esp32/mpthreadport: Don't explicitly free thread struct in TCB cleanup.

dpgeorge · dpgeorge · commit 31e0b8c71c6e · 2021-05-08T22:47:03.000+10:00
Because vPortCleanUpTCB runs on the FreeRTOS idle task and cannot execute
any VM or runtime related code like freeing memory.

Signed-off-by: Damien George &lt;damien@micropython.org&gt;
diff --git a/ports/esp32/mpthreadport.c b/ports/esp32/mpthreadport.c
@@ -166,6 +166,8 @@ void mp_thread_finish(void) {
     mp_thread_mutex_unlock(&thread_mutex);
 }
 
+// This is called from the FreeRTOS idle task and is not within Python context,
+// so MP_STATE_THREAD is not valid and it does not have the GIL.
 void vPortCleanUpTCB(void *tcb) {
     if (thread == NULL) {
         // threading not yet initialised
@@ -182,8 +184,7 @@ void vPortCleanUpTCB(void *tcb) {
                 // move the start pointer
                 thread = th->next;
             }
-            // explicitly release all its memory
-            m_del(thread_t, th, 1);
+            // The "th" memory will eventually be reclaimed by the GC.
             break;
         }
     }

Original file line number	Diff line number	Diff line change
`@@ -166,6 +166,8 @@ void mp_thread_finish(void) {`
`166`	`166`	`mp_thread_mutex_unlock(&thread_mutex);`
`167`	`167`	`}`
`168`	`168`
	`169`	`+// This is called from the FreeRTOS idle task and is not within Python context,`
	`170`	`+// so MP_STATE_THREAD is not valid and it does not have the GIL.`
`169`	`171`	`void vPortCleanUpTCB(void *tcb) {`
`170`	`172`	`if (thread == NULL) {`
`171`	`173`	`// threading not yet initialised`
`@@ -182,8 +184,7 @@ void vPortCleanUpTCB(void *tcb) {`
`182`	`184`	`// move the start pointer`
`183`	`185`	`thread = th->next;`
`184`	`186`	`}`
`185`		`- // explicitly release all its memory`
`186`		`- m_del(thread_t, th, 1);`
	`187`	`+ // The "th" memory will eventually be reclaimed by the GC.`
`187`	`188`	`break;`
`188`	`189`	`}`
`189`	`190`	`}`