Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964848AbbLOKBN (ORCPT ); Tue, 15 Dec 2015 05:01:13 -0500 Received: from mga14.intel.com ([192.55.52.115]:6367 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933277AbbLOKBJ (ORCPT ); Tue, 15 Dec 2015 05:01:09 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,431,1444719600"; d="scan'208";a="13425024" Subject: Re: [PATCH] android: fix warning when releasing active sync point To: Dmitry Torokhov , Greg Kroah-Hartman References: <20151215012955.GA28277@dtor-ws> Cc: Sumit Semwal , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOl?= =?UTF-8?Q?g?= , Riley Andrews , Andrew Bresticker , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org From: Maarten Lankhorst Message-ID: <566FE4E1.2040005@linux.intel.com> Date: Tue, 15 Dec 2015 11:01:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <20151215012955.GA28277@dtor-ws> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2108 Lines: 38 Op 15-12-15 om 02:29 schreef Dmitry Torokhov: > Userspace can close the sync device while there are still active fence > points, in which case kernel produces the following warning: > > [ 43.853176] ------------[ cut here ]------------ > [ 43.857834] WARNING: CPU: 0 PID: 892 at /mnt/host/source/src/third_party/kernel/v3.18/drivers/staging/android/sync.c:439 android_fence_release+0x88/0x104() > [ 43.871741] CPU: 0 PID: 892 Comm: Binder_5 Tainted: G U 3.18.0-07661-g0550ce9 #1 > [ 43.880176] Hardware name: Google Tegra210 Smaug Rev 1+ (DT) > [ 43.885834] Call trace: > [ 43.888294] [] dump_backtrace+0x0/0x10c > [ 43.893697] [] show_stack+0x10/0x1c > [ 43.898756] [] dump_stack+0x74/0xb8 > [ 43.903814] [] warn_slowpath_common+0x84/0xb0 > [ 43.909736] [] warn_slowpath_null+0x14/0x20 > [ 43.915482] [] android_fence_release+0x84/0x104 > [ 43.921582] [] fence_release+0x104/0x134 > [ 43.927066] [] sync_fence_free+0x74/0x9c > [ 43.932552] [] sync_fence_release+0x34/0x48 > [ 43.938304] [] __fput+0x100/0x1b8 > [ 43.943185] [] ____fput+0x8/0x14 > [ 43.947982] [] task_work_run+0xb0/0xe4 > [ 43.953297] [] do_notify_resume+0x44/0x5c > [ 43.958867] ---[ end trace 5a2aa4027cc5d171 ]--- > > Let's fix it by introducing a new optional callback (disable_signaling) > to fence operations so that drivers can do proper clean ups when we > remove last callback for given fence. > > Reviewed-by: Andrew Bresticker > Signed-off-by: Dmitry Torokhov > NACK! There's no way to do this race free. The driver should hold a refcount until fence is signaled. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/