Re: [PATCH v2 34/44] error: Eliminate error_propagate() with Coccinelle, part 1

[Eric Blake]

On 7/2/20 10:49 AM, Markus Armbruster wrote:
> When all we do with an Error we receive into a local variable is
> propagating to somewhere else, we can just as well receive it there
> right away.  Convert
>
>      if (!foo(..., &err)) {
>          ...
>          error_propagate(errp, err);
>          ...
>          return ...
>      }
>
> to
>
>      if (!foo(..., errp)) {
>          ...
>          ...
>          return ...
>      }

> Not exactly elegant, I'm afraid.

True, but it is still reasonable enough to use.

> The "when != goto lbl;" is necessary to avoid transforming

spelled "when != lbl:" above in rule1 and rule2

>           if (fun(args, &err)) {
>               goto out
>           }
>           ...
>       out:
>           error_propagate(errp, err);
>
> even though other paths to label out still need the error_propagate().
> For an actual example, see sclp_realize().
>
> Without the "when strict", Coccinelle transforms vfio_msix_setup(),
> incorrectly.  I don't know what exactly "when strict" does, only that
> it helps here.
>
> The match of return is narrower than what I want, but I can't figure
> out how to express "return where the operand doesn't use @err".  For
> an example where it's too narrow, see vfio_intx_enable().
>
> Silently fails to convert hw/arm/armsse.c, because Coccinelle gets
> confused by ARMSSE being used both as typedef and function-like macro
> there.  Converted manually.
>
> Line breaks tidied up manually.  One nested declaration of @local_err
> deleted manually.  Preexisting unwanted blank line dropped in
> hw/riscv/sifive_e.c.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---

>   114 files changed, 376 insertions(+), 884 deletions(-)

Big, but sane.  Picks up the spots I noticed in 33/44, and then some ;)

Reviewed-by: Eric Blake <eblake@redhat.com>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org