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 be9b720a0ccb ("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>

3 files changed, 2 insertions, 19 deletions

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 357b6ae4d207..458aa5a09c52 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -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);
diff --git a/drivers/misc/mei/init.c b/drivers/misc/mei/init.c
index 94514b2c7a50..00c3865ca3b1 100644
--- a/drivers/misc/mei/init.c
+++ b/drivers/misc/mei/init.c
@@ -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);
diff --git a/drivers/misc/mei/nfc.c b/drivers/misc/mei/nfc.c
index b983c4ecad38..290ef3037437 100644
--- a/drivers/misc/mei/nfc.c
+++ b/drivers/misc/mei/nfc.c
@@ -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);
 }