From patchwork Sun May 28 19:11:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 13257940 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 96B0AC7EE2C for ; Sun, 28 May 2023 19:36:38 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2651E10E114; Sun, 28 May 2023 19:36:36 +0000 (UTC) Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9A0EB10E10D for ; Sun, 28 May 2023 19:36:33 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id AC4FA61E2F; Sun, 28 May 2023 19:36:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4E7AC4339B; Sun, 28 May 2023 19:36:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685302592; bh=QQnnE4i3eL6R307oEqra6ayyV8n51uDN9f9ilv2MX+g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ik4lZE/es+uunosYTtui/ci1PrM3O3+vbrUZ3KCYKbP9OeVxGn0G8nhw1tQupKl8K BQPfYZj5QbM5XIDOntu+HIjp4MwEgV5BzcRedMt2nVsAqv15KzS9Gk3bIeKO+dsbQm ruBIu0UiKvDntrUiAiAsLKWWArrO9HFF2wfYFp9s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Subject: [PATCH 6.1 065/119] drm: fix drmm_mutex_init() Date: Sun, 28 May 2023 20:11:05 +0100 Message-Id: <20230528190837.647782960@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190835.386670951@linuxfoundation.org> References: <20230528190835.386670951@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Jocelyn Falempe , Sarah Walker , Greg Kroah-Hartman , Lucas De Marchi , patches@lists.linux.dev, dri-devel@lists.freedesktop.org, Stanislaw Gruszka , Boris Brezillon , Matthew Auld , Thomas Zimmermann , Daniel Vetter Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Matthew Auld commit c21f11d182c2180d8b90eaff84f574cfa845b250 upstream. In mutex_init() lockdep identifies a lock by defining a special static key for each lock class. However if we wrap the macro in a function, like in drmm_mutex_init(), we end up generating: int drmm_mutex_init(struct drm_device *dev, struct mutex *lock) { static struct lock_class_key __key; __mutex_init((lock), "lock", &__key); .... } The static __key here is what lockdep uses to identify the lock class, however since this is just a normal function the key here will be created once, where all callers then use the same key. In effect the mutex->depmap.key will be the same pointer for different drmm_mutex_init() callers. This then results in impossible lockdep splats since lockdep thinks completely unrelated locks are the same lock class. To fix this turn drmm_mutex_init() into a macro such that it generates a different "static struct lock_class_key __key" for each invocation, which looks to be inline with what mutex_init() wants. v2: - Revamp the commit message with clearer explanation of the issue. - Rather export __drmm_mutex_release() than static inline. Reported-by: Thomas Hellström Reported-by: Sarah Walker Fixes: e13f13e039dc ("drm: Add DRM-managed mutex_init()") Cc: Stanislaw Gruszka Cc: Boris Brezillon Cc: Thomas Zimmermann Cc: Jocelyn Falempe Cc: Daniel Vetter Cc: dri-devel@lists.freedesktop.org Signed-off-by: Matthew Auld Reviewed-by: Boris Brezillon Reviewed-by: Stanislaw Gruszka Reviewed-by: Lucas De Marchi Acked-by: Thomas Zimmermann Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20230519090733.489019-1-matthew.auld@intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_managed.c | 22 ++-------------------- include/drm/drm_managed.h | 18 +++++++++++++++++- 2 files changed, 19 insertions(+), 21 deletions(-) --- a/drivers/gpu/drm/drm_managed.c +++ b/drivers/gpu/drm/drm_managed.c @@ -264,28 +264,10 @@ void drmm_kfree(struct drm_device *dev, } EXPORT_SYMBOL(drmm_kfree); -static void drmm_mutex_release(struct drm_device *dev, void *res) +void __drmm_mutex_release(struct drm_device *dev, void *res) { struct mutex *lock = res; mutex_destroy(lock); } - -/** - * drmm_mutex_init - &drm_device-managed mutex_init() - * @dev: DRM device - * @lock: lock to be initialized - * - * Returns: - * 0 on success, or a negative errno code otherwise. - * - * This is a &drm_device-managed version of mutex_init(). The initialized - * lock is automatically destroyed on the final drm_dev_put(). - */ -int drmm_mutex_init(struct drm_device *dev, struct mutex *lock) -{ - mutex_init(lock); - - return drmm_add_action_or_reset(dev, drmm_mutex_release, lock); -} -EXPORT_SYMBOL(drmm_mutex_init); +EXPORT_SYMBOL(__drmm_mutex_release); --- a/include/drm/drm_managed.h +++ b/include/drm/drm_managed.h @@ -105,6 +105,22 @@ char *drmm_kstrdup(struct drm_device *de void drmm_kfree(struct drm_device *dev, void *data); -int drmm_mutex_init(struct drm_device *dev, struct mutex *lock); +void __drmm_mutex_release(struct drm_device *dev, void *res); + +/** + * drmm_mutex_init - &drm_device-managed mutex_init() + * @dev: DRM device + * @lock: lock to be initialized + * + * Returns: + * 0 on success, or a negative errno code otherwise. + * + * This is a &drm_device-managed version of mutex_init(). The initialized + * lock is automatically destroyed on the final drm_dev_put(). + */ +#define drmm_mutex_init(dev, lock) ({ \ + mutex_init(lock); \ + drmm_add_action_or_reset(dev, __drmm_mutex_release, lock); \ +}) \ #endif