Re: [PATCH] kthread: Implement park/unpark facility

[Rusty Russell]

On Tue, 5 Jun 2012 15:41:48 +0200 (CEST), Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> Subject: kthread: Implement park/unpark facility
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Date: Wed, 18 Apr 2012 16:37:40 +0200
> 
> To avoid the full teardown/setup of per cpu kthreads in the case of
> cpu hot(un)plug, provide a facility which allows to put the kthread
> into a park position and unpark it when the cpu comes online again.

Like the idea, but the API is awkward.  Now you've made returning from a
thread do different things depending on whether it was parked or not.

How about just have the thread call "kthread_parkme()" which only
returns if/when the thread is unparked?

So the thread does:

        while (!kthread_should_stop()) {
                if (kthread_should_park()) {
                        ... cleanup ...
                        kthread_parkme();
                        ... restore ...
                }
                ... work ...
        }

Threads which never exit have "for (;;)" instead of while
(!kthread_should_stop()).

Cheers,
Rusty.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/