commit edbb73a411919af954619dcee02bc448912c9e27
author David Lechner <david@pybricks.com> Wed Jan 22 11:19:37 2020 -0600
committer Damien George <damien.p.george@gmail.com> Thu Jan 23 13:29:11 2020 +1100
tree b868fbd83601252ef3a7d43e6ad0ce155740355b
parent ccc18f047d6669583cdf8ddd53ec41d026743a25

py/qstr: Don't include or init qstr_mutex when GIL is enabled.

When threads and the GIL are enabled, then the qstr mutex is not needed.
The qstr_mutex field is never used in this case because of:

    #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
    #define QSTR_ENTER() mp_thread_mutex_lock(&MP_STATE_VM(qstr_mutex), 1)
    #define QSTR_EXIT() mp_thread_mutex_unlock(&MP_STATE_VM(qstr_mutex))
    #else
    #define QSTR_ENTER()
    #define QSTR_EXIT()
    #endif

So, we can completely remove qstr_mutex everywhere when MICROPY_PY_THREAD
&& !MICROPY_PY_THREAD_GIL.

py/qstr.c

diff --git a/py/qstr.c b/py/qstr.c
index 29ffcae..940d09e 100644
--- a/py/qstr.c
+++ b/py/qstr.c
@@ -125,7 +125,7 @@
     MP_STATE_VM(last_pool) = (qstr_pool_t*)&CONST_POOL; // we won't modify the const_pool since it has no allocated room left
     MP_STATE_VM(qstr_last_chunk) = NULL;
 
-    #if MICROPY_PY_THREAD
+    #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
     mp_thread_mutex_init(&MP_STATE_VM(qstr_mutex));
     #endif
 }