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mei: nfc: fix deadlock on shutdown/suspend path 

In function mei_nfc_host_exit mei_cl_remove_device cannot be called
under the device mutex as device removing flow invokes the device driver
remove handler that calls in turn to mei_cl_disable_device which
naturally acquires the device mutex.

Also remove mei_cl_bus_remove_devices which has the same issue, but is
never executed as currently the only device on the mei client bus is NFC
and a new device cannot be easily added till the bus revamp is
completed.

This fixes regression caused by commit be9b720a0c ("mei_phy: move all
nfc logic from mei driver to nfc")

Prior to this change the nfc driver remove handler called to no-op
disable function while actual nfc device was disabled directly from the
mei driver.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tomas Winkler 2015-07-08 00:22:03 +03:00 committed by Linus Torvalds
parent c7e9ad7da2
commit 4f273959b8
3 changed files with 2 additions and 19 deletions
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16
drivers/misc/mei/bus.c
View File

@ -552,22 +552,6 @@ void mei_cl_bus_rx_event(struct mei_cl *cl)
schedule_work(&device->event_work);
}
void mei_cl_bus_remove_devices(struct mei_device *dev)
{
struct mei_cl *cl, *next;
mutex_lock(&dev->device_lock);
list_for_each_entry_safe(cl, next, &dev->device_list, device_link) {
if (cl->device)
mei_cl_remove_device(cl->device);
list_del(&cl->device_link);
mei_cl_unlink(cl);
kfree(cl);
}
mutex_unlock(&dev->device_lock);
}
int __init mei_cl_bus_init(void)
{
return bus_register(&mei_cl_bus_type);

2
drivers/misc/mei/init.c
View File

@ -333,8 +333,6 @@ void mei_stop(struct mei_device *dev)
mei_nfc_host_exit(dev);
mei_cl_bus_remove_devices(dev);
mutex_lock(&dev->device_lock);
mei_wd_stop(dev);

3
drivers/misc/mei/nfc.c
View File

@ -402,11 +402,12 @@ void mei_nfc_host_exit(struct mei_device *dev)
cldev->priv_data = NULL;
mutex_lock(&dev->device_lock);
/* Need to remove the device here
* since mei_nfc_free will unlink the clients
*/
mei_cl_remove_device(cldev);
mutex_lock(&dev->device_lock);
mei_nfc_free(ndev);
mutex_unlock(&dev->device_lock);
}