From patchwork Sat Apr 23 21:05:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 12824683 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 C0FFEC433EF for ; Sat, 23 Apr 2022 21:05:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237073AbiDWVIV (ORCPT ); Sat, 23 Apr 2022 17:08:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232418AbiDWVIT (ORCPT ); Sat, 23 Apr 2022 17:08:19 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E0EAD54 for ; Sat, 23 Apr 2022 14:05:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650747920; x=1682283920; h=subject:from:to:cc:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=u2uujpIWafLuqRQHmmYfUJuJS1w46wzg590lAQIVpiY=; b=fVjWlD88vU5A71tdX1LRrnVjcDunY/jaiBIA7byYwQK2yvnSresTG33x bqx6T5TyEjnzbieIqWkRhjE4y81ZJy0pqX0CsLfQRnmkKbnmUVA65bfWv /M3+r41AOCSDAjrfgsx0slRoDHQzfA0xZtNoxHJB6yy1jxblzWu7W3DsD tO7uZ4dqc8uhz2h1QLi2thmsH8pnr0rhMyoE0Jo9lLzNRhKN1d03ZjhqA jDFJGQh82YIa0wTr7ZEHdOB2bdIjX45zean83kqm5n8wzUAWF83f+jhy+ feo8y7udJA2h18WhbSsFM5IhyTuueKuKqApC3RZdoIjeRh/12/VeBUhPo A==; X-IronPort-AV: E=McAfee;i="6400,9594,10326"; a="290088252" X-IronPort-AV: E=Sophos;i="5.90,285,1643702400"; d="scan'208";a="290088252" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2022 14:05:20 -0700 X-IronPort-AV: E=Sophos;i="5.90,285,1643702400"; d="scan'208";a="729057744" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.25]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2022 14:05:20 -0700 Subject: [PATCH v4 2/8] cxl/acpi: Add root device lockdep validation From: Dan Williams To: linux-cxl@vger.kernel.org Cc: Peter Zijlstra , "Rafael J. Wysocki" , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng , Alison Schofield , Vishal Verma , Ben Widawsky , Jonathan Cameron , Greg Kroah-Hartman , Ira Weiny , nvdimm@lists.linux.dev Date: Sat, 23 Apr 2022 14:05:20 -0700 Message-ID: <165074768280.4047093.15803516065715087623.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <165055519869.3745911.10162603933337340370.stgit@dwillia2-desk3.amr.corp.intel.com> References: <165055519869.3745911.10162603933337340370.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org The CXL "root" device, ACPI0017, is an attach point for coordinating platform level CXL resources and is the parent device for a CXL port topology tree. As such it has distinct locking rules relative to other CXL subsystem objects, but because it is an ACPI device the lock class is established well before it is given to the cxl_acpi driver. However, the lockdep API does support changing the lock class "live" for situations like this. Add a device_lock_set_class() helper that a driver can use in ->probe() to set a custom lock class, and device_lock_reset_class() to return to the default "no validate" class before the custom lock class key goes out of scope after ->remove(). Note the helpers are all macros to support dead code elimination in the CONFIG_PROVE_LOCKING=n case. Suggested-by: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: Alison Schofield Cc: Vishal Verma Cc: Ben Widawsky Cc: Jonathan Cameron Reviewed-by: Greg Kroah-Hartman Reviewed-by: Ira Weiny Signed-off-by: Dan Williams --- Changes since v3: - Add a comment about expected usage of device_lock_set_class() to only override the "no validate" class (Ira) - Clang-format the macros - Fix device_lock_reset_class() to reset the lock class name to "&dev->mutex". drivers/cxl/acpi.c | 15 +++++++++++++++ include/linux/device.h | 25 +++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index d15a6aec0331..e19cea27387e 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -275,6 +275,15 @@ static int add_root_nvdimm_bridge(struct device *match, void *data) return 1; } +static struct lock_class_key cxl_root_key; + +static void cxl_acpi_lock_reset_class(void *_dev) +{ + struct device *dev = _dev; + + device_lock_reset_class(dev); +} + static int cxl_acpi_probe(struct platform_device *pdev) { int rc; @@ -283,6 +292,12 @@ static int cxl_acpi_probe(struct platform_device *pdev) struct acpi_device *adev = ACPI_COMPANION(host); struct cxl_cfmws_context ctx; + device_lock_set_class(&pdev->dev, &cxl_root_key); + rc = devm_add_action_or_reset(&pdev->dev, cxl_acpi_lock_reset_class, + &pdev->dev); + if (rc) + return rc; + root_port = devm_cxl_add_port(host, host, CXL_RESOURCE_NONE, NULL); if (IS_ERR(root_port)) return PTR_ERR(root_port); diff --git a/include/linux/device.h b/include/linux/device.h index 93459724dcde..a4a7c1bf3b72 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -850,6 +850,31 @@ static inline bool device_supports_offline(struct device *dev) return dev->bus && dev->bus->offline && dev->bus->online; } +#define __device_lock_set_class(dev, name, key) \ + lock_set_class(&(dev)->mutex.dep_map, name, key, 0, _THIS_IP_) + +/** + * device_lock_set_class - Specify a temporary lock class while a device + * is attached to a driver + * @dev: device to modify + * @key: lock class key data + * + * This must be called with the device_lock() already held, for example + * from driver ->probe(). Take care to only override the default + * lockdep_no_validate class. + */ +#define device_lock_set_class(dev, key) __device_lock_set_class(dev, #key, key) + +/** + * device_lock_reset_class - Return a device to the default lockdep novalidate state + * @dev: device to modify + * + * This must be called with the device_lock() already held, for example + * from driver ->remove(). + */ +#define device_lock_reset_class(dev) \ + __device_lock_set_class(dev, "&dev->mutex", &__lockdep_no_validate__) + void lock_device_hotplug(void); void unlock_device_hotplug(void); int lock_device_hotplug_sysfs(void);