Re: [Qemu-devel] [PATCH for-2.9 V2 2/3] Add a new qmp command to start/stop replication

[Eric Blake]

On 12/08/2016 01:55 AM, Zhang Chen wrote:
> We can call this qmp command to start/stop replication outside of qemu.
> Like Xen colo need this function.
> 
> Signed-off-by: Zhang Chen <address@hidden>
> ---
>  docs/qmp-commands.txt | 17 +++++++++++++++++
>  migration/colo.c      | 22 ++++++++++++++++++++++
>  qapi-schema.json      | 19 +++++++++++++++++++
>  3 files changed, 58 insertions(+)
> 
> diff --git a/docs/qmp-commands.txt b/docs/qmp-commands.txt
> index abf210a..f7bae0d 100644
> --- a/docs/qmp-commands.txt
> +++ b/docs/qmp-commands.txt
> @@ -432,6 +432,23 @@ Example:
>       "arguments": { "enable": true } }
>  <- { "return": {} }
>  
> +xen-set-replication
> +-------

Much of this file tries to match the ----- divider lines to the length
of the line above it (you're short by the length of '-replication')

> +
> +Enable or disable replication.
> +
> +Arguments:
> +
> +- "enable": Enable it or disable it.
> +- "primary": True for primary or false for secondary

We aren't very consistent on whether to end in '.'

> +- "failover": Enable to do failover when stoping replcation

"failover": Enable failover when stopping replication (optional, default
false)


> +void qmp_xen_set_replication(bool enable, bool primary,
> +                             bool has_failover, bool failover,
> +                             Error **errp)
> +{
> +    ReplicationMode mode = primary ?
> +                           REPLICATION_MODE_PRIMARY :
> +                           REPLICATION_MODE_SECONDARY;
> +
> +    if (has_failover && enable) {
> +        error_setg(errp, "Parameter 'failover' is only for"
> +                   " stopping replication");

At this point, errp is set, but you fall through...

> +    }
> +
> +    if (enable) {
> +        replication_start_all(mode, errp);

and could abort if something else also tries to set errp.  Simplest is
to add a return; statement after error_setg().

> +    } else {
> +        replication_stop_all(failover, failover ? NULL : errp);
> +    }
> +}
> +
>  static void colo_send_message(QEMUFile *f, COLOMessage msg,
>                                Error **errp)
>  {
> diff --git a/qapi-schema.json b/qapi-schema.json
> index f3e9bfc..f67b0a3 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -4676,6 +4676,25 @@
>  { 'command': 'xen-load-devices-state', 'data': {'filename': 'str'} }
>  
>  ##
> +# @xen-set-replication
> +#
> +# Enable or disable replication
> +#
> +# @enable: true to enable, false to disable.
> +#
> +# @primary: true for primary or false for secondary
> +#
> +# @failover: #optional true to do failover, false to stop.
> +#            default value is false.

May want to additionally document that 'failover' cannot be specified if
'enable' is true.

> +#
> +# Returns: nothing
> +#
> +# Since: 2.9
> +##
> +{ 'command': 'xen-set-replication',
> +  'data': { 'enable': 'bool', 'primary': 'bool', '*failover' : 'bool' } }
> +
> +##
>  # @GICCapability:
>  #
>  # The struct describes capability for a specific GIC (Generic
> 

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

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