| Subject: sc16is7xx: Drop bogus use of IRQF_ONESHOT |
| From: Josh Cartwright <joshc@ni.com> |
| Date: Thu, 18 Feb 2016 11:26:12 -0600 |
| |
| 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 <sean.nyekjaer@prevas.dk> |
| Signed-off-by: Josh Cartwright <joshc@ni.com> |
| Cc: linux-rt-users@vger.kernel.org |
| Cc: Jakub Kicinski <moorray3@wp.pl> |
| 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 <tglx@linutronix.de> |
| --- |
| 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 |
| @@ -1251,7 +1251,7 @@ 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; |
| |