linux-kernel - Re: [RESEND PATCH] irq_work: improve the flag definitions

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Date:   Mon, 11 Dec 2017 11:59:22 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        Frederic Weisbecker <fweisbec@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <brgl@...ev.pl>
Subject: Re: [RESEND PATCH] irq_work: improve the flag definitions

2017-11-27 11:52 GMT+01:00 Bartosz Golaszewski <brgl@...ev.pl>:
> IRQ_WORK_FLAGS is defined simply to 3UL. This is confusing as it
> says nothing about its purpose. Define IRQ_WORK_FLAGS as a bitwise
> OR of IRQ_WORK_PENDING and IRQ_WORK_BUSY and change its name to
> IRQ_WORK_CLAIMED.
>
> While we're at it: use the BIT() macro for all flags.
>
> Signed-off-by: Bartosz Golaszewski <brgl@...ev.pl>
> ---
>  include/linux/irq_work.h | 8 ++++----
>  kernel/irq_work.c        | 2 +-
>  2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
> index 0e81035b678f..de6333967d61 100644
> --- a/include/linux/irq_work.h
> +++ b/include/linux/irq_work.h
> @@ -13,10 +13,10 @@
>   * busy      NULL, 2 -> {free, claimed} : callback in progress, can be claimed
>   */
>
> -#define IRQ_WORK_PENDING       1UL
> -#define IRQ_WORK_BUSY          2UL
> -#define IRQ_WORK_FLAGS         3UL
> -#define IRQ_WORK_LAZY          4UL /* Doesn't want IPI, wait for tick */
> +#define IRQ_WORK_PENDING       BIT(0)
> +#define IRQ_WORK_BUSY          BIT(1)
> +#define IRQ_WORK_CLAIMED       (IRQ_WORK_PENDING | IRQ_WORK_BUSY)
> +#define IRQ_WORK_LAZY          BIT(2) /* Doesn't want IPI, wait for tick */
>
>  struct irq_work {
>         unsigned long flags;
> diff --git a/kernel/irq_work.c b/kernel/irq_work.c
> index 40e9d739c169..6b7cdf17ccf8 100644
> --- a/kernel/irq_work.c
> +++ b/kernel/irq_work.c
> @@ -36,7 +36,7 @@ static bool irq_work_claim(struct irq_work *work)
>          */
>         flags = work->flags & ~IRQ_WORK_PENDING;
>         for (;;) {
> -               nflags = flags | IRQ_WORK_FLAGS;
> +               nflags = flags | IRQ_WORK_CLAIMED;
>                 oflags = cmpxchg(&work->flags, flags, nflags);
>                 if (oflags == flags)
>                         break;
> --
> 2.15.0
>

It's been a couple months since I first posted this patch. Can it be
applied for 4.16?

@Frederic: I noticed you picked up some irq_work patches in the past
so I'm Cc'ing you.

Best regards,
Bartosz Golaszewski