Re: [PATCH] xen: Rework WARN_ON() to return whether a warning was triggered

[Jan Beulich <jbeulich@xxxxxxxx>]

On 15.12.2020 12:26, Julien Grall wrote:
> --- a/xen/include/xen/lib.h
> +++ b/xen/include/xen/lib.h
> @@ -23,7 +23,13 @@
>  #include <asm/bug.h>
>  
>  #define BUG_ON(p)  do { if (unlikely(p)) BUG();  } while (0)
> -#define WARN_ON(p) do { if (unlikely(p)) WARN(); } while (0)
> +#define WARN_ON(p)  ({                  \
> +    bool __ret_warn_on = (p);           \

Please can you avoid leading underscores here?

> +                                        \
> +    if ( unlikely(__ret_warn_on) )      \
> +        WARN();                         \
> +    unlikely(__ret_warn_on);            \
> +})

Is this latter unlikely() having any effect? So far I thought it
would need to be immediately inside a control construct or be an
operand to && or ||.

Jan