Re: [Qemu-devel] [PATCH 2/2] migration: store globalstate in pre_safe

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> We use global state in both savevm & migration.  The easiest way is to
> put the setup in a single place.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>

I don't think this works;  I think pre-save is called after the migration
code has changed the runstate, so you end up saving the wrong runstate,
and that explains the error Christian sees.

Dave

> ---
>  migration/migration.c | 30 ++++++++++++------------------
>  1 file changed, 12 insertions(+), 18 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index ba82ff6..d1421fe 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -110,17 +110,6 @@ typedef struct {
> 
>  static GlobalState global_state;
> 
> -static int global_state_store(void)
> -{
> -    if (!runstate_store((char *)global_state.runstate,
> -                        sizeof(global_state.runstate))) {
> -        error_report("runstate name too big: %s", global_state.runstate);
> -        trace_migrate_state_too_big();
> -        return -EINVAL;
> -    }
> -    return 0;
> -}
> -
>  static bool global_state_received(void)
>  {
>      return global_state.received;
> @@ -187,6 +176,14 @@ static void global_state_pre_save(void *opaque)
>      GlobalState *s = opaque;
> 
>      trace_migrate_global_state_pre_save((char *)s->runstate);
> +
> +    if (!runstate_store((char *)global_state.runstate,
> +                        sizeof(global_state.runstate))) {
> +        error_report("runstate name too big: %s", global_state.runstate);
> +        trace_migrate_state_too_big();
> +        exit(EXIT_FAILURE);
> +    }
> +
>      s->size = strlen((char *)s->runstate) + 1;
>  }
> 
> @@ -940,13 +937,10 @@ static void *migration_thread(void *opaque)
>                  qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
>                  old_vm_running = runstate_is_running();
> 
> -                ret = global_state_store();
> -                if (!ret) {
> -                    ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
> -                    if (ret >= 0) {
> -                        qemu_file_set_rate_limit(s->file, INT64_MAX);
> -                        qemu_savevm_state_complete(s->file);
> -                    }
> +                ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
> +                if (ret >= 0) {
> +                    qemu_file_set_rate_limit(s->file, INT64_MAX);
> +                    qemu_savevm_state_complete(s->file);
>                  }
>                  qemu_mutex_unlock_iothread();
> 
> -- 
> 2.4.3
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK