Re: [PATCH for-9.0 1/2] migration: Set migration error in migration_completion()

[Peter Xu]

On Thu, Mar 28, 2024 at 04:02:51PM +0200, Avihai Horon wrote:
> After commit 9425ef3f990a ("migration: Use migrate_has_error() in
> close_return_path_on_source()"), close_return_path_on_source() assumes
> that migration error is set if an error occurs during migration.
> 
> This may not be true if migration errors in migration_completion(). For
> example, if qemu_savevm_state_complete_precopy() errors, migration error
> will not be set.
> 
> This in turn, will cause a migration hang bug, similar to the bug that
> was fixed by commit 22b04245f0d5 ("migration: Join the return path
> thread before releasing to_dst_file"), as shutdown() will not be issued
> for the return-path channel.
> 
> Fix it by ensuring migration error is set in case of error in
> migration_completion().
> 
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

I'll attach this if it looks all right to you:

Fixes: 9425ef3f990a ("migration: Use migrate_has_error() in 
close_return_path_on_source()")

Thanks,

> ---
>  migration/migration.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 9fe8fd2afd7..b73ae3a72c4 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2799,6 +2799,7 @@ static void migration_completion(MigrationState *s)
>  {
>      int ret = 0;
>      int current_active_state = s->state;
> +    Error *local_err = NULL;
>  
>      if (s->state == MIGRATION_STATUS_ACTIVE) {
>          ret = migration_completion_precopy(s, &current_active_state);
> @@ -2832,6 +2833,15 @@ static void migration_completion(MigrationState *s)
>      return;
>  
>  fail:
> +    if (qemu_file_get_error_obj(s->to_dst_file, &local_err)) {
> +        migrate_set_error(s, local_err);
> +        error_free(local_err);
> +    } else if (ret) {
> +        error_setg_errno(&local_err, -ret, "Error in migration completion");
> +        migrate_set_error(s, local_err);
> +        error_free(local_err);
> +    }
> +
>      migration_completion_failed(s, current_active_state);
>  }
>  
> -- 
> 2.26.3
> 
> 

-- 
Peter Xu