From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.8 54/96] sc16is7xx: Drop bogus use of IRQF_ONESHOT Date: Fri, 6 Jan 2017 22:43:42 +0100 Message-ID: <20170106214229.903947950@linuxfoundation.org> References: <20170106214227.601120243@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20170106214227.601120243@linuxfoundation.org> Sender: linux-rt-users-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Nyekjaer , Josh Cartwright , linux-rt-users@vger.kernel.org, Jakub Kicinski , linux-serial@vger.kernel.org, Sebastian Andrzej Siewior , Julia Cartwright , Jakub Kicinski List-Id: linux-serial@vger.kernel.org 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Cartwright commit 04da73803c05dc1150ccc31cbf93e8cd56679c09 upstream. 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: linux-serial@vger.kernel.org Cc: Sebastian Andrzej Siewior Signed-off-by: Julia Cartwright Acked-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sc16is7xx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1240,7 +1240,7 @@ static int sc16is7xx_probe(struct device /* 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;