From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) (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 39F53363 for ; Tue, 26 Apr 2022 04:23:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650947006; x=1682483006; h=subject:from:to:cc:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RPsTBLRj1KMYFKyyD8tLYZbU16tTm3/UP+mPjNuhPJk=; b=JXVbVJpdn/jXS/I+zsBqxILnP3oG9/KDLxlXvkVNRx2aUQBE5jg8J+M7 Deg1bZVVoNaeGWqmXxbpBS4jhMIwFbd+yM/yOYyjwVsVy0EAb4Q6ZLWjN SxtiGKDMZp1rrLvF+/3g+2iwHNXTliwi3/hzXzUPx4Nu+KFqPeR4W/tXE lQSuLY5asdGcyONx3UV8QTWnAHNMPeKZ0bdCgBwRjEommVR/tdqROkdU9 hRJBe1FVv+JaE/A836MI8tbz7eyPntBpT/9ecep4NGVfCvoL+nsDr2TIt NYIPgZJAAAB3wahICdZqFgibUxc6H/TOkeCaNm9h9Apcj4aFFJ2ThI0aW Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10328"; a="290588842" X-IronPort-AV: E=Sophos;i="5.90,290,1643702400"; d="scan'208";a="290588842" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Apr 2022 21:23:25 -0700 X-IronPort-AV: E=Sophos;i="5.90,290,1643702400"; d="scan'208";a="564391541" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.25]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Apr 2022 21:23:25 -0700 Subject: [PATCH v5 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: Mon, 25 Apr 2022 21:23:25 -0700 Message-ID: <165094691930.1127280.7077256361741497990.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <165074768280.4047093.15803516065715087623.stgit@dwillia2-desk3.amr.corp.intel.com> References: <165074768280.4047093.15803516065715087623.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-3-g996c Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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, however device_set_lock_class() still needs #ifdef CONFIG_PROVE_LOCKING since lockdep_match_class() explicitly does not have a helper in the CONFIG_PROVE_LOCKING=n case (see comment in lockdep.h). The lockdep API needs 2 small tweaks to prevent "unused" warnings for the @key argument to lock_set_class(), and a new lock_set_novalidate_class() is added to supplement lockdep_set_novalidate_class() in the cases where the lock class is converted while the lock is held. 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 v4: - Rather than attempt to error out when device_set_lock_class() is overriding an existing lock class, just WARN and revisit if it becomes a problem. (Peter). drivers/cxl/acpi.c | 13 +++++++++++++ include/linux/device.h | 43 +++++++++++++++++++++++++++++++++++++++++++ include/linux/lockdep.h | 6 +++++- 3 files changed, 61 insertions(+), 1 deletion(-) diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c index d15a6aec0331..40286f5df812 100644 --- a/drivers/cxl/acpi.c +++ b/drivers/cxl/acpi.c @@ -275,6 +275,13 @@ 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) +{ + device_lock_reset_class(dev); +} + static int cxl_acpi_probe(struct platform_device *pdev) { int rc; @@ -283,6 +290,12 @@ 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..355127d0de78 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -850,6 +850,49 @@ 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) \ +do { \ + struct device *__d __maybe_unused = dev; \ + lock_set_class(&__d->mutex.dep_map, name, key, 0, _THIS_IP_); \ +} while (0) + +/** + * 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. + */ +#ifdef CONFIG_LOCKDEP +#define device_lock_set_class(dev, key) \ +do { \ + struct device *__d = dev; \ + dev_WARN_ONCE(__d, !lockdep_match_class(&__d->mutex, \ + &__lockdep_no_validate__), \ + "overriding existing custom lock class\n"); \ + __device_lock_set_class(__d, #key, key); \ +} while (0) +#else +#define device_lock_set_class(dev, key) __device_lock_set_class(dev, #key, key) +#endif + +/** + * 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) \ +do { \ + struct device *__d __maybe_unused = dev; \ + lock_set_novalidate_class(&__d->mutex.dep_map, "&dev->mutex", \ + _THIS_IP_); \ +} while (0) + void lock_device_hotplug(void); void unlock_device_hotplug(void); int lock_device_hotplug_sysfs(void); diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 467b94257105..43b0dc6a0b21 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -290,6 +290,9 @@ extern void lock_set_class(struct lockdep_map *lock, const char *name, struct lock_class_key *key, unsigned int subclass, unsigned long ip); +#define lock_set_novalidate_class(l, n, i) \ + lock_set_class(l, n, &__lockdep_no_validate__, 0, i) + static inline void lock_set_subclass(struct lockdep_map *lock, unsigned int subclass, unsigned long ip) { @@ -357,7 +360,8 @@ static inline void lockdep_set_selftest_task(struct task_struct *task) # define lock_acquire(l, s, t, r, c, n, i) do { } while (0) # define lock_release(l, i) do { } while (0) # define lock_downgrade(l, i) do { } while (0) -# define lock_set_class(l, n, k, s, i) do { } while (0) +# define lock_set_class(l, n, key, s, i) do { (void)(key); } while (0) +# define lock_set_novalidate_class(l, n, i) do { } while (0) # define lock_set_subclass(l, s, i) do { } while (0) # define lockdep_init() do { } while (0) # define lockdep_init_map_type(lock, name, key, sub, inner, outer, type) \