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Commit e728ae27 authored by Alexander Usyskin's avatar Alexander Usyskin Committed by Greg Kroah-Hartman
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mei: amthif: fix deadlock in initialization during a reset 



The device lock was unnecessary obtained in bus rescan work before the
amthif client search.  That causes incorrect lock ordering and task
hang:
...
[88004.613213] INFO: task kworker/1:14:21832 blocked for more than 120 seconds.
...
[88004.645934] Workqueue: events mei_cl_bus_rescan_work
...

The correct lock order is
 cl_bus_lock
  device_lock
   me_clients_rwsem

Move device_lock into amthif init function that called
after me_clients_rwsem is released.

This fixes regression introduced by commit:
commit 025fb792 ("mei: split amthif client init from end of clients enumeration")

Cc: <stable@vger.kernel.org> # 4.6+
Signed-off-by: default avatarAlexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: default avatarTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 80293c47

drivers/misc/mei/amthif.c

+9 −3
Original line number Diff line number Diff line
@@ -66,8 +66,12 @@ int mei_amthif_host_init(struct mei_device *dev, struct mei_me_client *me_cl) 
	struct mei_cl *cl = &dev->iamthif_cl;

	int ret;



	if (mei_cl_is_connected(cl))

		return 0;

	mutex_lock(&dev->device_lock);



	if (mei_cl_is_connected(cl)) {

		ret = 0;

		goto out;

	}



	dev->iamthif_state = MEI_IAMTHIF_IDLE;
@@ -76,11 +80,13 @@ int mei_amthif_host_init(struct mei_device *dev, struct mei_me_client *me_cl) 
	ret = mei_cl_link(cl);

	if (ret < 0) {

		dev_err(dev->dev, "amthif: failed cl_link %d\n", ret);

		return ret;

		goto out;

	}



	ret = mei_cl_connect(cl, me_cl, NULL);



out:

	mutex_unlock(&dev->device_lock);

	return ret;

}

drivers/misc/mei/bus.c

+0 −2
Original line number Diff line number Diff line
@@ -984,12 +984,10 @@ void mei_cl_bus_rescan_work(struct work_struct *work) 
		container_of(work, struct mei_device, bus_rescan_work);

	struct mei_me_client *me_cl;



	mutex_lock(&bus->device_lock);

	me_cl = mei_me_cl_by_uuid(bus, &mei_amthif_guid);

	if (me_cl)

		mei_amthif_host_init(bus, me_cl);

	mei_me_cl_put(me_cl);

	mutex_unlock(&bus->device_lock);



	mei_cl_bus_rescan(bus);

}