linux-kernel - Re: [PATCH] irq_work: Don't reinvent the wheel but use existing llist API

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Date:   Fri, 10 Nov 2017 00:17:53 +0000
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Frederic Weisbecker <frederic@...nel.org>,
        "Ingo Molnar" <mingo@...nel.org>
Cc:     "LKML" <linux-kernel@...r.kernel.org>,
        "Byungchul Park" <byungchul.park@....com>,
        "Frederic Weisbecker" <frederic@...nel.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        Petri Latvala <petri.latvala@...el.com>
Subject: Re: [PATCH] irq_work: Don't reinvent the wheel but use existing llist API

Quoting Frederic Weisbecker (2017-10-31 01:46:54)
> From: Byungchul Park <byungchul.park@....com>
> 
> Although llist provides proper APIs, they are not used. Make them used.
> 
> Signed-off-by: Byungchul Park <byungchul.park@....com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> ---
>  kernel/irq_work.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/kernel/irq_work.c b/kernel/irq_work.c
> index bcf107c..e2ebe8c 100644
> --- a/kernel/irq_work.c
> +++ b/kernel/irq_work.c
> @@ -138,11 +138,7 @@ static void irq_work_run_list(struct llist_head *list)
>                 return;
>  
>         llnode = llist_del_all(list);
> -       while (llnode != NULL) {
> -               work = llist_entry(llnode, struct irq_work, llnode);
> -
> -               llnode = llist_next(llnode);
> -
> +       llist_for_each_entry(work, llnode, llnode) {
>                 /*
>                  * Clear the PENDING bit, after this point the @work
>                  * can be re-used.

I haven't seen this reported yet, but this requires
llist_for_each_entry_safe() because as mentioned work can be linked into
another cpu's runlist after the PENDING bit is cleared.
-Chris