From patchwork Wed Dec 13 08:57:20 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Szyprowski X-Patchwork-Id: 10109519 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E2C07603ED for ; Wed, 13 Dec 2017 08:57:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D811A28BEF for ; Wed, 13 Dec 2017 08:57:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CCB9D28BF3; Wed, 13 Dec 2017 08:57:47 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4198528BF5 for ; Wed, 13 Dec 2017 08:57:46 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6A008898E8; Wed, 13 Dec 2017 08:57:44 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mailout1.w1.samsung.com (mailout1.w1.samsung.com [210.118.77.11]) by gabe.freedesktop.org (Postfix) with ESMTPS id 369F3898E8 for ; Wed, 13 Dec 2017 08:57:42 +0000 (UTC) Received: from eucas1p1.samsung.com (unknown [182.198.249.206]) by mailout1.w1.samsung.com (KnoxPortal) with ESMTP id 20171213085738euoutp011b2e15451d8c1a07f6b5a6172a2cb732~-zt9K2D-E1612616126euoutp01B; Wed, 13 Dec 2017 08:57:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.w1.samsung.com 20171213085738euoutp011b2e15451d8c1a07f6b5a6172a2cb732~-zt9K2D-E1612616126euoutp01B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1513155458; bh=dQRqWmmdLna+Zr1Y6o+J4dO25KRm52AiCs29QSJJ+IE=; h=From:To:Cc:Subject:Date:References:From; b=gAGEwo2Ucxm7wMlRTAKvlGdjWtlGAUNx5d/6LXqHShizrdkiFDI1ZD/3yJZ73a09T 0Kp3ORfRA+6Pxet4gW9sv6I+bPxo81/AMqi7yJYMQiQmAxStR5eZzg//S9BNlAerGD 8F/eClr1EQ6E605iqTfPvewbe8dDOCdeCJwA88rI= Received: from eusmges3.samsung.com (unknown [203.254.199.242]) by eucas1p1.samsung.com (KnoxPortal) with ESMTP id 20171213085737eucas1p199c40074cd67d656161fed6f0588bd93~-zt8cEjWV0128401284eucas1p1H; Wed, 13 Dec 2017 08:57:37 +0000 (GMT) Received: from eucas1p1.samsung.com ( [182.198.249.206]) by eusmges3.samsung.com (EUCPMTA) with SMTP id 97.56.12867.18BE03A5; Wed, 13 Dec 2017 08:57:37 +0000 (GMT) Received: from eusmgms1.samsung.com (unknown [182.198.249.179]) by eucas1p2.samsung.com (KnoxPortal) with ESMTP id 20171213085736eucas1p28d10718330c5c2eac834bd26786c84fc~-zt7wNHxX1622416224eucas1p2T; Wed, 13 Dec 2017 08:57:36 +0000 (GMT) X-AuditID: cbfec7f2-f793b6d000003243-42-5a30eb81e917 Received: from eusync2.samsung.com ( [203.254.199.212]) by eusmgms1.samsung.com (EUCPMTA) with SMTP id 80.0F.18832.08BE03A5; Wed, 13 Dec 2017 08:57:36 +0000 (GMT) Received: from AMDC2765.digital.local ([106.116.147.25]) by eusync2.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTPA id <0P0W00EQ267W1Y60@eusync2.samsung.com>; Wed, 13 Dec 2017 08:57:36 +0000 (GMT) From: Marek Szyprowski To: dri-devel@lists.freedesktop.org, Daniel Vetter , Jani Nikula , Gustavo Padovan , Sean Paul , David Airlie Subject: [PATCH] drm: Fix possible deadlock in drm_mode_config_cleanup() Date: Wed, 13 Dec 2017 09:57:20 +0100 Message-id: <20171213085720.6059-1-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.15.0 X-Brightmail-Tracker: H4sIAAAAAAAAAzWSa0hTYRjHe8/Zzs6Gk+Mm+qKBsawPhanYh5cuZiD59iHoQkkjyVGHZTqT HRWNILs4bVqKYI6krG0qLC+xhjmzVXbRWa4sEbNmq0lpNhUvmUmR7sxvv//z/z/P/8tDkzKz MILOyM5ltdmqLAUlEbS9XHTFXJiIU8ZVtEvQVZeTQNVfRinU+LqFRAPzUxRq+tgF0CVTK4V+ zphIZPd0iFDj+1aABpcMFFossRHI6h0UIsMbB4Gan7tFyDmsB8h9rw+g6rlpAfpjmAboWvM7 KkmOp4aKRbi2qF+A291mgJ113yj8t7aYxKbOcQJbLVco/Gmwk8IPfnmE+JbzAH58s0mEP5d1 E/i++Ty2VbhF2F71iMDXbBawP0Qp2XGSzcrIZ7WxiemSU0O/64Q5xsgC+7ADFIGecD0Q05DZ CqdH9YDnMPh2pJXSAwktY+oBdBqMAl7MAtj49S5Y3ahtKAG80QBgzbAlkCoioHfMQq2kKCYe 6n16/61QZgxAa5POL0jmqQAOlFcSKyk5g+H33j7hCguYDVB/vZlcYSmzA87aDYG+KGhasPuX IWMUwbEBXcBIhhPGMoJnOfzRbRPxvBZeKX0amFcAeLF4M88GAF0+Kc/b4bPufn8xyQTDqraa 5WJ6eS6FpToZjxj6Snbx6d2w5bPXf1HGpMFqWydVCSJugzUWEMrmcRo1yyVs4VQaLi9bveXE GY0VLP/Oq3/dM+1gvmdbF2BooAiSejyxSplQlc8VaroApElFqLT8eJxSJj2pKjzLas8c1+Zl sVwXiKQFinDpTqXuqIxRq3LZTJbNYbWrLkGLI4rAwb0bneVkfcrSafG3HHVKuVS5SXi47+u+ 7PmHsb1h/6LN1yWXHWmHgofSaiYTc5YmHLoYc2rBkaD00ZT14rfrJh+NX1o4ptvjfRFUteiJ viO6mxs5Mr83qvLGnFBdYPyQkPkkGXBqydFCzTk57XI8ngzNrGto3hWS2mH1zaQlSRQC7pQq fhOp5VT/ARuqxs03AwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrPLMWRmVeSWpSXmKPExsVy+t/xK7oNrw2iDI63aVn0njvJZDH14RM2 i+Vn1jFbXPn6ns1ize1DjBbNi9ezWbz5tJjZYueDXewWyy+vZ7S49nsGm8XP9i1MFpseX2O1 mHF+H5PF2iN32S1O3upitLi74SyjxdQvH1gsfs34wGjRt/YSm4Owx/sbrewesxsusnjsuLuE 0ePk/GdsHn9ntzJ7LN7zkslj06pONo871/aweWz/9oDVY97JQI/9c9ewe9zvPs7ksXlJvceW /rvsHjsn7WXy6NuyijFAMIrLJiU1J7MstUjfLoEr48aP+awFi6Qrdt7ax9jAeEK8i5GTQ0LA RGL2snZGCFtM4sK99WxdjFwcQgJLGCVuzf0P5TQxSVz6sJEVpIpNwFCi620XWEJE4AWjxNNb B1lAHGaBoywS65uPs4NUCQt4SDw/dRasg0VAVaJr2lpmEJtXwEbi884ZUPvkJRZ/38k2gZF7 ASPDKkaR1NLi3PTcYkO94sTc4tK8dL3k/NxNjMBo2Hbs5+YdjJc2Bh9iFOBgVOLhffBAP0qI NbGsuDL3EKMEB7OSCG9PvEGUEG9KYmVValF+fFFpTmrxIUZpDhYlcd7ePasjhQTSE0tSs1NT C1KLYLJMHJxSDYwJ580nM4iuW3hftHhRdOuNh223RJ9s+pfcq+N0qn39rIfXdBa9PumtK7Sh RP9E057j63cG+HVP3tX270bpI7nGb46tZz0Xm1r+fHhq4x8zpRiN00ZnAlwk+JdobnQodl10 98mn8nz1qV6LPwuqPz5+7NG5+iNf30a/Xr23UExxh1FCyY8/z5W6lViKMxINtZiLihMBY+XG 6IICAAA= X-CMS-MailID: 20171213085736eucas1p28d10718330c5c2eac834bd26786c84fc X-Msg-Generator: CA CMS-TYPE: 201P X-CMS-RootMailID: 20171213085736eucas1p28d10718330c5c2eac834bd26786c84fc X-RootMTR: 20171213085736eucas1p28d10718330c5c2eac834bd26786c84fc References: Cc: linux-samsung-soc@vger.kernel.org, Tomeu Vizoso , Greg Kroah-Hartman , Kevin Hilman , Thierry Escande , Shuah Khan , Mark Brown , Matt Hart , Guillaume Tucker , Enric Balletbo i Serra , Javier Martinez Canillas , linux-arm-kernel@lists.infradead.org, Marek Szyprowski 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-Virus-Scanned: ClamAV using ClamSMTP drm_mode_config_cleanup() might be called from a workqueue context (for example in error path handling of deferred probe), so it must not call flush_scheduled_work(), because it would deadlock in such case. Replace that call with explicit counting of the scheduled connector free works and waiting until it reaches zero. Fixes: a703c55004e1 ("drm: safely free connectors from connector_iter") Signed-off-by: Marek Szyprowski --- This fixes the issue discussed in the following thread: https://www.spinics.net/lists/arm-kernel/msg622332.html --- drivers/gpu/drm/drm_connector.c | 6 +++++- drivers/gpu/drm/drm_mode_config.c | 6 +++++- include/drm/drm_mode_config.h | 13 +++++++++++++ 3 files changed, 23 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index 0b7e0974e6da..7620ac1ad1b1 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -161,6 +161,8 @@ static void drm_connector_free_work_fn(struct work_struct *work) drm_mode_object_unregister(dev, &connector->base); connector->funcs->destroy(connector); + atomic_dec(&dev->mode_config.connector_free_works); + wake_up_all(&dev->mode_config.connector_free_queue); } /** @@ -552,8 +554,10 @@ EXPORT_SYMBOL(drm_connector_list_iter_begin); static void drm_connector_put_safe(struct drm_connector *conn) { - if (refcount_dec_and_test(&conn->base.refcount.refcount)) + if (refcount_dec_and_test(&conn->base.refcount.refcount)) { + atomic_inc(&conn->dev->mode_config.connector_free_works); schedule_work(&conn->free_work); + } } /** diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index 6ffe952142e6..cca443faebd8 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -381,6 +381,7 @@ void drm_mode_config_init(struct drm_device *dev) idr_init(&dev->mode_config.tile_idr); ida_init(&dev->mode_config.connector_ida); spin_lock_init(&dev->mode_config.connector_list_lock); + init_waitqueue_head(&dev->mode_config.connector_free_queue); drm_mode_create_standard_properties(dev); @@ -431,8 +432,11 @@ void drm_mode_config_cleanup(struct drm_device *dev) drm_connector_put(connector); } drm_connector_list_iter_end(&conn_iter); + /* connector_iter drops references in a work item. */ - flush_scheduled_work(); + wait_event(dev->mode_config.connector_free_queue, + !atomic_read(&dev->mode_config.connector_free_works)); + if (WARN_ON(!list_empty(&dev->mode_config.connector_list))) { drm_connector_list_iter_begin(dev, &conn_iter); drm_for_each_connector_iter(connector, &conn_iter) diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index a0afeb591dcb..83a7db997e83 100644 --- a/include/drm/drm_mode_config.h +++ b/include/drm/drm_mode_config.h @@ -413,6 +413,19 @@ struct drm_mode_config { * &struct drm_connector_list_iter to walk this list. */ struct list_head connector_list; + /** + * @pending_connector_free_works: + * + * Number of scheduled connector->free_work instances, see + * drm_connector_put_safe(). + */ + atomic_t connector_free_works; + /** + * @pending_connector_free_queue: + * + * Wait queue for waiting until connector->free_work is finished. + */ + wait_queue_head_t connector_free_queue; /** * @num_encoder: *