Re: [PATCH] perf-event/cgroup: explicitly init the early_init field

From: Ingo Molnar
Date: Tue Apr 22 2014 - 02:07:06 EST



* Jianyu Zhan <nasa4836@xxxxxxxxx> wrote:

> For a cgroup subsystem who should init early, then it should carefully
> take care of the implementation of css_alloc, because it will be called
> before mm_init() setup the world.
>
> Luckily we don't, and we better explicitly assign the early_init field
> to 0, for document reason.
>
> Signed-off-by: Jianyu Zhan <nasa4836@xxxxxxxxx>
> ---
> kernel/events/core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index f83a71a..b3a8916 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -8062,5 +8062,6 @@ struct cgroup_subsys perf_event_cgrp_subsys = {
> .css_free = perf_cgroup_css_free,
> .exit = perf_cgroup_exit,
> .attach = perf_cgroup_attach,
> + .early_init = 0,

How can that field ever be nonzero?

I.e. under what exact circumstances does this patch make sense?

Thanks,

Ingo
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