Subject: sc16is7xx: Drop bogus use of IRQF_ONESHOT From: Josh Cartwright Date: Thu, 18 Feb 2016 11:26:12 -0600 Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.8/older/patches-4.8.14-rt9.tar.xz 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+0x18/0x74) queue_kthread_work) from (sc16is7xx_irq+0x10/0x18 [sc16is7xx]) sc16is7xx_irq [sc16is7xx]) from (handle_irq_event_percpu+0x70/0x158) handle_irq_event_percpu) from (handle_irq_event+0x68/0xa8) handle_irq_event) from (handle_level_irq+0x10c/0x184) handle_level_irq) from (generic_handle_irq+0x2c/0x3c) generic_handle_irq) from (mxc_gpio_irq_handler+0x3c/0x108) mxc_gpio_irq_handler) from (mx3_gpio_irq_handler+0x80/0xcc) mx3_gpio_irq_handler) from (generic_handle_irq+0x2c/0x3c) generic_handle_irq) from (__handle_domain_irq+0x7c/0xe8) __handle_domain_irq) from (gic_handle_irq+0x24/0x5c) gic_handle_irq) from (__irq_svc+0x40/0x88) (__irq_svc) from (rt_spin_unlock+0x1c/0x68) (rt_spin_unlock) from (kthread_worker_fn+0x104/0x17c) (kthread_worker_fn) from (kthread+0xd0/0xe8) (kthread) from (ret_from_fork+0x14/0x2c) 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 Link: http://lkml.kernel.org/r/1455816372-13989-1-git-send-email-joshc@ni.com Signed-off-by: Thomas Gleixner --- 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;