Re: [PATCH V2 05/11] migration: MigrationEvent for notifiers

[Steven Sistare]

On 1/12/2024 10:05 AM, Steve Sistare wrote:
> Passing MigrationState to notifiers is unsound because they could access
> unstable migration state internals or even modify the state.  Instead, pass
> the minimal info needed in a new MigrationEvent struct, which could be
> extended in the future if needed.
> 
> Suggested-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  [...]
> diff --git a/include/migration/misc.h b/include/migration/misc.h
> index dcc98bb..0b4ce0f 100644
> --- a/include/migration/misc.h
> +++ b/include/migration/misc.h
> @@ -60,6 +60,11 @@ void migration_object_init(void);
>  void migration_shutdown(void);
>  bool migration_is_idle(void);
>  bool migration_is_active(MigrationState *);
> +
> +typedef struct MigrationEvent {
> +    MigrationStatus state;
> +} MigrationEvent;

Hi Peter, I chose to pass MigrationStatus rather than define a new enum and map
MigrationStatus to it.  IMO a new enum adds little value, yet it is more code 
and
another layer of abstraction for coders to grok.  

- Steve