Re: [PATCH] block: uapi: Fix compilation errors using ioprio.h with C++

[Igor Pylypiv <ipylypiv@google.com>]

On Tue, Aug 15, 2023 at 06:58:32AM +0900, Damien Le Moal wrote:
> The use of the "class" argument name in the ioprio_value() inline
> function in include/uapi/linux/ioprio.h confuses C++ compilers
> resulting in compilation errors such as:
> 
> /usr/include/linux/ioprio.h:110:43: error: expected primary-expression before ‘int’
>   110 | static __always_inline __u16 ioprio_value(int class, int level, int hint)
>       |                                           ^~~
> 
> for user C++ programs including linux/ioprio.h.
> 
> Avoid these errors by renaming the arguments of the ioprio_value()
> function to prioclass, priolevel and priohint. For consistency, the
> arguments of the IOPRIO_PRIO_VALUE() and IOPRIO_PRIO_VALUE_HINT() macros
> are also renamed in the same manner.
> 
> Reported-by: Igor Pylypiv <ipylypiv@google.com>
> Fixes: 01584c1e2337 ("scsi: block: Improve ioprio value validity checks")
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

Tested-by: Igor Pylypiv <ipylypiv@google.com>

Thanks!
> ---
>  include/uapi/linux/ioprio.h | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
> index 99440b2e8c35..bee2bdb0eedb 100644
> --- a/include/uapi/linux/ioprio.h
> +++ b/include/uapi/linux/ioprio.h
> @@ -107,20 +107,21 @@ enum {
>  /*
>   * Return an I/O priority value based on a class, a level and a hint.
>   */
> -static __always_inline __u16 ioprio_value(int class, int level, int hint)
> +static __always_inline __u16 ioprio_value(int prioclass, int priolevel,
> +					  int priohint)
>  {
> -	if (IOPRIO_BAD_VALUE(class, IOPRIO_NR_CLASSES) ||
> -	    IOPRIO_BAD_VALUE(level, IOPRIO_NR_LEVELS) ||
> -	    IOPRIO_BAD_VALUE(hint, IOPRIO_NR_HINTS))
> +	if (IOPRIO_BAD_VALUE(prioclass, IOPRIO_NR_CLASSES) ||
> +	    IOPRIO_BAD_VALUE(priolevel, IOPRIO_NR_LEVELS) ||
> +	    IOPRIO_BAD_VALUE(priohint, IOPRIO_NR_HINTS))
>  		return IOPRIO_CLASS_INVALID << IOPRIO_CLASS_SHIFT;
>  
> -	return (class << IOPRIO_CLASS_SHIFT) |
> -		(hint << IOPRIO_HINT_SHIFT) | level;
> +	return (prioclass << IOPRIO_CLASS_SHIFT) |
> +		(priohint << IOPRIO_HINT_SHIFT) | priolevel;
>  }
>  
> -#define IOPRIO_PRIO_VALUE(class, level)			\
> -	ioprio_value(class, level, IOPRIO_HINT_NONE)
> -#define IOPRIO_PRIO_VALUE_HINT(class, level, hint)	\
> -	ioprio_value(class, level, hint)
> +#define IOPRIO_PRIO_VALUE(prioclass, priolevel)			\
> +	ioprio_value(prioclass, priolevel, IOPRIO_HINT_NONE)
> +#define IOPRIO_PRIO_VALUE_HINT(prioclass, priolevel, priohint)	\
> +	ioprio_value(prioclass, priolevel, priohint)
>  
>  #endif /* _UAPI_LINUX_IOPRIO_H */
> -- 
> 2.41.0
>