[PATCH 4.8 54/96] sc16is7xx: Drop bogus use of IRQF_ONESHOT

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

--

From: Josh Cartwright 

commit 04da73803c05dc1150ccc31cbf93e8cd56679c09 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: 9e6f4ca3e567 ("sc16is7xx: use kthread_worker for tx_work and irq")
Reported-by: Sean Nyekjaer 
Signed-off-by: Josh Cartwright 
Cc: linux-rt-us...@vger.kernel.org
Cc: Jakub Kicinski 
Cc: linux-ser...@vger.kernel.org
Cc: Sebastian Andrzej Siewior 
Signed-off-by: Julia Cartwright 
Acked-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman 

---
 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;
 

[PATCH 4.8 54/96] sc16is7xx: Drop bogus use of IRQF_ONESHOT

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

--

From: Josh Cartwright 

commit 04da73803c05dc1150ccc31cbf93e8cd56679c09 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: 9e6f4ca3e567 ("sc16is7xx: use kthread_worker for tx_work and irq")
Reported-by: Sean Nyekjaer 
Signed-off-by: Josh Cartwright 
Cc: linux-rt-us...@vger.kernel.org
Cc: Jakub Kicinski 
Cc: linux-ser...@vger.kernel.org
Cc: Sebastian Andrzej Siewior 
Signed-off-by: Julia Cartwright 
Acked-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman 

---
 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;