From patchwork Wed Nov 30 08:22:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 13059537 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9C31C433FE for ; Wed, 30 Nov 2022 08:23:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234733AbiK3IXw (ORCPT ); Wed, 30 Nov 2022 03:23:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234763AbiK3IXr (ORCPT ); Wed, 30 Nov 2022 03:23:47 -0500 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57C4243AEB; Wed, 30 Nov 2022 00:23:43 -0800 (PST) Received: by mail-pf1-x429.google.com with SMTP id k79so1631136pfd.7; Wed, 30 Nov 2022 00:23:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=K1j0A0QkOym5FfXdZ+NvM9qS4irkehDZAEMG1X/6jxM=; b=p031m+vQzbLBfL8ozACACJHzwZiZlwGL0XEKWMgbJLqVECiC1DzktHz+wtua/s/rpd AjEk+8BWWSxQrhJ06FGwz2hOwDKJxQWjrpbXQTDvzvlGDXku5XthSMzZgxZ2zVRK71Vt 2nQVXHgOs1LKMyZGCjUoIeuPkoFmvtAnYQAlwZ9EPnTnRs2tBO7EBPRc/MAFvhZFEFC4 BKW/hpV0Y4aJtSgp8tbhBre80DsR9sNf2JridkuIgJ0S2kcTX2RoNA306iBnG3crXmnH 5Xv/BvTYnnL1IAAudSfqREYp0EJpQ8mWtLd73RvYkhT5WMaa2R28iaL3UiD6PH88HXlC R+oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=K1j0A0QkOym5FfXdZ+NvM9qS4irkehDZAEMG1X/6jxM=; b=Kq8I50sPCW1UaBkBOG4J7FB1PxhhMI5acoIMzgxmJ61ktAlUT3w/9VXKL9qdA3OgYh LPMBm/q1Qn7yE44GOjamKjk3Ma4+L7NX4yWuWOBx/jBublCVrhVT7Gs95B5SDElS0gCV 9eb4sN1Onhk3WzEl9jCtMBzmoiVdgQkBmlrWEIqJe13YOUzi0BJnDPRdASbx4viI/rRZ HsGh7bQH7RfHANyWCt7bpO0lmbLLSNl0n5rzGc8OUgHqbciGVShnGtEEQZdkuaLO6C3D WKvBIEG4ErHbPXO3J/4nmRTMuIBkKka+rZrAwzTrwqykebfxPvKjwk2tcBk+/oYvizMj NOWg== X-Gm-Message-State: ANoB5pkgS76Mkc3oyarxzRntK1Z+L+y36CazwDg1ohaeiQmlBFoZaEaw Z0NBVS5dqn0n8aiQ0ba+IoI= X-Google-Smtp-Source: AA0mqf4lIvT/nRGCo9RyXdTNb2HH4H5ipD+ppktOrDLuv65JRw9ceUvN1RH8I9d7NzciEPnb4jvAig== X-Received: by 2002:a63:fa49:0:b0:476:f92f:885b with SMTP id g9-20020a63fa49000000b00476f92f885bmr42322828pgk.31.1669796622606; Wed, 30 Nov 2022 00:23:42 -0800 (PST) Received: from localhost ([2600:380:4a00:1415:d028:b547:7d35:7b0b]) by smtp.gmail.com with ESMTPSA id c10-20020a170902c1ca00b0018991f3bfb2sm776692plc.3.2022.11.30.00.23.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Nov 2022 00:23:42 -0800 (PST) Sender: Tejun Heo From: Tejun Heo To: torvalds@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, joshdon@google.com, brho@google.com, pjt@google.com, derkling@google.com, haoluo@google.com, dvernet@meta.com, dschatzberg@meta.com, dskarlat@cs.cmu.edu, riel@surriel.com Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kernel-team@meta.com, Tejun Heo Subject: [PATCH 02/31] cgroup: Implement cgroup_show_cftypes() Date: Tue, 29 Nov 2022 22:22:44 -1000 Message-Id: <20221130082313.3241517-3-tj@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221130082313.3241517-1-tj@kernel.org> References: <20221130082313.3241517-1-tj@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Implement cgroup_show_cftypes() which shows and hides all cgroup files associated with the specified set of cgroup file types. CFTYPE_HIDDEN flag is added so that files can be created hidden from the get-go. cgroup_show_cftypes() can be used whether the cftypes are added or not. It also combines with cgroup_show_file() so that a given file is visible iff both its cftype and cfile are visible. This will be used by a new sched_class to selectively show and hide CPU controller interface files depending on whether they're supported. Signed-off-by: Tejun Heo Reviewed-by: David Vernet Acked-by: Josh Don Acked-by: Hao Luo Acked-by: Barret Rhoden --- include/linux/cgroup-defs.h | 8 +++ include/linux/cgroup.h | 1 + kernel/cgroup/cgroup.c | 97 ++++++++++++++++++++++++++++++++++--- 3 files changed, 99 insertions(+), 7 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 8a0d5466c7be..8af1e7d487cb 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -127,12 +127,18 @@ enum { CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */ + CFTYPE_HIDDEN = (1 << 6), /* file type hidden, see cgroup_show_cftypes() */ + /* internal flags, do not use outside cgroup core proper */ __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ __CFTYPE_ADDED = (1 << 18), }; +enum cfile_flags { + CFILE_HIDDEN = (1 << 0), /* file instance hidden */ +}; + /* * cgroup_file is the handle for a file instance created in a cgroup which * is used, for example, to generate file changed notifications. This can @@ -140,7 +146,9 @@ enum { */ struct cgroup_file { /* do not access any fields from outside cgroup core */ + struct cftype *cft; struct kernfs_node *kn; + unsigned int flags; unsigned long notified_at; struct timer_list notify_timer; }; diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 528bd44b59e2..14fd0902bd8b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -114,6 +114,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_rm_cftypes(struct cftype *cfts); +void cgroup_show_cftype(struct cftype *cft, bool show); void cgroup_file_notify(struct cgroup_file *cfile); void cgroup_file_show(struct cgroup_file *cfile, bool show); diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index f1e6058089f5..bbfc9388bd7d 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4192,10 +4192,13 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, return ret; } + kernfs_show(kn, !(cft->flags & CFTYPE_HIDDEN)); + if (cft->file_offset) { struct cgroup_file *cfile = (void *)css + cft->file_offset; timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0); + cfile->cft = cft; spin_lock_irq(&cgroup_file_kn_lock); cfile->kn = kn; @@ -4474,6 +4477,24 @@ void cgroup_file_notify(struct cgroup_file *cfile) spin_unlock_irqrestore(&cgroup_file_kn_lock, flags); } +static struct kernfs_node *cfile_kn_get(struct cgroup_file *cfile) +{ + struct kernfs_node *kn; + + spin_lock_irq(&cgroup_file_kn_lock); + kn = cfile->kn; + kernfs_get(kn); + spin_unlock_irq(&cgroup_file_kn_lock); + + return kn; +} + +static bool cfile_visible(struct cgroup_file *cfile) +{ + return !(cfile->cft->flags & CFTYPE_HIDDEN) && + !(cfile->flags & CFILE_HIDDEN); +} + /** * cgroup_file_show - show or hide a hidden cgroup file * @cfile: target cgroup_file obtained by setting cftype->file_offset @@ -4483,15 +4504,20 @@ void cgroup_file_show(struct cgroup_file *cfile, bool show) { struct kernfs_node *kn; - spin_lock_irq(&cgroup_file_kn_lock); - kn = cfile->kn; - kernfs_get(kn); - spin_unlock_irq(&cgroup_file_kn_lock); + mutex_lock(&cgroup_mutex); - if (kn) - kernfs_show(kn, show); + if (show) + cfile->flags &= ~CFILE_HIDDEN; + else + cfile->flags |= CFILE_HIDDEN; - kernfs_put(kn); + kn = cfile_kn_get(cfile); + if (kn) { + kernfs_show(kn, cfile_visible(cfile)); + kernfs_put(kn); + } + + mutex_unlock(&cgroup_mutex); } /** @@ -5505,6 +5531,63 @@ static void offline_css(struct cgroup_subsys_state *css) wake_up_all(&css->cgroup->offline_waitq); } +/** + * cgroup_show_cftype - show or hide a cgroup file type + * @cft: cftype to show or hide + * @show: whether to show or hide + * + * Sets %CFTYPE_HIDDEN and shows/hides the matching files according to @show. + * @cft may or may not be added at the time of this call. After hiding, it's + * guaranteed that there are no in-flight operations on the hidden files. + */ +void cgroup_show_cftype(struct cftype *cft, bool show) +{ + struct cgroup_subsys *ss = cft->ss; + struct cgroup *root = ss ? &ss->root->cgrp : &cgrp_dfl_root.cgrp; + struct cgroup_subsys_state *css; + + mutex_lock(&cgroup_mutex); + + if (show) + cft->flags &= ~CFTYPE_HIDDEN; + else + cft->flags |= CFTYPE_HIDDEN; + + if (!(cft->flags & __CFTYPE_ADDED)) + goto out_unlock; + + css_for_each_descendant_pre(css, cgroup_css(root, ss)) { + struct cgroup *cgrp = css->cgroup; + struct kernfs_node *kn; + + if (!(css->flags & CSS_VISIBLE)) + continue; + + if (cft->file_offset) { + struct cgroup_file *cfile = + (void *)css + cft->file_offset; + + kn = cfile_kn_get(cfile); + if (kn) { + kernfs_show(kn, cfile_visible(cfile)); + kernfs_put(kn); + } + } else { + char buf[CGROUP_FILE_NAME_MAX]; + + kn = kernfs_find_and_get(cgrp->kn, + cgroup_file_name(cgrp, cft, buf)); + if (kn) { + kernfs_show(kn, show); + kernfs_put(kn); + } + } + } + +out_unlock: + mutex_unlock(&cgroup_mutex); +} + /** * css_create - create a cgroup_subsys_state * @cgrp: the cgroup new css will be associated with