progress"
>  
> +#define QERR_MIGRATION_COMPLETED \

New code should NOT be adding macros in qerror.h, but just directly
report the error.

> +    ERROR_CLASS_GENERIC_ERROR, "There's no migration process in progress"

You use a generic error both for migration active and for no migration
in progress.  The error API documents that clients (such as libvirt)
must NOT parse the human-readable string.  If libvirt is actually going
to behave differently for this particular error, that argues that it may
need a different error category than GENERIC_ERROR.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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