[libvirt PATCH v3 2/4] qemu_monitor: add support for get qemu migration blockers

[Jiri Denemark]

On Wed, Jul 20, 2022 at 14:15:56 +0200, Eugenio Pérez wrote:
> since qemu 6.0, if migration is blocked for some reason, 'query-migrate'
> will return an array of error strings describing the migration blockers.
> This can be used to check whether there are any devices blocking
> migration, etc.
> 
> Enable qemu monitor to send this query.  This will allow
> qemuMigrationSrcIsAllowed to dynamically ask for migration blockers,
> reducing duplication.
> 
> Signed-off-by: Eugenio Pérez <eperezma at redhat.com>
> ---
> v3:
> * Squash some patches
> * Return ok in qemuMonitorJSONGetMigrationBlockers is there are no
>   blockers.
> * Move note to function doc.
> ---
>  src/qemu/qemu_monitor.c      | 11 +++++++++
>  src/qemu/qemu_monitor.h      |  4 ++++
>  src/qemu/qemu_monitor_json.c | 43 ++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_monitor_json.h |  3 +++
>  4 files changed, 61 insertions(+)
> 
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index 109107eaae..e0939beecd 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -4486,3 +4486,14 @@ qemuMonitorMigrateRecover(qemuMonitor *mon,
>  
>      return qemuMonitorJSONMigrateRecover(mon, uri);
>  }
> +
> +int
> +qemuMonitorGetMigrationBlockers(qemuMonitor *mon,
> +                                char ***blockers)
> +{
> +    VIR_DEBUG("blockers=%p", blockers);
> +
> +    QEMU_CHECK_MONITOR(mon);
> +
> +    return qemuMonitorJSONGetMigrationBlockers(mon, blockers);
> +}
> diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
> index cc1a0bc8c9..b82f198285 100644
> --- a/src/qemu/qemu_monitor.h
> +++ b/src/qemu/qemu_monitor.h
> @@ -1543,3 +1543,7 @@ qemuMonitorChangeMemoryRequestedSize(qemuMonitor *mon,
>  int
>  qemuMonitorMigrateRecover(qemuMonitor *mon,
>                            const char *uri);
> +
> +int
> +qemuMonitorGetMigrationBlockers(qemuMonitor *mon,
> +                                char ***blockers);
> diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> index 5e4a86e5ad..6d15a458a3 100644
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -3338,6 +3338,49 @@ int qemuMonitorJSONMigrate(qemuMonitor *mon,
>      return 0;
>  }
>  
> +/*
> + * Get the exposed migration blockers.
> + *
> + * This function assume qemu has the capability of request them.
> + *
> + * It returns a NULL terminated array on blockers if there are any, or it set
> + * it to NULL otherwise.
> + */
> +int qemuMonitorJSONGetMigrationBlockers(qemuMonitor *mon,

I'm sorry for not noticing this in v2, but the return type should be on
a separate line (yeah, I know the three functions around the place you
put yours do not follow this).

I can change it before pushing to avoid trivial v4 if you don't mind.

With the change
Reviewed-by: Jiri Denemark <jdenemar at redhat.com>