Re: [PATCH v4 05/31] scripts: add script to fix error_append_hint/error_prepend usage

[Eric Blake <eblake@redhat.com>]

On 10/1/19 10:52 AM, Vladimir Sementsov-Ogievskiy wrote:
> error_append_hint and error_prepend will not work, if errp ==
> &fatal_error, as program will exit before error_append_hint or
> error_prepend call. Fix this by use of special macro
> ERRP_AUTO_PROPAGATE.

This patch doesn't actually fix any code, but adds the script to enable 
automating the fixing of the code in subsequent patches.  Tweaking the 
commit message to make that point clear might be helpful.


>   scripts/coccinelle/fix-error-add-info.cocci | 28 +++++++++++++++++++++
>   1 file changed, 28 insertions(+)
>   create mode 100644 scripts/coccinelle/fix-error-add-info.cocci
> 
> diff --git a/scripts/coccinelle/fix-error-add-info.cocci b/scripts/coccinelle/fix-error-add-info.cocci
> new file mode 100644
> index 0000000000..34fa3be720
> --- /dev/null
> +++ b/scripts/coccinelle/fix-error-add-info.cocci
> @@ -0,0 +1,28 @@
> +@rule0@
> +// Add invocation to errp-functions
> +identifier fn;
> +@@
> +
> + fn(..., Error **errp, ...)
> + {
> ++   ERRP_AUTO_PROPAGATE();
> +    <+...
> +(
> +    error_append_hint(errp, ...);
> +|
> +    error_prepend(errp, ...);
> +)

So, for now, you aren't addressing any *errp usage, or any potential 
cleanups of error_propagate.  But that's okay; your cover letter did 
call out that you were only addressing 1 part out of 3 potential uses 
just to get some motion, based on the size of the effort.

> +    ...+>
> + }
> +
> +@@
> +// Drop doubled invocation
> +identifier rule0.fn;
> +@@
> +
> + fn(...)
> +{
> +    ERRP_AUTO_PROPAGATE();
> +-   ERRP_AUTO_PROPAGATE();
> +    ...
> +}
> 

This looks idempotent once a file is patched, and safe to rerun as many 
times in the future as needed.  I'm still hoping we can find a way to 
make scripts/checkpatch.pl also do a sanity check, but as it's harder to 
parse C in perl than in Coccinelle, I can live with just the .cocci 
script in-tree as long as we remember to manually run it periodically.

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

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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