Re: [Qemu-devel] [PATCH 12/13] qapi: Replace uncommon use of the error API by the common one

[Eric Blake <eblake@redhat.com>]

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On 05/02/2014 06:44 AM, Markus Armbruster wrote:
> We commonly use the error API like this:
> 

> However, mixing the two techniques is confusing.  You can't use the
> "accumulate" technique with functions designed for the "check
> separately" technique.  You can use the "check separately" technique
> with functions designed for the "accumulate" technique, but then
> error_set() can't catch you setting an error more than once.

Nice comparison of the two techniques.

> 
> Standardize on the "check separately" technique for now, because it's
> overwhelmingly prevalent.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---

> +++ b/hw/virtio/virtio-balloon.c
> @@ -121,23 +121,27 @@ static void balloon_stats_get_all(Object *obj, struct Visitor *v,

>      visit_start_struct(v, NULL, NULL, "stats", 0, &err);
>      if (err) {
>          goto out_end;
>      }
> -        
> -    for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
> +    for (i = 0; err && i < VIRTIO_BALLOON_S_NR; i++) {

Oops; logic error makes this loop dead code.

s/err/!err/

> @@ -502,7 +503,7 @@ fdecl.write(mcgen('''
>  /* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
>  
>  /*
> - * schema-defined QAPI visitor function
> + * schema-defined QAPI visitor functions

Unrelated typo fix; could go in separately via -trivial if you were so
inclined, but I don't mind it going in here.

If the logic error is the only fix,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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