From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH 00/25] tty: serial: drop uart_port->lock before calling Date: Mon, 19 Aug 2013 09:15:59 -0400 Message-ID: <52121A8F.8050600@hurleysoftware.com> References: <20130816122753.GA24550@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout39.mail01.mtsvc.net ([216.70.64.83]:38453 "EHLO n12.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751412Ab3HSNQH (ORCPT ); Mon, 19 Aug 2013 09:16:07 -0400 In-Reply-To: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Viresh Kumar Cc: Greg KH , jslaby@suse.cz, Lists linaro-kernel , Patch Tracking , linux-serial@vger.kernel.org, Bryan Huntsman , Daniel Walker , David Brown , Stephen Warren , Tobias Klauser , Tony Prisk On 08/19/2013 06:43 AM, Viresh Kumar wrote: > On 16 August 2013 23:14, Viresh Kumar wrote: >> On 16 August 2013 17:57, Greg KH wrote: > >>> Lots of tty and serial changes have happened since -rc5 in linux-next, >>> can you please rebase, and test, these against that tree and resend them >>> if they are still needed? >> >> I have rebased them over latest linux-next and they applied cleanly.. >> Haven't tested it though.. Will try that next week. > > I initially thought that the problem only occurs with a merge to RT > kernel otherwise this would have happened to lots of people.. > > But when I tried latest linux-next/master (as of today), without > RT patch I was able to reproduce the issue on Samsung's Arndale > board. > > [ 129.179314] [] (unwind_backtrace+0x0/0xf8) from [] (show_stack+0x10/0x14) > [ 129.187676] [] (show_stack+0x10/0x14) from [] (dump_stack+0x6c/0xac) > [ 129.195619] [] (dump_stack+0x6c/0xac) from [] (do_raw_spin_unlock+0xc4/0xd8) > [ 129.204247] [] (do_raw_spin_unlock+0xc4/0xd8) from [] (_raw_spin_unlock_irqrestore+0xc/0) > [ 129.214241] [] (_raw_spin_unlock_irqrestore+0xc/0x38) from [] (s3c24xx_serial_rx_chars+0) > [ 129.224832] [] (s3c24xx_serial_rx_chars+0x12c/0x260) from [] (s3c64xx_serial_handle_irq+) > [ 129.235336] [] (s3c64xx_serial_handle_irq+0x48/0x60) from [] (handle_irq_event_percpu+0x) > [ 129.245753] [] (handle_irq_event_percpu+0x50/0x194) from [] (handle_irq_event+0x3c/0x5c) > [ 129.255407] [] (handle_irq_event+0x3c/0x5c) from [] (handle_fasteoi_irq+0x80/0x13c) > [ 129.264636] [] (handle_fasteoi_irq+0x80/0x13c) from [] (generic_handle_irq+0x20/0x30) > [ 129.274030] [] (generic_handle_irq+0x20/0x30) from [] (handle_IRQ+0x38/0x94) > [ 129.282655] [] (handle_IRQ+0x38/0x94) from [] (gic_handle_irq+0x34/0x68) > [ 129.290938] [] (gic_handle_irq+0x34/0x68) from [] (__irq_svc+0x40/0x70) > [ 129.299134] Exception stack(0xc04cdf70 to 0xc04cdfb8) > [ 129.304084] df60: 00000000 00000000 0000166e 00000000 > [ 129.312117] df80: c04cc000 c050278f c050278f 00000001 c04d444c 410fc0f4 c03649b0 00000000 > [ 129.320146] dfa0: 00000001 c04cdfb8 c000f758 c000f75c 60070013 ffffffff > [ 129.326639] [] (__irq_svc+0x40/0x70) from [] (arch_cpu_idle+0x28/0x30) > [ 129.334756] [] (arch_cpu_idle+0x28/0x30) from [] (cpu_startup_entry+0x5c/0x148) > [ 129.343644] [] (cpu_startup_entry+0x5c/0x148) from [] (start_kernel+0x334/0x38c) > [ 133.343767] BUG: spinlock lockup suspected on CPU#0, kworker/0:1/360 > [ 133.348574] lock: s3c24xx_serial_ports+0x1d8/0x370, .magic: dead4ead, .owner: /-1, .owner_cpu: -1 > [ 133.357885] CPU: 0 PID: 360 Comm: kworker/0:1 Not tainted 3.11.0-rc6-next-20130819-00003-g75485f1 #2 > [ 133.366858] Workqueue: events flush_to_ldisc > [ 133.371034] [] (unwind_backtrace+0x0/0xf8) from [] (show_stack+0x10/0x14) > [ 133.379413] [] (show_stack+0x10/0x14) from [] (dump_stack+0x6c/0xac) > [ 133.387355] [] (dump_stack+0x6c/0xac) from [] (do_raw_spin_lock+0x100/0x17c) > [ 133.395982] [] (do_raw_spin_lock+0x100/0x17c) from [] (_raw_spin_lock_irqsave+0x20/0x28) > [ 133.405635] [] (_raw_spin_lock_irqsave+0x20/0x28) from [] (uart_start+0x18/0x34) > [ 133.414602] [] (uart_start+0x18/0x34) from [] (__receive_buf+0x4b4/0x738) > [ 133.422973] [] (__receive_buf+0x4b4/0x738) from [] (n_tty_receive_buf2+0x30/0x98) > [ 133.432026] [] (n_tty_receive_buf2+0x30/0x98) from [] (flush_to_ldisc+0xec/0x138) > [ 133.441081] [] (flush_to_ldisc+0xec/0x138) from [] (process_one_work+0xfc/0x348) > [ 133.450048] [] (process_one_work+0xfc/0x348) from [] (worker_thread+0x138/0x37c) > [ 133.459014] [] (worker_thread+0x138/0x37c) from [] (kthread+0xa4/0xb0) > [ 133.467128] [] (kthread+0xa4/0xb0) from [] (ret_from_fork+0x14/0x3c) > > > And so yes they are required over latest linux-next as well.. > I will resend V2 soon. Thanks.. Umm. How did a worker thread schedule while an IRQ handler was holding a irq-disabling spin lock? Regards, Peter Hurley PS - please paste your stack backtraces with line-wrap disabled