Re: [Xen-devel] [RFC v5 025/126] scripts: add coccinelle script to use auto propagated errp

[Eric Blake <eblake@xxxxxxxxxx>]

On 10/11/19 11:04 AM, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
> ---
>   scripts/coccinelle/auto-propagated-errp.cocci | 118 ++++++++++++++++++
>   1 file changed, 118 insertions(+)
>   create mode 100644 scripts/coccinelle/auto-propagated-errp.cocci
>
> diff --git a/scripts/coccinelle/auto-propagated-errp.cocci 
> b/scripts/coccinelle/auto-propagated-errp.cocci
> new file mode 100644
> index 0000000000..d9731620aa
> --- /dev/null
> +++ b/scripts/coccinelle/auto-propagated-errp.cocci
> +@rule1@
> +// Drop local_err
> +identifier fn, local_err;
> +symbol errp;
> +@@
> +
> + fn(..., Error **errp, ...)
> + {
> +     <...
> +-    Error *local_err = NULL;
> +     ...>
> + }
> +
So our goal is to automate removal of all local_err (including when it 
is spelled err)...
> +@@
> +// Handle pattern with goto, otherwise we'll finish up
> +// with labels at function end which will not compile.
> +identifier rule1.fn;
> +identifier rule1.local_err;
> +identifier OUT;
> +@@
> +
> + fn(...)
> + {
> +     <...
> +-    goto OUT;
> ++    return;
> +     ...>
> +- OUT:
> +-    error_propagate(errp, local_err);
> + }
> +
this dangling label cleanup makes sense

> +@@
> +identifier rule1.fn;
> +identifier rule1.local_err;
> +@@
> +
> + fn(...)
> + {
> +     <...
> +(
> +-    error_free(local_err);
> +-    local_err = NULL;
> ++    error_free_errp(errp);
This does not make sense - error_free_errp() is not defined prior to 
this series or anywhere in patches 1-24, if I'm reading it correctly.
> +|
> +-    error_free(local_err);
> ++    error_free_errp(errp);
and again

> +|
> +-    error_report_err(local_err);
> ++    error_report_errp(errp);
> +|
> +-    warn_report_err(local_err);
> ++    warn_report_errp(errp);
> +|
> +-    error_propagate_prepend(errp, local_err,
> ++    error_prepend(errp,
> +                              ...);
> +|
> +-    error_propagate(errp, local_err);
> +)
> +     ...>
> + }
> +
It looks like once this script is run, error_propagate_prepend() will 
have no clients.  Is there a non-generated cleanup patch that removes it 
(and once it is removed, it can also be removed from the .cocci script 
as no further clients will reappear later)?

> +@@
> +identifier rule1.fn;
> +identifier rule1.local_err;
> +@@
> +
> + fn(...)
> + {
> +     <...
> +(
> +-    &local_err
> ++    errp
> +|
> +-    local_err
> ++    *errp
> +)
> +     ...>
> + }
> +
> +@@
> +symbol errp;
> +@@
> +
> +- *errp != NULL
> ++ *errp
Seems to make sense.

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

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