Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755562AbaDNVhl (ORCPT ); Mon, 14 Apr 2014 17:37:41 -0400 Received: from mail-qa0-f47.google.com ([209.85.216.47]:49974 "EHLO mail-qa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754819AbaDNVhX (ORCPT ); Mon, 14 Apr 2014 17:37:23 -0400 From: Tejun Heo To: lizefan@huawei.com Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 05/12] cgroup: reorganize css_task_iter Date: Mon, 14 Apr 2014 17:37:03 -0400 Message-Id: <1397511430-2673-6-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1397511430-2673-1-git-send-email-tj@kernel.org> References: <1397511430-2673-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch reorganizes css_task_iter so that adding effective css support is easier. * s/->cset_link/->cset_pos/ and s/->task/->task_pos/ for consistency * ->origin_css is used to determine whether the iteration reached the last css_set. Replace it with explicit ->cset_head so that css_advance_task_iter() doesn't have to know the termination condition directly. * css_task_iter_next() currently assumes that it's walking list of cgrp_cset_link and reaches into the current cset through the current link to determine the termination conditions for task walking. As this won't always be true for effective css walking, add ->tasks_head and ->mg_tasks_head and use them to control task walking so that css_task_iter_next() doesn't have to know how css_sets are being walked. This patch doesn't make any behavior changes. The iteration logic stays unchanged after the patch. Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 9 ++++++--- kernel/cgroup.c | 33 +++++++++++++++++---------------- 2 files changed, 23 insertions(+), 19 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 33a0043..bee3905 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -842,9 +842,12 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, /* A css_task_iter should be treated as an opaque object */ struct css_task_iter { - struct cgroup_subsys_state *origin_css; - struct list_head *cset_link; - struct list_head *task; + struct list_head *cset_pos; + struct list_head *cset_head; + + struct list_head *task_pos; + struct list_head *tasks_head; + struct list_head *mg_tasks_head; }; void css_task_iter_start(struct cgroup_subsys_state *css, diff --git a/kernel/cgroup.c b/kernel/cgroup.c index f525578..bcf390f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2861,27 +2861,30 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, */ static void css_advance_task_iter(struct css_task_iter *it) { - struct list_head *l = it->cset_link; + struct list_head *l = it->cset_pos; struct cgrp_cset_link *link; struct css_set *cset; /* Advance to the next non-empty css_set */ do { l = l->next; - if (l == &it->origin_css->cgroup->cset_links) { - it->cset_link = NULL; + if (l == it->cset_head) { + it->cset_pos = NULL; return; } link = list_entry(l, struct cgrp_cset_link, cset_link); cset = link->cset; } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); - it->cset_link = l; + it->cset_pos = l; if (!list_empty(&cset->tasks)) - it->task = cset->tasks.next; + it->task_pos = cset->tasks.next; else - it->task = cset->mg_tasks.next; + it->task_pos = cset->mg_tasks.next; + + it->tasks_head = &cset->tasks; + it->mg_tasks_head = &cset->mg_tasks; } /** @@ -2907,8 +2910,8 @@ void css_task_iter_start(struct cgroup_subsys_state *css, down_read(&css_set_rwsem); - it->origin_css = css; - it->cset_link = &css->cgroup->cset_links; + it->cset_pos = &css->cgroup->cset_links; + it->cset_head = it->cset_pos; css_advance_task_iter(it); } @@ -2924,12 +2927,10 @@ void css_task_iter_start(struct cgroup_subsys_state *css, struct task_struct *css_task_iter_next(struct css_task_iter *it) { struct task_struct *res; - struct list_head *l = it->task; - struct cgrp_cset_link *link = list_entry(it->cset_link, - struct cgrp_cset_link, cset_link); + struct list_head *l = it->task_pos; /* If the iterator cg is NULL, we have no tasks */ - if (!it->cset_link) + if (!it->cset_pos) return NULL; res = list_entry(l, struct task_struct, cg_list); @@ -2940,13 +2941,13 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it) */ l = l->next; - if (l == &link->cset->tasks) - l = link->cset->mg_tasks.next; + if (l == it->tasks_head) + l = it->mg_tasks_head->next; - if (l == &link->cset->mg_tasks) + if (l == it->mg_tasks_head) css_advance_task_iter(it); else - it->task = l; + it->task_pos = l; return res; } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/