linux-kernel - Re: [PATCH v1 2/5] drivers/base/memory: map MMOP

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Date:   Wed, 11 Mar 2020 14:18:20 +0000
From:   Wei Yang <richard.weiyang@...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,
        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>,
        Wei Yang <richard.weiyang@...il.com>
Subject: Re: [PATCH v1 2/5] drivers/base/memory: map MMOP_OFFLINE to 0

On Wed, Mar 11, 2020 at 01:30:23PM +0100, David Hildenbrand wrote:
>I have no idea why we have to start at -1. Just treat 0 as the special
>case. 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 is a preparation to use the online_type as an array index.
>
>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>

Reviewed-by: Wei Yang <richard.weiyang@...il.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 261dbf010d5d..c2e06ed5e0e9 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

-- 
Wei Yang
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