linux-kernel - Re: [PATCH v3 2/8] drivers/base/memory: map MMOP

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Message-ID: <CAM9Jb+heQ+Z_Hx5F-0vGLWfc4gxQRzh7am-gw+gGTJxn-7kyZA@mail.gmail.com>
Date:   Thu, 19 Mar 2020 17:29:44 +0100
From:   Pankaj Gupta <pankaj.gupta.linux@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linuxppc-dev@...ts.ozlabs.org, linux-hyperv@...r.kernel.org,
        Wei Yang <richard.weiyang@...il.com>,
        Michal Hocko <mhocko@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Oscar Salvador <osalvador@...e.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Baoquan He <bhe@...hat.com>
Subject: Re: [PATCH v3 2/8] drivers/base/memory: map MMOP_OFFLINE to 0

> Historically, we used the value -1. Just treat 0 as the special
> case now. Clarify a comment (which was wrong, when we come via
> device_online() the first time, the online_type would have been 0 /
> MEM_ONLINE). The default is now always MMOP_OFFLINE. This removes the
> last user of the manual "-1", which didn't use the enum value.
>
> This is a preparation to use the online_type as an array index.
>
> Reviewed-by: Wei Yang <richard.weiyang@...il.com>
> Acked-by: Michal Hocko <mhocko@...e.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: Baoquan He <bhe@...hat.com>
> Cc: Wei Yang <richard.weiyang@...il.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>  drivers/base/memory.c          | 11 ++++-------
>  include/linux/memory_hotplug.h |  2 +-
>  2 files changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 8c5ce42c0fc3..e7e77cafef80 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -211,17 +211,14 @@ static int memory_subsys_online(struct device *dev)
>                 return 0;
>
>         /*
> -        * If we are called from state_store(), online_type will be
> -        * set >= 0 Otherwise we were called from the device online
> -        * attribute and need to set the online_type.
> +        * When called via device_online() without configuring the online_type,
> +        * we want to default to MMOP_ONLINE.
>          */
> -       if (mem->online_type < 0)
> +       if (mem->online_type == MMOP_OFFLINE)
>                 mem->online_type = MMOP_ONLINE;
>
>         ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
> -
> -       /* clear online_type */
> -       mem->online_type = -1;
> +       mem->online_type = MMOP_OFFLINE;
>
>         return ret;
>  }
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 3aaf00db224c..76f3c617a8ab 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -48,7 +48,7 @@ enum {
>  /* Types for control the zone type of onlined and offlined memory */
>  enum {
>         /* Offline the memory. */
> -       MMOP_OFFLINE = -1,
> +       MMOP_OFFLINE = 0,
>         /* Online the memory. Zone depends, see default_zone_for_pfn(). */
>         MMOP_ONLINE,
>         /* Online the memory to ZONE_NORMAL. */
> --
> 2.24.1

Looks good to me.
Acked-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>
>
>