From patchwork Tue Jun 30 09:06:27 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Lukas Wunner X-Patchwork-Id: 7482591 Return-Path: X-Original-To: patchwork-intel-gfx@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 E10AABF90C for ; Sun, 25 Oct 2015 13:59:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A71942074A for ; Sun, 25 Oct 2015 13:59:40 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 94E5A2063E for ; Sun, 25 Oct 2015 13:59:39 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A88CC6E27F; Sun, 25 Oct 2015 06:59:38 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mailout2.hostsharing.net (mailout2.hostsharing.net [83.223.90.233]) by gabe.freedesktop.org (Postfix) with ESMTPS id 584BC6E27F for ; Sun, 25 Oct 2015 06:59:36 -0700 (PDT) Received: from h08.hostsharing.net (h08.hostsharing.net [83.223.95.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mailout2.hostsharing.net (Postfix) with ESMTPS id 1190810189B97; Sun, 25 Oct 2015 14:59:35 +0100 (CET) Received: from localhost (6-38-90-81.adsl.cmo.de [81.90.38.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by h08.hostsharing.net (Postfix) with ESMTPSA id C8375605E00B; Sun, 25 Oct 2015 14:59:32 +0100 (CET) X-Mailbox-Line: From 4a4f691ea23a9a3f84afc47928c81e681cfd6fc7 Mon Sep 17 00:00:00 2001 Message-Id: <4a4f691ea23a9a3f84afc47928c81e681cfd6fc7.1445771693.git.lukas@wunner.de> In-Reply-To: References: <20151015173423.GK26517@intel.com> From: Lukas Wunner Date: Tue, 30 Jun 2015 10:06:27 +0100 MIME-Version: 1.0 To: intel-gfx@lists.freedesktop.org Subject: [Intel-gfx] [PATCH v6 3/4] drm/i915: Fix failure paths around initial fbdev allocation X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00, DATE_IN_PAST_96_XX, RCVD_IN_DNSWL_MED,RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=ham 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 From: Tvrtko Ursulin We had two failure modes here: 1. Deadlock in intelfb_alloc failure path where it calls drm_framebuffer_remove, which grabs the struct mutex and intelfb_create (caller of intelfb_alloc) was already holding it. 2. Deadlock in intelfb_create failure path where it calls drm_framebuffer_unreference, which grabs the struct mutex and intelfb_create was already holding it. [Chris Wilson on why struct_mutex needs to be locked in the second half of intelfb_create: "there is a bug here where we don't take an explicit pin on the VMA we setup for the fbdev which requires the lock."] v2: * Reformat commit msg to 72 chars. (Lukas Wunner) * Add third failure mode. (Lukas Wunner) v5: * Rebase on drm-intel-nightly 2015y-09m-01d-09h-06m-08s UTC, rephrase commit message. (Jani Nicula) v6: * In intelfb_alloc, if __intel_framebuffer_create failed, fb will be an ERR_PTR, thus not null. So in the failure path we need to check for IS_ERR_OR_NULL to avoid calling drm_framebuffer_remove on the ERR_PTR. (Lukas Wunner) * Since this is init code a drm_framebuffer_unreference should be all we need. drm_framebuffer_remove is for framebuffers that userspace has created - and is getting somewhat defeatured. (Daniel Vetter) Signed-off-by: Tvrtko Ursulin Fixes: 60a5ca015ffd ("drm/i915: Add locking around framebuffer_references--") Reported-by: Lukas Wunner [Lukas: Create v3 + v4 + v5 + v6 based on Tvrtko's v2] Signed-off-by: Lukas Wunner Cc: Chris Wilson Cc: Ville Syrjälä Reviewed-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_fbdev.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c index ec82b51..12597b5 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -119,7 +119,7 @@ static int intelfb_alloc(struct drm_fb_helper *helper, { struct intel_fbdev *ifbdev = container_of(helper, struct intel_fbdev, helper); - struct drm_framebuffer *fb; + struct drm_framebuffer *fb = NULL; struct drm_device *dev = helper->dev; struct drm_i915_private *dev_priv = to_i915(dev); struct drm_mode_fb_cmd2 mode_cmd = {}; @@ -138,6 +138,8 @@ static int intelfb_alloc(struct drm_fb_helper *helper, mode_cmd.pixel_format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth); + mutex_lock(&dev->struct_mutex); + size = mode_cmd.pitches[0] * mode_cmd.height; size = PAGE_ALIGN(size); @@ -165,16 +167,19 @@ static int intelfb_alloc(struct drm_fb_helper *helper, ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL, NULL, NULL); if (ret) { DRM_ERROR("failed to pin obj: %d\n", ret); - goto out_fb; + goto out; } + mutex_unlock(&dev->struct_mutex); + ifbdev->fb = to_intel_framebuffer(fb); return 0; -out_fb: - drm_framebuffer_remove(fb); out: + mutex_unlock(&dev->struct_mutex); + if (!IS_ERR_OR_NULL(fb)) + drm_framebuffer_unreference(fb); return ret; } @@ -192,8 +197,6 @@ static int intelfb_create(struct drm_fb_helper *helper, int size, ret; bool prealloc = false; - mutex_lock(&dev->struct_mutex); - if (intel_fb && (sizes->fb_width > intel_fb->base.width || sizes->fb_height > intel_fb->base.height)) { @@ -208,7 +211,7 @@ static int intelfb_create(struct drm_fb_helper *helper, DRM_DEBUG_KMS("no BIOS fb, allocating a new one\n"); ret = intelfb_alloc(helper, sizes); if (ret) - goto out_unlock; + return ret; intel_fb = ifbdev->fb; } else { DRM_DEBUG_KMS("re-using BIOS fb\n"); @@ -220,6 +223,8 @@ static int intelfb_create(struct drm_fb_helper *helper, obj = intel_fb->obj; size = obj->base.size; + mutex_lock(&dev->struct_mutex); + info = drm_fb_helper_alloc_fbi(helper); if (IS_ERR(info)) { ret = PTR_ERR(info); @@ -281,7 +286,6 @@ out_destroy_fbi: out_unpin: i915_gem_object_ggtt_unpin(obj); drm_gem_object_unreference(&obj->base); -out_unlock: mutex_unlock(&dev->struct_mutex); return ret; }