From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753817AbcHPP2C (ORCPT ); Tue, 16 Aug 2016 11:28:02 -0400 Received: from www381.your-server.de ([78.46.137.84]:59259 "EHLO www381.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750864AbcHPP17 (ORCPT ); Tue, 16 Aug 2016 11:27:59 -0400 Subject: Re: [PATCH v2] iio: fix sched WARNING "do not call blocking ops when !TASK_RUNNING" To: Jonathan Cameron , Brian Norris References: <20160802011244.GA54171@google.com> <37ea974c-9ac6-5a40-0f0e-ee34ef605a08@metafoo.de> <20160802165732.GA3310@localhost> <9a6a7f54-0343-db74-57a2-9f747ae659cc@metafoo.de> <20160804082621.GA11331@localhost> <20160809001937.GA23658@google.com> Cc: Hartmut Knaack , Peter Meerwald-Stadler , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck , Brian Norris , Peter Zijlstra , Ingo Molnar From: Lars-Peter Clausen Message-ID: Date: Tue, 16 Aug 2016 17:27:53 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Authenticated-Sender: lars@metafoo.de Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/15/2016 05:54 PM, Jonathan Cameron wrote: > On 09/08/16 01:19, Brian Norris wrote: >> When using CONFIG_DEBUG_ATOMIC_SLEEP, the scheduler nicely points out >> that we're calling sleeping primitives within the wait_event loop, which >> means we might clobber the task state: >> >> [ 10.831289] do not call blocking ops when !TASK_RUNNING; state=1 set at [] >> [ 10.845531] ------------[ cut here ]------------ >> [ 10.850161] WARNING: at kernel/sched/core.c:7630 >> ... >> [ 12.164333] ---[ end trace 45409966a9a76438 ]--- >> [ 12.168942] Call trace: >> [ 12.171391] [] __might_sleep+0x64/0x90 >> [ 12.176699] [] mutex_lock_nested+0x50/0x3fc >> [ 12.182440] [] iio_kfifo_buf_data_available+0x28/0x4c >> [ 12.189043] [] iio_buffer_ready+0x60/0xe0 >> [ 12.194608] [] iio_buffer_read_first_n_outer+0x108/0x1a8 >> [ 12.201474] [] __vfs_read+0x58/0x114 >> [ 12.206606] [] vfs_read+0x94/0x118 >> [ 12.211564] [] SyS_read+0x64/0xb4 >> [ 12.216436] [] el0_svc_naked+0x24/0x28 >> >> To avoid this, we should (a la https://lwn.net/Articles/628628/) use the >> wait_woken() function, which avoids the nested sleeping while still >> handling races between waiting / wake-events. >> >> Signed-off-by: Brian Norris > Looks good to me, but given Lars' involvement in the discussion I'd > like his review before applying this. Looks good. Thanks Brian for fixing this. Reviewed-by: Lars-Peter Clausen