From: Tejun Heo <tj@kernel.org>
To: Aleksa Sarai <cyphar@cyphar.com>
Cc: lizefan@huawei.com, mingo@redhat.com, peterz@infradead.org,
richard@nod.at, fweisbec@gmail.com, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org
Subject: Re: [PATCH v12 7/8] cgroup: add a tset_get_css macro
Date: Mon, 18 May 2015 17:34:23 -0400 [thread overview]
Message-ID: <20150518213423.GI24861@htj.duckdns.org> (raw)
In-Reply-To: <1431960667-26593-8-git-send-email-cyphar@cyphar.com>
On Tue, May 19, 2015 at 12:51:06AM +1000, Aleksa Sarai wrote:
> This adds a macro to get the css of a tset (using task_get_css()) by
> just grabbing a ref to the first item in the tset (since there is a
> guarantee that all tasks in a tset share a css).
>
> This is in preparation for implementing the pids cgroup subsystem.
>
> Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
> ---
> include/linux/cgroup.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 886a883..773846d 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -639,6 +639,18 @@ struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
> for ((task) = cgroup_taskset_first((tset)); (task); \
> (task) = cgroup_taskset_next((tset)))
>
> +/**
> + * tset_get_css - obtain and get css for (tset, subsys_id)
> + * @tset: target taskset
> + * @subsys_id: target subsystem id
> + *
> + * Since all of the tasks in a taskset are guaranteed to have the same css, it's
> + * safe to grab the ref of just the first task's css and treat it as though you
> + * have a ref on the taskset's "collective" css.
> + */
> +#define tset_get_css(tset, subsys_id) \
> + task_get_css(cgroup_taskset_first(tset), subsys_id)
They aren't tho. It depends on the hierarchy configuration. csses
belonging to hierarchies which aren't the current migration target may
differ.
Thanks.
--
tejun
next prev parent reply other threads:[~2015-05-18 21:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-18 14:50 [PATCH v12 0/8] cgroup: add pids subsystem Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 1/8] cgroup: switch to unsigned long for bitmasks Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 2/8] cgroup: use bitmask to filter for_each_subsys Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 3/8] cgroup: replace explicit ss_mask checking with for_each_subsys_which Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 4/8] cgroup, block: implement task_get_css() and use it in bio_associate_current() Aleksa Sarai
2015-05-18 21:59 ` Tejun Heo
2015-05-19 3:05 ` Aleksa Sarai
2015-05-28 20:47 ` Tejun Heo
2015-05-18 14:51 ` [PATCH v12 5/8] cgroup: move enum cgroup_subsys_id definition Aleksa Sarai
2015-05-18 21:59 ` Tejun Heo
2015-05-19 1:25 ` Aleksa Sarai
2015-05-28 20:44 ` Tejun Heo
2015-05-18 14:51 ` [PATCH v12 6/8] cgroup: allow a cgroup subsystem to reject a fork Aleksa Sarai
2015-05-18 22:12 ` Tejun Heo
2015-05-18 14:51 ` [PATCH v12 7/8] cgroup: add a tset_get_css macro Aleksa Sarai
2015-05-18 21:34 ` Tejun Heo [this message]
2015-05-19 1:18 ` Aleksa Sarai
2015-05-18 14:51 ` [PATCH v12 8/8] cgroup: implement the PIDs subsystem Aleksa Sarai
2015-05-19 8:00 ` Peter Zijlstra
2015-05-19 8:44 ` Aleksa Sarai
2015-05-19 10:56 ` Peter Zijlstra
2015-05-28 20:33 ` Tejun Heo
2015-05-19 13:11 ` Thomas Gleixner
2015-05-19 13:43 ` Aleksa Sarai
2015-06-03 2:44 ` Aleksa Sarai
2015-05-28 20:40 ` Tejun Heo
2015-05-30 6:50 ` Aleksa Sarai
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