Commit a733ded5 authored Mar 05, 2017 by Tomas Winkler Committed by Greg Kroah-Hartman Mar 16, 2017

mei: fix deadlock on mei reset



This patch fixes 'mei: synchronize irq before initiating a reset'
The patch had introduced a deadlock between irq thread and mei_reset()
as they are both holding the same device lock.

---> device_lock:
	mei_reset()
                        <---- interrupt thread
	                        device_lock
---> synchornize_irq()
       wait on interrupt thread == (dead lock)

The fix is to call synchronize_irq
prior to call locked mei_reset function.

Cc: <stable@vger.kernel.org> #4.10+
Fixes: f302bb0de6ac (mei: synchronize irq before initiating a reset)
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 603980ce

drivers/misc/mei/init.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -124,8 +124,6 @@ int mei_reset(struct mei_device *dev)

		mei_clear_interrupts(dev);

		mei_synchronize_irq(dev);

		/* we're already in reset, cancel the init timer
		* if the reset was called due the hbm protocol error
		* we need to call it before hw start
		@@ -304,6 +302,9 @@ static void mei_reset_work(struct work_struct *work)
		container_of(work, struct mei_device, reset_work);
		int ret;

		mei_clear_interrupts(dev);
		mei_synchronize_irq(dev);

		mutex_lock(&dev->device_lock);

		ret = mei_reset(dev);
		@@ -328,6 +329,9 @@ void mei_stop(struct mei_device *dev)

		mei_cancel_work(dev);

		mei_clear_interrupts(dev);
		mei_synchronize_irq(dev);

		mutex_lock(&dev->device_lock);

		dev->dev_state = MEI_DEV_POWER_DOWN;

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