linux-kernel - Re: [PATCH v2] ocfs2: remove usage of list iterator variable after the loop body

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Message-ID: <47807b41-566c-f0b6-831c-658abd60861c@linux.alibaba.com>
Date:   Tue, 22 Mar 2022 18:54:07 +0800
From:   Joseph Qi <joseph.qi@...ux.alibaba.com>
To:     Jakob Koschel <jakobkoschel@...il.com>,
        Mark Fasheh <mark@...heh.com>
Cc:     linux-kernel@...r.kernel.org, ocfs2-devel@....oracle.com,
        Joel Becker <jlbec@...lplan.org>,
        Miguel Ojeda <ojeda@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>,
        Brian Johannesmeyer <bjohannesmeyer@...il.com>,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        "Bos, H.J." <h.j.bos@...nl>
Subject: Re: [PATCH v2] ocfs2: remove usage of list iterator variable after
 the loop body



On 3/22/22 6:50 PM, Jakob Koschel wrote:
> To move the list iterator variable into the list_for_each_entry_*()
> macro in the future it should be avoided to use the list iterator
> variable after the loop body.
> 
> To *never* use the list iterator variable after the loop it was
> concluded to use a separate iterator variable [1].
> 
> Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
> Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>

Looks good to me.
Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>

> ---
>  fs/ocfs2/dlm/dlmdebug.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
> index d442cf5dda8a..be5e9ed7da8d 100644
> --- a/fs/ocfs2/dlm/dlmdebug.c
> +++ b/fs/ocfs2/dlm/dlmdebug.c
> @@ -541,7 +541,7 @@ static void *lockres_seq_start(struct seq_file *m, loff_t *pos)
>  	struct debug_lockres *dl = m->private;
>  	struct dlm_ctxt *dlm = dl->dl_ctxt;
>  	struct dlm_lock_resource *oldres = dl->dl_res;
> -	struct dlm_lock_resource *res = NULL;
> +	struct dlm_lock_resource *res = NULL, *iter;
>  	struct list_head *track_list;
>  
>  	spin_lock(&dlm->track_lock);
> @@ -556,11 +556,11 @@ static void *lockres_seq_start(struct seq_file *m, loff_t *pos)
>  		}
>  	}
>  
> -	list_for_each_entry(res, track_list, tracking) {
> -		if (&res->tracking == &dlm->tracking_list)
> -			res = NULL;
> -		else
> -			dlm_lockres_get(res);
> +	list_for_each_entry(iter, track_list, tracking) {
> +		if (&iter->tracking != &dlm->tracking_list) {
> +			dlm_lockres_get(iter);
> +			res = iter;
> +		}
>  		break;
>  	}
>  	spin_unlock(&dlm->track_lock);
> 
> base-commit: f443e374ae131c168a065ea1748feac6b2e76613