Re: [Qemu-devel] [PATCH 1/5] migrate: add migration blockers

[Anthony Liguori <anthony@codemonkey.ws>]

On 11/14/2011 03:09 PM, Anthony Liguori wrote:
> This lets different subsystems register an Error that is thrown whenever
> migration is attempted.  This works nicely because it gracefully supports
> things like hotplug.
>
> Right now, if multiple errors are registered, only one of them is reported.
> I expect that for 1.1, we'll extend query-migrate to return all of the reasons
> why migration is disabled at any given point in time.
>
> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>

Applied.

Regards,

Anthony Liguori

> ---
>   migration.c |   18 ++++++++++++++++++
>   migration.h |   15 +++++++++++++++
>   2 files changed, 33 insertions(+), 0 deletions(-)
>
> diff --git a/migration.c b/migration.c
> index 41c3c24..6764d3a 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -398,6 +398,18 @@ static MigrationState *migrate_init(Monitor *mon, int detach, int blk, int inc)
>       return s;
>   }
>
> +static GSList *migration_blockers;
> +
> +void migrate_add_blocker(Error *reason)
> +{
> +    migration_blockers = g_slist_prepend(migration_blockers, reason);
> +}
> +
> +void migrate_del_blocker(Error *reason)
> +{
> +    migration_blockers = g_slist_remove(migration_blockers, reason);
> +}
> +
>   int do_migrate(Monitor *mon, const QDict *qdict, QObject **ret_data)
>   {
>       MigrationState *s = migrate_get_current();
> @@ -417,6 +429,12 @@ int do_migrate(Monitor *mon, const QDict *qdict, QObject **ret_data)
>           return -1;
>       }
>
> +    if (migration_blockers) {
> +        Error *err = migration_blockers->data;
> +        qerror_report_err(err);
> +        return -1;
> +    }
> +
>       s = migrate_init(mon, detach, blk, inc);
>
>       if (strstart(uri, "tcp:",&p)) {
> diff --git a/migration.h b/migration.h
> index 1b8ee58..0682179 100644
> --- a/migration.h
> +++ b/migration.h
> @@ -17,6 +17,7 @@
>   #include "qdict.h"
>   #include "qemu-common.h"
>   #include "notify.h"
> +#include "error.h"
>
>   typedef struct MigrationState MigrationState;
>
> @@ -89,4 +90,18 @@ int ram_load(QEMUFile *f, void *opaque, int version_id);
>
>   extern int incoming_expected;
>
> +/**
> + * @migrate_add_blocker - prevent migration from proceeding
> + *
> + * @reason - an error to be returned whenever migration is attempted
> + */
> +void migrate_add_blocker(Error *reason);
> +
> +/**
> + * @migrate_del_blocker - remove a blocking error from migration
> + *
> + * @reason - the error blocking migration
> + */
> +void migrate_del_blocker(Error *reason);
> +
>   #endif