Re: [PATCH] migration/rdma: rdma_accept_incoming_migration fix error handling

[Peter Xu <peterx@redhat.com>]

On Mon, Feb 10, 2020 at 07:44:59PM +0000, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> rdma_accept_incoming_migration is called from an fd handler and
> can't return an Error * anywhere.
> Currently it's leaking Error's in errp/local_err - there's
> no point putting them in there unless we can report them.
> 
> Turn most into fprintf's, and the last into an error_reportf_err
> where it's coming up from another function.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/rdma.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/migration/rdma.c b/migration/rdma.c
> index 2379b8345b..f67161c98f 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -3980,13 +3980,13 @@ static void rdma_accept_incoming_migration(void *opaque)
>      RDMAContext *rdma = opaque;
>      int ret;
>      QEMUFile *f;
> -    Error *local_err = NULL, **errp = &local_err;
> +    Error *local_err = NULL;
>  
>      trace_qemu_rdma_accept_incoming_migration();
>      ret = qemu_rdma_accept(rdma);
>  
>      if (ret) {
> -        ERROR(errp, "RDMA Migration initialization failed!");
> +        fprintf(stderr, "RDMA ERROR: Migration initialization failed");

Is there any reason to explictly use stderr instead of the
error_reportf_err() below (then we simply jump to that for error
paths)?  The only difference of error_reportf_err() and stderr should
be when there's one HMP, while shall we always suggest to use
error_reportf_err() rather than stderr?

Thanks,

>          return;
>      }
>  
> @@ -3998,13 +3998,16 @@ static void rdma_accept_incoming_migration(void *opaque)
>  
>      f = qemu_fopen_rdma(rdma, "rb");
>      if (f == NULL) {
> -        ERROR(errp, "could not qemu_fopen_rdma!");
> +        fprintf(stderr, "RDMA ERROR: could not qemu_fopen_rdma");
>          qemu_rdma_cleanup(rdma);
>          return;
>      }
>  
>      rdma->migration_started_on_destination = 1;
> -    migration_fd_process_incoming(f, errp);
> +    migration_fd_process_incoming(f, &local_err);
> +    if (local_err) {
> +        error_reportf_err(local_err, "RDMA ERROR:");
> +    }
>  }
>  
>  void rdma_start_incoming_migration(const char *host_port, Error **errp)
> -- 
> 2.24.1
> 

-- 
Peter Xu