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SubjectRe: [PATCH] mm: memory_hotplug: use put_device() if device_register fail
On Thu 26-04-18 21:12:09, Arvind Yadav wrote:
> if device_register() returned an error. Always use put_device()
> to give up the initialized reference and release allocated memory.

Is this patch correct? The docummentation says
* NOTE: _Never_ directly free @dev after calling this function, even
* if it returned an error! Always use put_device() to give up your
* reference instead.

but we do not have _our_ reference in this path AFAICS. Maybe this is
just a documentation issue? How have you tested this change btw.?

> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> ---
> drivers/base/memory.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index bffe861..f5e5601 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -649,13 +649,19 @@ static const struct attribute_group *memory_memblk_attr_groups[] = {
> static
> int register_memory(struct memory_block *memory)
> {
> + int ret;
> +
> memory->dev.bus = &memory_subsys;
> memory->dev.id = memory->start_section_nr / sections_per_block;
> memory->dev.release = memory_block_release;
> memory->dev.groups = memory_memblk_attr_groups;
> memory->dev.offline = memory->state == MEM_OFFLINE;
>
> - return device_register(&memory->dev);
> + ret = device_register(&memory->dev);
> + if (ret)
> + put_device(&memory->dev);
> +
> + return ret;
> }
>
> static int init_memory_block(struct memory_block **memory,
> --
> 2.7.4

--
Michal Hocko
SUSE Labs

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