Re: [Qemu-devel] [PATCH 01/31] Use error_fatal to simplify obvious fatal errors (again)

[Eric Blake <eblake@redhat.com>]

On 10/8/18 12:30 PM, Markus Armbruster wrote:
> Add a slight improvement of the Coccinelle semantic patch from commit
> 07d04a0219b,

which shares the same commit title, but does not actually have a 
semantic patch, but rather defers to the even older 007b065.  But I'm 
not too worried about either the duplicated commit title nor the chain 
of references to follow - as this is a no-semantic-change patch rather 
than a bugfix, it's less likely to cause confusion to any downstream 
backport efforts.

> and use it to clean up.  It leaves dead Error * variables
> behind, cleaned up manually.

Coccinelle can handle that too, if we want to make the .cocci file 
longer (but off-hand, I don't remember the exact semantic patch formula 
to express a variable that is initialized but then never used, as a 
result of applying earlier semantic patches). So the manual cleanup for 
now still seems tractable.

> 
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Eric Blake <eblake@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>   hw/intc/xics_kvm.c                       |  7 +------
>   qemu-nbd.c                               |  6 +-----
>   scripts/coccinelle/use-error_fatal.cocci | 20 ++++++++++++++++++++
>   vl.c                                     |  7 +------
>   4 files changed, 23 insertions(+), 17 deletions(-)
>   create mode 100644 scripts/coccinelle/use-error_fatal.cocci
> 

> +++ b/scripts/coccinelle/use-error_fatal.cocci
> @@ -0,0 +1,20 @@
> +@@
> +type T;
> +identifier FUN, RET;
> +expression list ARGS;
> +expression ERR, EC, FAIL;

The slight improvement from the original git commit log script is the 
addition of FAIL,

> +@@
> +(
> +-    T RET = FUN(ARGS, &ERR);
> ++    T RET = FUN(ARGS, &error_fatal);
> +|
> +-    RET = FUN(ARGS, &ERR);
> ++    RET = FUN(ARGS, &error_fatal);
> +|
> +-    FUN(ARGS, &ERR);
> ++    FUN(ARGS, &error_fatal);
> +)
> +-    if (FAIL) {

and a check for arbitrary condition FAIL rather than a more specific ERR 
!= NULL.  Makes sense.

> +-        error_report_err(ERR);
> +-        exit(EC);
> +-    }

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

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org