Re: [PATCH 12/12] error: Kill @error_warn

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Aug 08, 2025 at 10:08:23AM +0200, Markus Armbruster wrote:
> We added @error_warn some two years ago in commit 3ffef1a55ca (error:
> add global &error_warn destination).  It has multiple issues:
> 
> * error.h's big comment was not updated for it.
> 
> * Function contracts were not updated for it.
> 
> * ERRP_GUARD() is unaware of @error_warn, and fails to mask it from
>   error_prepend() and such.  These crash on @error_warn, as pointed
>   out by Akihiko Odaki.
> 
> All fixable.  However, after more than two years, we had just of 15
> uses, of which the last few patches removed eight as unclean or
> otherwise undesirable.  I didn't look closely enough at the remaining
> seven to decide whether they are desirable or not.
> 
> I don't think this feature earns its keep.  Drop it.
> 
> Thanks-to: Akihiko  Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  include/qapi/error.h           |  6 ------
>  hw/display/virtio-gpu.c        |  8 ++++++--
>  hw/net/virtio-net.c            |  8 +++++++-
>  tests/unit/test-error-report.c | 17 -----------------
>  ui/gtk.c                       |  6 +++++-
>  util/error.c                   |  5 +----
>  6 files changed, 19 insertions(+), 31 deletions(-)

> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 6b5b5dace3..7848e26278 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1289,6 +1289,8 @@ exit:
>  
>  static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp)
>  {
> +    Error *err = NULL;
> +
>      if (!virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
>          return true;
>      }
> @@ -1306,7 +1308,11 @@ static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp)
>          return virtio_net_load_ebpf_fds(n, errp);
>      }
>  
> -    ebpf_rss_load(&n->ebpf_rss, &error_warn);
> +    ebpf_rss_load(&n->ebpf_rss, &err);
> +    /* Beware, ebpf_rss_load() can return false with @err unset */

Per our other mail, this is a bug we should fix

> +    if (err) {
> +        warn_report_err(err);
> +    }
>      return true;
>  }
>  

With regards,
Daniel
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