Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752399AbcJCPO6 (ORCPT ); Mon, 3 Oct 2016 11:14:58 -0400 Received: from skprod3.natinst.com ([130.164.80.24]:56022 "EHLO ni.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750991AbcJCPOs (ORCPT ); Mon, 3 Oct 2016 11:14:48 -0400 From: Julia Cartwright To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Sean Nyekjaer , Josh Cartwright , linux-rt-users@vger.kernel.org, Jakub Kicinski , stable@vger.kernel.org, linux-serial@vger.kernel.org, Sebastian Andrzej Siewior Subject: [PATCH] sc16is7xx: Drop bogus use of IRQF_ONESHOT Date: Mon, 3 Oct 2016 10:14:32 -0500 Message-Id: <20161003151432.17828-1-julia@ni.com> X-Mailer: git-send-email 2.9.3 X-MIMETrack: Itemize by SMTP Server on US-AUS-MGWOut2/AUS/H/NIC(Release 8.5.3FP6 HF1218|December 12, 2014) at 10/03/2016 10:14:32 AM, Serialize by Router on US-AUS-MGWOut2/AUS/H/NIC(Release 8.5.3FP6 HF1218|December 12, 2014) at 10/03/2016 10:14:32 AM, Serialize complete at 10/03/2016 10:14:32 AM X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-10-03_09:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2180 Lines: 60 The use of IRQF_ONESHOT when registering an interrupt handler with request_irq() is non-sensical. Not only that, it also prevents the handler from being threaded when it otherwise should be w/ IRQ_FORCED_THREADING is enabled. This causes the following deadlock observed by Sean Nyekjaer on -rt: Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM [..] rt_spin_lock_slowlock from queue_kthread_work queue_kthread_work from sc16is7xx_irq sc16is7xx_irq [sc16is7xx] from handle_irq_event_percpu handle_irq_event_percpu from handle_irq_event handle_irq_event from handle_level_irq handle_level_irq from generic_handle_irq generic_handle_irq from mxc_gpio_irq_handler mxc_gpio_irq_handler from mx3_gpio_irq_handler mx3_gpio_irq_handler from generic_handle_irq generic_handle_irq from __handle_domain_irq __handle_domain_irq from gic_handle_irq gic_handle_irq from __irq_svc __irq_svc from rt_spin_unlock rt_spin_unlock from kthread_worker_fn kthread_worker_fn from kthread kthread from ret_from_fork Fixes: 9e6f4ca3e567 ("sc16is7xx: use kthread_worker for tx_work and irq") Reported-by: Sean Nyekjaer Signed-off-by: Josh Cartwright Cc: linux-rt-users@vger.kernel.org Cc: Jakub Kicinski Cc: stable@vger.kernel.org Cc: linux-serial@vger.kernel.org Cc: Sebastian Andrzej Siewior Signed-off-by: Julia Cartwright --- This patch has been in -rt for a little while, but it isn't -rt specific. See relevant bug report thread which starts here: http://www.spinics.net/lists/linux-rt-users/msg14620.html drivers/tty/serial/sc16is7xx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index a9d94f7..96a374d 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1260,7 +1260,7 @@ static int sc16is7xx_probe(struct device *dev, /* Setup interrupt */ ret = devm_request_irq(dev, irq, sc16is7xx_irq, - IRQF_ONESHOT | flags, dev_name(dev), s); + flags, dev_name(dev), s); if (!ret) return 0; -- 2.9.3