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SubjectRe: [PATCH] sc16is7xx: drop bogus use of IRQF_ONESHOT
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On 2016-02-18 18:26, Josh Cartwright wrote:
> 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@prevas.dk>
> Fixes: 9e6f4ca3e567 ("sc16is7xx: use kthread_worker for tx_work and irq")
> Cc: stable@vger.kernel.org # v4.1+
> Signed-off-by: Josh Cartwright <joshc@ni.com>
> ---
> 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;
>
Is PATCH this dropped?
It clearly fixes the irq when running with RT patches :-)

/Sean

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