From patchwork Sat Nov 11 02:47:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 13452912 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80B00539C for ; Sat, 11 Nov 2023 02:48:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="O+jiY3TF" Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22E9B3C15; Fri, 10 Nov 2023 18:48:57 -0800 (PST) Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-6b1d1099a84so2721372b3a.1; Fri, 10 Nov 2023 18:48:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1699670936; x=1700275736; darn=vger.kernel.org; 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=047RScGgMjhfhvkeVSqTgX+A9EaMBWDmBq31ySPa+B0=; b=O+jiY3TFnZrwNUsQ2sOpDv0XttRsKbZDX6WUQnF1eYbv56lIa5InU7jeylczt02leP OMn/+KuhU/ja2eUs22nywaoDmRXRqWdVZoDTIOjOHhwHRbjg7r3SkxAbdEP2onwiojwI 5gY74lKKoJjiY5MauXai+Y74TJfMkZwhCjcjYSWhvfYoNKx0xU+s5n9UkTiRxtqGq15o eaKd5mEdCxsjHgai6Z03ATSVCEweEUutB6pGQmQ60SXD8ELUIb0nez3ms6B2hN3LgLqN htMYxVPVlGlTORZjOkMjrK9o1Llo39vfmRwvQl2zmb5vG0wyWNjVCGDwDTpUXhfdVXTh y0IQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699670936; x=1700275736; 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=047RScGgMjhfhvkeVSqTgX+A9EaMBWDmBq31ySPa+B0=; b=o6KO1UrZtyUZiXr1d/m3VY6pYQnYRxzAvN9ON1Saqo+GyVlGYOLcdchQRsnuvXJWaz 4iRLWt1RtuzBQp0svJCtt80Qs+7tLCdF/7zo1kj9AAk4F7VNa+xHei2AITV1j/Pcyt79 0fBj+rBxwooF5RTqWhrsMeKM28FSUeCk3w7zEejOer5OvnQ6vxDDhQYE/ndrTnyP/Gyx XhAwoj38wF4WxZtqCika97td6Rj0jr54nb8BfBQ5X3pNLU4EFO2PJQMZyrfjrnJnHSmi YXcP1GqO45MipxQCquU02Pq/wr+sM2srL1mSAdsy1HYzgcPrWGsRZS0XBdhORKUgzvlH sR9A== X-Gm-Message-State: AOJu0Yy1wNv/KgdSiSCm7QrIG+X9cGMbX2gS4uAnaNB8t7rQNZtIAorx Z8Q5Pu9Pw7LEXRQueChk8SU= X-Google-Smtp-Source: AGHT+IHQLCJahNyA+ScLSn5pPMMwd9BjDvwBNhTkSwF7/JXPfbg14Sz/EvG6j536DODoFObhzAajQw== X-Received: by 2002:a05:6a00:10c8:b0:6b8:a6d6:f51a with SMTP id d8-20020a056a0010c800b006b8a6d6f51amr925662pfu.31.1699670936344; Fri, 10 Nov 2023 18:48:56 -0800 (PST) Received: from localhost ([2620:10d:c090:400::4:7384]) by smtp.gmail.com with ESMTPSA id e14-20020a62ee0e000000b00688435a9915sm382537pfi.189.2023.11.10.18.48.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Nov 2023 18:48:55 -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, changwoo@igalia.com, himadrics@inria.fr, memxor@gmail.com Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kernel-team@meta.com, Tejun Heo Subject: [PATCH 01/36] cgroup: Implement cgroup_show_cftypes() Date: Fri, 10 Nov 2023 16:47:27 -1000 Message-ID: <20231111024835.2164816-2-tj@kernel.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231111024835.2164816-1-tj@kernel.org> References: <20231111024835.2164816-1-tj@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 265da00a1a8b..6194d7c13573 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 0ef0af66080e..d164eaeacfa6 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -113,6 +113,7 @@ 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 484adb375b15..d00fa84edd4c 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4210,10 +4210,13 @@ 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; @@ -4489,6 +4492,24 @@ 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 @@ -4498,15 +4519,20 @@ 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); } /** @@ -5534,6 +5560,63 @@ 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