Re: [XEN PATCH v2 3/7] xen/list: address violations of MISRA C Rule 20.7

From: Jan Beulich <jbeulich@suse.com>
To: Nicola Vetrini <nicola.vetrini@bugseng.com>
Cc: sstabellini@kernel.org, michal.orzel@amd.com,
	xenia.ragiadakou@amd.com, ayan.kumar.halder@amd.com,
	consulting@bugseng.com, bertrand.marquis@arm.com, julien@xen.org,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>, Wei Liu <wl@xen.org>,
	xen-devel@lists.xenproject.org
Subject: Re: [XEN PATCH v2 3/7] xen/list: address violations of MISRA C Rule 20.7
Date: Mon, 11 Mar 2024 08:48:55 +0100	[thread overview]
Message-ID: <0d3af110-773e-40bd-bd95-b385f49a7c47@suse.com> (raw)
In-Reply-To: <b93a64b93ef4210f5fe96368c2522e5e71e9c87c.1709896401.git.nicola.vetrini@bugseng.com>

On 08.03.2024 12:21, Nicola Vetrini wrote:
> --- a/xen/include/xen/list.h
> +++ b/xen/include/xen/list.h
> @@ -479,9 +479,9 @@ static inline void list_splice_init(struct list_head *list,
>   * @n:      another &struct list_head to use as temporary storage
>   * @head:   the head for your list.
>   */
> -#define list_for_each_backwards_safe(pos, n, head)              \
> -    for ( pos = (head)->prev, n = pos->prev; pos != (head);     \
> -          pos = n, n = pos->prev )
> +#define list_for_each_backwards_safe(pos, n, head)                 \
> +    for ( (pos) = (head)->prev, n = (pos)->prev; (pos) != (head);  \
> +          (pos) = n, n = (pos)->prev )

I think this is worse than before and incomplete: At least the rhs use of n
also needs parenthesizing. Plus if pos is parenthesized even in lhs
instances, imo n ought to be, too.

Jan