rt-patches/0305-sc16is7xx-Drop-bogus-use-of-IRQF_ONESHOT.patch

   1 From 50a03d3fbfe4bf1db18c4fc78c63b023a3372f69 Mon Sep 17 00:00:00 2001
   2 From: Josh Cartwright <joshc@ni.com>
   3 Date: Thu, 18 Feb 2016 11:26:12 -0600
   4 Subject: [PATCH 305/365] sc16is7xx: Drop bogus use of IRQF_ONESHOT
   5
   6 The use of IRQF_ONESHOT when registering an interrupt handler with
   7 request_irq() is non-sensical.
   8
   9 Not only that, it also prevents the handler from being threaded when it
  10 otherwise should be w/ IRQ_FORCED_THREADING is enabled.  This causes the
  11 following deadlock observed by Sean Nyekjaer on -rt:
  12
  13 Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
  14 [..]
  15    rt_spin_lock_slowlock from (queue_kthread_work+0x18/0x74)
  16    queue_kthread_work) from (sc16is7xx_irq+0x10/0x18 [sc16is7xx])
  17    sc16is7xx_irq [sc16is7xx]) from (handle_irq_event_percpu+0x70/0x158)
  18    handle_irq_event_percpu) from (handle_irq_event+0x68/0xa8)
  19    handle_irq_event) from (handle_level_irq+0x10c/0x184)
  20    handle_level_irq) from (generic_handle_irq+0x2c/0x3c)
  21    generic_handle_irq) from (mxc_gpio_irq_handler+0x3c/0x108)
  22    mxc_gpio_irq_handler) from (mx3_gpio_irq_handler+0x80/0xcc)
  23    mx3_gpio_irq_handler) from (generic_handle_irq+0x2c/0x3c)
  24    generic_handle_irq) from (__handle_domain_irq+0x7c/0xe8)
  25    __handle_domain_irq) from (gic_handle_irq+0x24/0x5c)
  26    gic_handle_irq) from (__irq_svc+0x40/0x88)
  27    (__irq_svc) from (rt_spin_unlock+0x1c/0x68)
  28    (rt_spin_unlock) from (kthread_worker_fn+0x104/0x17c)
  29    (kthread_worker_fn) from (kthread+0xd0/0xe8)
  30    (kthread) from (ret_from_fork+0x14/0x2c)
  31
  32 Fixes: 9e6f4ca3e567 ("sc16is7xx: use kthread_worker for tx_work and irq")
  33 Reported-by: Sean Nyekjaer <sean.nyekjaer@prevas.dk>
  34 Signed-off-by: Josh Cartwright <joshc@ni.com>
  35 Cc: linux-rt-users@vger.kernel.org
  36 Cc: Jakub Kicinski <moorray3@wp.pl>
  37 Cc: stable@vger.kernel.org
  38 Cc: linux-serial@vger.kernel.org
  39 Link: http://lkml.kernel.org/r/1455816372-13989-1-git-send-email-joshc@ni.com
  40 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  41 ---
  42  drivers/tty/serial/sc16is7xx.c | 2 +-
  43  1 file changed, 1 insertion(+), 1 deletion(-)
  44
  45 diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
  46 index cc86c34..ac51f0d 100644
  47 --- a/drivers/tty/serial/sc16is7xx.c
  48 +++ b/drivers/tty/serial/sc16is7xx.c
  49 @@ -1230,7 +1230,7 @@ static int sc16is7xx_probe(struct device *dev,
  50
  51         /* Setup interrupt */
  52         ret = devm_request_irq(dev, irq, sc16is7xx_irq,
  53 -                              IRQF_ONESHOT | flags, dev_name(dev), s);
  54 +                              flags, dev_name(dev), s);
  55         if (!ret)
  56                 return 0;
  57
  58 --
  59 2.7.4
  60