From patchwork Mon Dec 7 22:38:50 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 553643 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id D2C84140187 for ; Tue, 8 Dec 2015 09:42:56 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b=ZcItIA5S; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964850AbbLGWmJ (ORCPT ); Mon, 7 Dec 2015 17:42:09 -0500 Received: from mail-qk0-f182.google.com ([209.85.220.182]:36846 "EHLO mail-qk0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933048AbbLGWjI (ORCPT ); Mon, 7 Dec 2015 17:39:08 -0500 Received: by qkht125 with SMTP id t125so2951175qkh.3; Mon, 07 Dec 2015 14:39:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=rQblOgJqhs94/smqbsU0nZRtX57zYzCwA+FTAiJfd9o=; b=ZcItIA5SOXY4DccO+yYNQeaF8hEyd7/Qvzs7ymQaOIM1bO8Y4SP9aaVwr5dHMATryW bxlzw8cmTuEkfLMA02CWVHiJb5NZFxJWCrrD5vsT3QzgI3MEsHxaBK9pNHAgDAdyzPTu SsgvuoxIynfdVpsyR8KALbWtDU1Pa8r5MWr42BKwIHcv8QkPG+lmlTfkp23Eo6WKPMmb M8qVIxvtSGF65GqPl41wmaRWCsaZgKppeyrbPKnibEUo6nmNWs+1+JDRtCwkKU+qKI/G yl6T1yw3i7eVqgiER1hN3GRqsJQFfHSfA/nPs5z2E0U4G6YyK+1QfukKM5uNTGBxn0u8 Z7+w== X-Received: by 10.13.218.198 with SMTP id c189mr121668ywe.165.1449527946944; Mon, 07 Dec 2015 14:39:06 -0800 (PST) Received: from localhost ([2620:10d:c091:200::a:2a2b]) by smtp.gmail.com with ESMTPSA id h130sm182803ywb.24.2015.12.07.14.39.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Dec 2015 14:39:06 -0800 (PST) From: Tejun Heo To: davem@davemloft.net, pablo@netfilter.org, kaber@trash.net, kadlec@blackhole.kfki.hu, daniel@iogearbox.net, daniel.wagner@bmw-carit.de, nhorman@tuxdriver.com Cc: lizefan@huawei.com, hannes@cmpxchg.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, ninasc@fb.com, Tejun Heo Subject: [PATCH 3/8] cgroup: implement cgroup_get_from_path() and expose cgroup_put() Date: Mon, 7 Dec 2015 17:38:50 -0500 Message-Id: <1449527935-27056-4-git-send-email-tj@kernel.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1449527935-27056-1-git-send-email-tj@kernel.org> References: <1449527935-27056-1-git-send-email-tj@kernel.org> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Implement cgroup_get_from_path() using kernfs_walk_and_get() which obtains a default hierarchy cgroup from its path. This will be used to allow cgroup path based matching from outside cgroup proper - e.g. networking and perf. v2: Add EXPORT_SYMBOL_GPL(cgroup_get_from_path). Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 7 +++++++ kernel/cgroup.c | 39 ++++++++++++++++++++++++++++++++++----- 2 files changed, 41 insertions(+), 5 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b5ee2c4..4c3ffab 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -81,6 +81,8 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup, struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, struct cgroup_subsys *ss); +struct cgroup *cgroup_get_from_path(const char *path); + int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); @@ -351,6 +353,11 @@ static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n) percpu_ref_put_many(&css->refcnt, n); } +static inline void cgroup_put(struct cgroup *cgrp) +{ + css_put(&cgrp->self); +} + /** * task_css_set_check - obtain a task's css_set with extra access conditions * @task: the task to obtain css_set for diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3190040..3db5e8f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -434,11 +434,6 @@ static bool cgroup_tryget(struct cgroup *cgrp) return css_tryget(&cgrp->self); } -static void cgroup_put(struct cgroup *cgrp) -{ - css_put(&cgrp->self); -} - struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) { struct cgroup *cgrp = of->kn->parent->priv; @@ -5753,6 +5748,40 @@ struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) return id > 0 ? idr_find(&ss->css_idr, id) : NULL; } +/** + * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path + * @path: path on the default hierarchy + * + * Find the cgroup at @path on the default hierarchy, increment its + * reference count and return it. Returns pointer to the found cgroup on + * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR) + * if @path points to a non-directory. + */ +struct cgroup *cgroup_get_from_path(const char *path) +{ + struct kernfs_node *kn; + struct cgroup *cgrp; + + mutex_lock(&cgroup_mutex); + + kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); + if (kn) { + if (kernfs_type(kn) == KERNFS_DIR) { + cgrp = kn->priv; + cgroup_get(cgrp); + } else { + cgrp = ERR_PTR(-ENOTDIR); + } + kernfs_put(kn); + } else { + cgrp = ERR_PTR(-ENOENT); + } + + mutex_unlock(&cgroup_mutex); + return cgrp; +} +EXPORT_SYMBOL_GPL(cgroup_get_from_path); + #ifdef CONFIG_CGROUP_DEBUG static struct cgroup_subsys_state * debug_css_alloc(struct cgroup_subsys_state *parent_css)