Re: [PATCH] rcu: better document kfree_rcu()

[Uladzislau Rezki <urezki@gmail.com>]

On Thu, Jan 14, 2021 at 08:22:02AM +0100, Mauro Carvalho Chehab wrote:
> After changeset 5130b8fd0690 ("rcu: Introduce kfree_rcu() single-argument macro"),
> kernel-doc now emits two warnings:
> 
> 	./include/linux/rcupdate.h:884: warning: Excess function parameter 'ptr' description in 'kfree_rcu'
> 	./include/linux/rcupdate.h:884: warning: Excess function parameter 'rhf' description in 'kfree_rcu'
> 
> What's happening here is that some macro magic was added in order
> to call two different versions of kfree_rcu(), being the first one
> with just one argument and a second one with two arguments.
> 
> That makes harder to document the kfree_rcu() arguments, which
> also reflects on the documentation text.
> 
> In order to make clearer that this macro accepts optional
> arguments, by using macro concatenation, changing its
> definition from:
> 	#define kfree_rcu kvfree_rcu
> 
> to:
> 	#define kfree_rcu(ptr, rhf...) kvfree_rcu(ptr, ## rhf)
> 
> That not only helps kernel-doc to understand the macro arguemnts,
> but also provides a better C definition that makes clearer that
> the first argument is mandatory and the second one is optional.
> 
> Fixes: 5130b8fd0690 ("rcu: Introduce kfree_rcu() single-argument macro")
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> ---
>  include/linux/rcupdate.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index bd04f722714f..5cc6deaa5df2 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -881,7 +881,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
>   * The BUILD_BUG_ON check must not involve any function calls, hence the
>   * checks are done in macros here.
>   */
> -#define kfree_rcu kvfree_rcu
> +#define kfree_rcu(ptr, rhf...) kvfree_rcu(ptr, ## rhf)
>  
>  /**
>   * kvfree_rcu() - kvfree an object after a grace period.
> -- 
> 2.29.2
> 
I think it is fair enough. I checked the "kernel-doc" and after this
change it does not detect any violations which are in question.

Tested-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

--
Vlad Rezki