From patchwork Mon May 2 08:40:51 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 8990571 Return-Path: X-Original-To: patchwork-dri-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 8BEEEBF29F for ; Mon, 2 May 2016 08:41:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6B50E20225 for ; Mon, 2 May 2016 08:41:19 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id F026120211 for ; Mon, 2 May 2016 08:41:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 006606E551; Mon, 2 May 2016 08:41:17 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail-wm0-x236.google.com (mail-wm0-x236.google.com [IPv6:2a00:1450:400c:c09::236]) by gabe.freedesktop.org (Postfix) with ESMTPS id 63D776E54F for ; Mon, 2 May 2016 08:41:14 +0000 (UTC) Received: by mail-wm0-x236.google.com with SMTP id a17so130970630wme.0 for ; Mon, 02 May 2016 01:41:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=bbWjBvK90erdUW4mW5zOb7aZv1RMVmJ1Ap+23XDuWCI=; b=DUmVevVibRR6s2ssXBC7kT2R51a4m2weprm9PO1zyJjhCq+mdURjYriJmYWeHv1gKn 7eK9UqVpv/MB5HyIo6GUWwXCuizecme7D40V3a/7O79kJdwlzzbvQZc0ZSKhy8GIK/5L H+dZYHJqWWDR7oST7iPuZvqMOBZgVFxGaH9XQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=bbWjBvK90erdUW4mW5zOb7aZv1RMVmJ1Ap+23XDuWCI=; b=HJ2R/bEZ3tmk0XCAtIW5Y08iy0iLrELh+FfIiVlqGcjbmCxjAhYBOk5Wmw9AjlxFVA 3lW7KIstFQ7YsJfs8xFULwbM/fLSu7rsAZoTrOT/C3QmCIRcd49M8pbgvnd/vL7Gg02A 5JDZA7ztFEOWZK2gm0jUvD6zXF5xb31FXvaqClNLsZfdRtjy3UWo6M62NgG3ElgVG8dP rApqcObgzCUrQ5FJImsZbn9Tv0johfd5BS0xbjO2DB51kcS/gBp2Nxyb7QYLhAGmtvWA 7WddMrQMwx+KKv25ljRSCSVRC07cOQkQCGp/Bruv3uLW7fUlFpGi9JS2nIpqZYH7kZtf ZiYQ== X-Gm-Message-State: AOPr4FUjtExZ4w7O+q79ps00JlOMy1h6htlQ8/hljwiE6TufWPBba2F+hz5A9Zvv+8H0bQ== X-Received: by 10.194.140.17 with SMTP id rc17mr40046732wjb.175.1462178472936; Mon, 02 May 2016 01:41:12 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:56b5:0:ac27:b86c:7764:9429]) by smtp.gmail.com with ESMTPSA id r8sm17607555wme.14.2016.05.02.01.41.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 May 2016 01:41:12 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH] drm/gem: support BO freeing without dev->struct_mutex Date: Mon, 2 May 2016 10:40:51 +0200 Message-Id: <1462178451-1765-1-git-send-email-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1461922299-12296-1-git-send-email-daniel.vetter@ffwll.ch> References: <1461922299-12296-1-git-send-email-daniel.vetter@ffwll.ch> Cc: Daniel Vetter , Intel Graphics Development , Daniel Vetter X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Spam-Status: No, score=-5.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Finally all the core gem and a lot of drivers are entirely free of dev->struct_mutex depencies, and we can start to have an entirely lockless unref path. To make sure that no one who touches the core code accidentally breaks existing drivers which still require dev->struct_mutex I've made the might_lock check unconditional. While at it de-inline the ref/unref functions, they've become a bit too big. v2: Make it not leak like a sieve. v3: Review from Lucas: - drop != NULL in pointer checks. - fixup copypasted kerneldoc to actually match the functions. v4: Add __drm_gem_object_unreference as a fastpath helper for drivers who abolished dev->struct_mutex, requested by Chris. v5: Fix silly mistake in drm_gem_object_unreference_unlocked caught by intel-gfx CI - I checked for gem_free_object instead of gem_free_object_unlocked ... Cc: Chris Wilson Cc: Alex Deucher Cc: Lucas Stach Reviewed-by: Lucas Stach (v3) Reviewed-by: Chris Wilson (v4) Signed-off-by: Daniel Vetter Reviewed-by: Alex Deucher --- drivers/gpu/drm/drm_gem.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++- include/drm/drmP.h | 15 ++++++++++--- include/drm/drm_gem.h | 48 +++++++++++++---------------------------- 3 files changed, 80 insertions(+), 37 deletions(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 25dac31eef37..973eb8805ce0 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -806,12 +806,64 @@ drm_gem_object_free(struct kref *kref) WARN_ON(!mutex_is_locked(&dev->struct_mutex)); - if (dev->driver->gem_free_object != NULL) + if (dev->driver->gem_free_object_unlocked) + dev->driver->gem_free_object_unlocked(obj); + else if (dev->driver->gem_free_object) dev->driver->gem_free_object(obj); } EXPORT_SYMBOL(drm_gem_object_free); /** + * drm_gem_object_unreference_unlocked - release a GEM BO reference + * @obj: GEM buffer object + * + * This releases a reference to @obj. Callers must not hold the + * dev->struct_mutex lock when calling this function. + * + * See also __drm_gem_object_unreference(). + */ +void +drm_gem_object_unreference_unlocked(struct drm_gem_object *obj) +{ + struct drm_device *dev; + + if (!obj) + return; + + dev = obj->dev; + might_lock(&dev->struct_mutex); + + if (dev->driver->gem_free_object_unlocked) + kref_put(&obj->refcount, drm_gem_object_free); + else if (kref_put_mutex(&obj->refcount, drm_gem_object_free, + &dev->struct_mutex)) + mutex_unlock(&dev->struct_mutex); +} +EXPORT_SYMBOL(drm_gem_object_unreference_unlocked); + +/** + * drm_gem_object_unreference - release a GEM BO reference + * @obj: GEM buffer object + * + * This releases a reference to @obj. Callers must hold the dev->struct_mutex + * lock when calling this function, even when the driver doesn't use + * dev->struct_mutex for anything. + * + * For drivers not encumbered with legacy locking use + * drm_gem_object_unreference_unlocked() instead. + */ +void +drm_gem_object_unreference(struct drm_gem_object *obj) +{ + if (obj) { + WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex)); + + kref_put(&obj->refcount, drm_gem_object_free); + } +} +EXPORT_SYMBOL(drm_gem_object_unreference); + +/** * drm_gem_vm_open - vma->ops->open implementation for GEM * @vma: VM area structure * diff --git a/include/drm/drmP.h b/include/drm/drmP.h index c81dd2250fc6..bd7b262d7af0 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -580,12 +580,21 @@ struct drm_driver { void (*debugfs_cleanup)(struct drm_minor *minor); /** - * Driver-specific constructor for drm_gem_objects, to set up - * obj->driver_private. + * @gem_free_object: deconstructor for drm_gem_objects * - * Returns 0 on success. + * This is deprecated and should not be used by new drivers. Use + * @gem_free_object_unlocked instead. */ void (*gem_free_object) (struct drm_gem_object *obj); + + /** + * @gem_free_object_unlocked: deconstructor for drm_gem_objects + * + * This is for drivers which are not encumbered with dev->struct_mutex + * legacy locking schemes. Use this hook instead of @gem_free_object. + */ + void (*gem_free_object_unlocked) (struct drm_gem_object *obj); + int (*gem_open_object) (struct drm_gem_object *, struct drm_file *); void (*gem_close_object) (struct drm_gem_object *, struct drm_file *); diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 0b3e11ab8757..408d6c47d98b 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -200,47 +200,29 @@ drm_gem_object_reference(struct drm_gem_object *obj) } /** - * drm_gem_object_unreference - release a GEM BO reference + * __drm_gem_object_unreference - raw function to release a GEM BO reference * @obj: GEM buffer object * - * This releases a reference to @obj. Callers must hold the dev->struct_mutex - * lock when calling this function, even when the driver doesn't use - * dev->struct_mutex for anything. + * This function is meant to be used by drivers which are not encumbered with + * dev->struct_mutex legacy locking and which are using the + * gem_free_object_unlocked callback. It avoids all the locking checks and + * locking overhead of drm_gem_object_unreference() and + * drm_gem_object_unreference_unlocked(). * - * For drivers not encumbered with legacy locking use - * drm_gem_object_unreference_unlocked() instead. + * Drivers should never call this directly in their code. Instead they should + * wrap it up into a driver_gem_object_unreference(struct driver_gem_object + * *obj) wrapper function, and use that. Shared code should never call this, to + * avoid breaking drivers by accident which still depend upon dev->struct_mutex + * locking. */ static inline void -drm_gem_object_unreference(struct drm_gem_object *obj) +__drm_gem_object_unreference(struct drm_gem_object *obj) { - if (obj != NULL) { - WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex)); - - kref_put(&obj->refcount, drm_gem_object_free); - } + kref_put(&obj->refcount, drm_gem_object_free); } -/** - * drm_gem_object_unreference_unlocked - release a GEM BO reference - * @obj: GEM buffer object - * - * This releases a reference to @obj. Callers must not hold the - * dev->struct_mutex lock when calling this function. - */ -static inline void -drm_gem_object_unreference_unlocked(struct drm_gem_object *obj) -{ - struct drm_device *dev; - - if (!obj) - return; - - dev = obj->dev; - if (kref_put_mutex(&obj->refcount, drm_gem_object_free, &dev->struct_mutex)) - mutex_unlock(&dev->struct_mutex); - else - might_lock(&dev->struct_mutex); -} +void drm_gem_object_unreference_unlocked(struct drm_gem_object *obj); +void drm_gem_object_unreference(struct drm_gem_object *obj); int drm_gem_handle_create(struct drm_file *file_priv, struct drm_gem_object *obj,