use another lock for hid operations

lib/plugins.py

@@ -307,6 +307,7 @@ class DeviceMgr(ThreadJob, PrintError):
         self.recognised_hardware = set()
         # For synchronization
         self.lock = threading.RLock()
+        self.hid_lock = threading.RLock()
         self.config = config
 
     def thread_jobs(self):
@@ -490,6 +491,7 @@ class DeviceMgr(ThreadJob, PrintError):
         # wallet libraries are not affected.
         import hid
         self.print_error("scanning devices...")
+        with self.hid_lock:
             hid_list = hid.enumerate(0, 0)
         # First see what's connected that we know about
         devices = []

plugins/trezor/plugin.py

@@ -136,6 +136,7 @@ class TrezorCompatiblePlugin(HW_PluginBase):
         assert self.main_thread != threading.current_thread()
         devmgr = self.device_manager()
         handler = keystore.handler
+        with devmgr.hid_lock:
             client = devmgr.client_for_keystore(self, handler, keystore, force_pair)
         # returns the client for a given keystore. can use xpub
         if client: