Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755601AbaDNVmi (ORCPT ); Mon, 14 Apr 2014 17:42:38 -0400 Received: from mail-qa0-f46.google.com ([209.85.216.46]:57885 "EHLO mail-qa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755317AbaDNVhT (ORCPT ); Mon, 14 Apr 2014 17:37:19 -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 03/12] cgroup: implement cgroup->e_csets[] Date: Mon, 14 Apr 2014 17:37:01 -0400 Message-Id: <1397511430-2673-4-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 On the default unified hierarchy, a cgroup may be associated with csses of its ancestors, which means that a css of a given cgroup may be associated with css_sets of descendant cgroups. This means that we can't walk all tasks associated with a css by iterating the css_sets associated with the cgroup as there are css_sets which are pointing to the css but linked on the descendants. This patch adds per-subsystem list heads cgroup->e_csets[]. Any css_set which is pointing to a css is linked to css->cgroup->e_csets[$SUBSYS_ID] through css_set->e_cset_node[$SUBSYS_ID]. The lists are protected by css_set_rwsem and will allow us to walk all css_sets associated with a given css so that we can find out all associated tasks. Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 18 ++++++++++++++++++ kernel/cgroup.c | 30 ++++++++++++++++++++++++++++-- 2 files changed, 46 insertions(+), 2 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 1b5b2fe..33a0043 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -188,6 +188,15 @@ struct cgroup { struct list_head cset_links; /* + * On the default hierarchy, a css_set for a cgroup with some + * susbsys disabled will point to css's which are associated with + * the closest ancestor which has the subsys enabled. The + * following lists all css_sets which point to this cgroup's css + * for the given subsystem. + */ + struct list_head e_csets[CGROUP_SUBSYS_COUNT]; + + /* * Linked list running through all cgroups that can * potentially be reaped by the release agent. Protected by * release_list_lock @@ -369,6 +378,15 @@ struct css_set { struct cgroup *mg_src_cgrp; struct css_set *mg_dst_cset; + /* + * On the default hierarhcy, ->subsys[ssid] may point to a css + * attached to an ancestor instead of the cgroup this css_set is + * associated with. The following node is anchored at + * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to + * iterate through all css's attached to a given cgroup. + */ + struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; + /* For RCU-protected deletion */ struct rcu_head rcu_head; }; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a6a438f..29e8698 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -425,6 +425,8 @@ static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) static void put_css_set_locked(struct css_set *cset, bool taskexit) { struct cgrp_cset_link *link, *tmp_link; + struct cgroup_subsys *ss; + int ssid; lockdep_assert_held(&css_set_rwsem); @@ -432,6 +434,8 @@ static void put_css_set_locked(struct css_set *cset, bool taskexit) return; /* This css_set is dead. unlink it and release cgroup refcounts */ + for_each_subsys(ss, ssid) + list_del(&cset->e_cset_node[ssid]); hash_del(&cset->hlist); css_set_count--; @@ -673,7 +677,9 @@ static struct css_set *find_css_set(struct css_set *old_cset, struct css_set *cset; struct list_head tmp_links; struct cgrp_cset_link *link; + struct cgroup_subsys *ss; unsigned long key; + int ssid; lockdep_assert_held(&cgroup_mutex); @@ -724,10 +730,14 @@ static struct css_set *find_css_set(struct css_set *old_cset, css_set_count++; - /* Add this cgroup group to the hash table */ + /* Add @cset to the hash table */ key = css_set_hash(cset->subsys); hash_add(css_set_table, &cset->hlist, key); + for_each_subsys(ss, ssid) + list_add_tail(&cset->e_cset_node[ssid], + &cset->subsys[ssid]->cgroup->e_csets[ssid]); + up_write(&css_set_rwsem); return cset; @@ -1028,7 +1038,7 @@ static int rebind_subsystems(struct cgroup_root *dst_root, unsigned long ss_mask) { struct cgroup_subsys *ss; - int ssid, ret; + int ssid, i, ret; lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); @@ -1081,6 +1091,7 @@ static int rebind_subsystems(struct cgroup_root *dst_root, for_each_subsys(ss, ssid) { struct cgroup_root *src_root; struct cgroup_subsys_state *css; + struct css_set *cset; if (!(ss_mask & (1 << ssid))) continue; @@ -1095,6 +1106,12 @@ static int rebind_subsystems(struct cgroup_root *dst_root, ss->root = dst_root; css->cgroup = &dst_root->cgrp; + down_write(&css_set_rwsem); + hash_for_each(css_set_table, i, cset, hlist) + list_move_tail(&cset->e_cset_node[ss->id], + &dst_root->cgrp.e_csets[ss->id]); + up_write(&css_set_rwsem); + src_root->subsys_mask &= ~(1 << ssid); src_root->cgrp.child_subsys_mask &= ~(1 << ssid); @@ -1417,6 +1434,9 @@ out_unlock: static void init_cgroup_housekeeping(struct cgroup *cgrp) { + struct cgroup_subsys *ss; + int ssid; + atomic_set(&cgrp->refcnt, 1); INIT_LIST_HEAD(&cgrp->sibling); INIT_LIST_HEAD(&cgrp->children); @@ -1425,6 +1445,9 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->pidlists); mutex_init(&cgrp->pidlist_mutex); cgrp->dummy_css.cgroup = cgrp; + + for_each_subsys(ss, ssid) + INIT_LIST_HEAD(&cgrp->e_csets[ssid]); } static void init_cgroup_root(struct cgroup_root *root, @@ -4253,6 +4276,9 @@ int __init cgroup_init(void) if (!ss->early_init) cgroup_init_subsys(ss); + list_add_tail(&init_css_set.e_cset_node[ssid], + &cgrp_dfl_root.cgrp.e_csets[ssid]); + /* * cftype registration needs kmalloc and can't be done * during early_init. Register base cftypes separately. -- 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/