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) Reported-by: Sean Nyekjaer <sean.nyekjaer@xxxxxxxxx> Fixes: 9e6f4ca3e567 ("sc16is7xx: use kthread_worker for tx_work and irq") Cc: stable@xxxxxxxxxxxxxxx # v4.1+ Signed-off-by: Josh Cartwright <joshc@xxxxxx> --- 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 e78fa99..1bb5c0e 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1257,7 +1257,7 @@ 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; -- 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html