From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE860C1B0F1 for ; Wed, 20 Jun 2018 00:30:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B06BA20693 for ; Wed, 20 Jun 2018 00:30:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B06BA20693 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754311AbeFTAax (ORCPT ); Tue, 19 Jun 2018 20:30:53 -0400 Received: from terminus.zytor.com ([198.137.202.136]:52471 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752807AbeFTAau (ORCPT ); Tue, 19 Jun 2018 20:30:50 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w5K0Uj2g3300257 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 19 Jun 2018 17:30:45 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w5K0UjbP3300254; Tue, 19 Jun 2018 17:30:45 -0700 Date: Tue, 19 Jun 2018 17:30:45 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Reinette Chatre Message-ID: Cc: hpa@zytor.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, mingo@kernel.org, reinette.chatre@intel.com Reply-To: reinette.chatre@intel.com, mingo@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@zytor.com In-Reply-To: <1200798a50791186cd959d75aa3145409ca5151a.1527593971.git.reinette.chatre@intel.com> References: <1200798a50791186cd959d75aa3145409ca5151a.1527593971.git.reinette.chatre@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/cache] x86/intel_rdt: Create resctrl debug area Git-Commit-ID: b880ab2702eb426b2fcebce315a22f1b19003aa9 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b880ab2702eb426b2fcebce315a22f1b19003aa9 Gitweb: https://git.kernel.org/tip/b880ab2702eb426b2fcebce315a22f1b19003aa9 Author: Reinette Chatre AuthorDate: Tue, 29 May 2018 05:57:58 -0700 Committer: Thomas Gleixner CommitDate: Wed, 20 Jun 2018 00:56:38 +0200 x86/intel_rdt: Create resctrl debug area In preparation for support of debugging of RDT sub features the user can now enable a RDT debugfs region. The debug area is always enabled when CONFIG_DEBUG_FS is set as advised in http://lkml.kernel.org/r/20180523080501.GA6822@kroah.com Also from same discussion in above linked email, no error checking on the debugfs creation return value since code should not behave differently when debugging passes or fails. Even on failure the returned value can be passed safely to other debugfs calls. Signed-off-by: Reinette Chatre Signed-off-by: Thomas Gleixner Cc: fenghua.yu@intel.com Cc: tony.luck@intel.com Cc: vikas.shivappa@linux.intel.com Cc: gavin.hindman@intel.com Cc: jithu.joseph@intel.com Cc: dave.hansen@intel.com Cc: hpa@zytor.com Link: https://lkml.kernel.org/r/1200798a50791186cd959d75aa3145409ca5151a.1527593971.git.reinette.chatre@intel.com --- arch/x86/kernel/cpu/intel_rdt.h | 2 ++ arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 27 +++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h index c948266d59c8..bd3050c1ab6c 100644 --- a/arch/x86/kernel/cpu/intel_rdt.h +++ b/arch/x86/kernel/cpu/intel_rdt.h @@ -432,6 +432,8 @@ extern struct rdt_resource rdt_resources_all[]; extern struct rdtgroup rdtgroup_default; DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key); +extern struct dentry *debugfs_resctrl; + enum { RDT_RESOURCE_L3, RDT_RESOURCE_L3DATA, diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index 89ac02f91238..68c8d3654e05 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -22,6 +22,7 @@ #include #include +#include #include #include #include @@ -56,6 +57,8 @@ static struct kernfs_node *kn_mondata; static struct seq_buf last_cmd_status; static char last_cmd_status_buf[512]; +struct dentry *debugfs_resctrl; + void rdt_last_cmd_clear(void) { lockdep_assert_held(&rdtgroup_mutex); @@ -2811,6 +2814,29 @@ int __init rdtgroup_init(void) if (ret) goto cleanup_mountpoint; + /* + * Adding the resctrl debugfs directory here may not be ideal since + * it would let the resctrl debugfs directory appear on the debugfs + * filesystem before the resctrl filesystem is mounted. + * It may also be ok since that would enable debugging of RDT before + * resctrl is mounted. + * The reason why the debugfs directory is created here and not in + * rdt_mount() is because rdt_mount() takes rdtgroup_mutex and + * during the debugfs directory creation also &sb->s_type->i_mutex_key + * (the lockdep class of inode->i_rwsem). Other filesystem + * interactions (eg. SyS_getdents) have the lock ordering: + * &sb->s_type->i_mutex_key --> &mm->mmap_sem + * During mmap(), called with &mm->mmap_sem, the rdtgroup_mutex + * is taken, thus creating dependency: + * &mm->mmap_sem --> rdtgroup_mutex for the latter that can cause + * issues considering the other two lock dependencies. + * By creating the debugfs directory here we avoid a dependency + * that may cause deadlock (even though file operations cannot + * occur until the filesystem is mounted, but I do not know how to + * tell lockdep that). + */ + debugfs_resctrl = debugfs_create_dir("resctrl", NULL); + return 0; cleanup_mountpoint: @@ -2823,6 +2849,7 @@ cleanup_root: void __exit rdtgroup_exit(void) { + debugfs_remove_recursive(debugfs_resctrl); unregister_filesystem(&rdt_fs_type); sysfs_remove_mount_point(fs_kobj, "resctrl"); kernfs_destroy_root(rdt_root);