Re: [RFC PATCH 2/4] x86/dom0: make goto jump forward

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.11.2023 11:33, Nicola Vetrini wrote:
> The jump to the label 'parse_error' becomes forward, rather
> than backward; at the same time, the else branch can be eliminated.

What "else branch" is this referring to?

> This also fixes a violation of MISRA C:2012 Rule 15.2.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> ---
>  xen/arch/x86/dom0_build.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/x86/dom0_build.c b/xen/arch/x86/dom0_build.c
> index 09fb8b063ae7..f0191dc148a2 100644
> --- a/xen/arch/x86/dom0_build.c
> +++ b/xen/arch/x86/dom0_build.c
> @@ -439,12 +439,7 @@ static void __init process_dom0_ioports_disable(struct 
> domain *dom0)
>      {
>          io_from = simple_strtoul(t, &u, 16);
>          if ( u == t )
> -        {
> -        parse_error:
> -            printk("Invalid ioport range <%s> "
> -                   "in dom0_ioports_disable, skipping\n", t);
> -            continue;
> -        }
> +            goto parse_error;
>  
>          if ( *u == '\0' )
>              io_to = io_from;
> @@ -454,7 +449,12 @@ static void __init process_dom0_ioports_disable(struct 
> domain *dom0)
>              goto parse_error;
>  
>          if ( (*u != '\0') || (io_to < io_from) || (io_to >= 65536) )
> -            goto parse_error;
> +        {
> +        parse_error:
> +            printk("Invalid ioport range <%s> "
> +                   "in dom0_ioports_disable, skipping\n", t);
> +            continue;
> +        }
>  
>          printk("Disabling dom0 access to ioport range %04lx-%04lx\n",
>              io_from, io_to);

While purely from how the change looks I think I could live with this kind
of code adjustment (not a lot of churn, in particular no re-indentation,
no potentially harder to follow use of [new] local variables), this is
precisely one of the cases where I think having the label appear before
the goto is actually better, for matching how the language works otherwise
(things you want to use first need to be declared / defined).

Jan