From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756506AbaDPTVm (ORCPT ); Wed, 16 Apr 2014 15:21:42 -0400 Received: from mail1.windriver.com ([147.11.146.13]:50768 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756187AbaDPTVi (ORCPT ); Wed, 16 Apr 2014 15:21:38 -0400 Message-ID: <534ED833.6020303@windriver.com> Date: Wed, 16 Apr 2014 15:21:23 -0400 From: Paul Gortmaker User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Stanislav Meduna , , "linux-kernel@vger.kernel.org" , "linux-rt-users@vger.kernel.org" Subject: Re: w1-gpio: sleeping function called from invalid context References: <534E97C8.5090407@meduna.org> In-Reply-To: <534E97C8.5090407@meduna.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [128.224.56.57] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14-04-16 10:46 AM, Stanislav Meduna wrote: > Hi, > > trying 1-wire with rt-patched Linux 3.12.15-rt25+ and lock debugging: I didn't have 3.12-rt handy, but looking at vanilla 3.12, I see that w1_touch_bit() turned off irqs via: static int w1_disable_irqs = 0; module_param_named(disable_irqs, w1_disable_irqs, int, 0); ... static void w1_write_bit(struct w1_master *dev, int bit) { unsigned long flags = 0; if(w1_disable_irqs) local_irq_save(flags); ... so, if you are using the above module parameter, it will do the below because gpiod_direction_output() does spin_lock_irqsave(&gpio_lock, flags); i.e. note it is not a raw lock, so it calls might_sleep, and then you get the unravel below. I've no idea why that module parameter exists. Why do you set it? Paul. -- > > [ 12.055550] BUG: sleeping function called from invalid context at /home/stano/Kernels/linux-3.12-rt/kernel/rtmutex.c:673 > [ 12.055573] in_atomic(): 0, irqs_disabled(): 128, pid: 92, name: w1_bus_master1 > [ 12.055588] 2 locks held by w1_bus_master1/92: > [ 12.055675] #0: (&dev->mutex){+.+...}, at: [] w1_process+0xbc/0xe0 > [ 12.055729] #1: (&dev->bus_mutex){+.+...}, at: [] w1_search+0x78/0x1e8 > [ 12.055741] irq event stamp: 374 > [ 12.055787] hardirqs last enabled at (373): [] _raw_spin_unlock_irqrestore+0x6c/0x74 > [ 12.055815] hardirqs last disabled at (374): [] w1_touch_bit+0x50/0xc4 > [ 12.055860] softirqs last enabled at (0): [] copy_process+0x37c/0x1178 > [ 12.055876] softirqs last disabled at (0): [< (null)>] (null) > [ 12.055899] CPU: 0 PID: 92 Comm: w1_bus_master1 Not tainted 3.12.15-rt25+ #66 > [ 12.055973] [] (unwind_backtrace+0x0/0xf4) from [] (show_stack+0x10/0x14) > [ 12.056020] [] (show_stack+0x10/0x14) from [] (rt_spin_lock+0x20/0x60) > [ 12.056080] [] (rt_spin_lock+0x20/0x60) from [] (gpiod_direction_output+0x50/0x2fc) > [ 12.056122] [] (gpiod_direction_output+0x50/0x2fc) from [] (w1_touch_bit+0x64/0xc4) > [ 12.056156] [] (w1_touch_bit+0x64/0xc4) from [] (w1_write_8+0x54/0x7c) > [ 12.056196] [] (w1_write_8+0x54/0x7c) from [] (w1_search+0xa0/0x1e8) > [ 12.056239] [] (w1_search+0xa0/0x1e8) from [] (w1_search_process_cb+0x50/0xe0) > [ 12.056280] [] (w1_search_process_cb+0x50/0xe0) from [] (w1_process+0xcc/0xe0) > [ 12.056334] [] (w1_process+0xcc/0xe0) from [] (kthread+0xa0/0xa8) > [ 12.056379] [] (kthread+0xa0/0xa8) from [] (ret_from_fork+0x14/0x34) > > This happens reproducibly on any access. > > Please Cc: me when replying > > Thanks >