Re: [PATCH -next v5 1/6] md: pass a md_thread pointer to md_register_thread()

[Yu Kuai]

Hi,

在 2023/04/11 9:15, Song Liu 写道:
> On Mon, Apr 10, 2023 at 4:37 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > Prepare to protect md_thread with rcu, there are no functional changes.
>
> Why do we need this change? To add __rcu later?

Add __rcu is one reason, more importantly is to assign md_thread inside
md_register_thread in patch 6:

rcu_assign_pointer(*threadp, thread);

> Can we do something like:
>
> struct md_thread __rcu *md_register_thread(void (*run) (struct md_thread *),
>                 struct mddev *mddev, const char *name)

I think this is not necessary, if we don't want to change api, we must
use rcu_assign_pointer for each caller to set md_thread.

Thanks,
Kuai
> Thanks,
> Song
> .