Commit d78006d2 authored by Josh Cartwright's avatar Josh Cartwright Committed by Greg Kroah-Hartman

sc16is7xx: Drop bogus use of IRQF_ONESHOT

commit 04da7380 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: 9e6f4ca3 ("sc16is7xx: use kthread_worker for tx_work and irq")
Reported-by: default avatarSean Nyekjaer <sean.nyekjaer@prevas.dk>
Signed-off-by: default avatarJosh Cartwright <joshc@ni.com>
Cc: linux-rt-users@vger.kernel.org
Cc: Jakub Kicinski <moorray3@wp.pl>
Cc: linux-serial@vger.kernel.org
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarJulia Cartwright <julia@ni.com>
Acked-by: default avatarJakub Kicinski <kubakici@wp.pl>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b988320d
......@@ -1230,7 +1230,7 @@ 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;
......
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