Re: [PATCH v1 2/5] drivers/base/memory: map MMOP_OFFLINE to 0

Michal Hocko
2020-03-16T15:19:32Z

On Wed 11-03-20 13:30:23, David Hildenbrand wrote:
> I have no idea why we have to start at -1.

Because this is how the offline state offline was represented
originally.

> 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.

git grep says that you have covered the only remaining place which
hasn't used the enum value.

> This is a preparation to use the online_type as an array index.
>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Acked-by: Michal Hocko <mhocko@suse.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

--
Michal Hocko
SUSE Labs