Disallow explicit unregister of non-main thread if registered by DllMain

This is to match the behavior on non-Windows platforms (and to match
the comment of GC_delete_thread).

* include/private/pthread_support.h [GC_WIN32_THREADS
&& !GC_NO_THREADS_DISCOVERY && GC_ASSERTIONS] (GC_main_thread_id):
Declare variable.
* include/private/pthread_support.h [GC_WIN32_THREADS
&& !GC_NO_THREADS_DISCOVERY] (GC_delete_thread): Remove.
* pthread_support.c (GC_delete_thread): Change GC_INNER_WIN32THREAD to
STATIC.
* pthread_support.c [!GC_NO_THREADS_DISCOVERY && GC_WIN32_THREADS]
(GC_delete_thread): Call GC_win32_dll_lookup_thread instead of
GC_lookup_thread and do not check its result.
* pthread_support.c [!GC_NO_THREADS_DISCOVERY && GC_WIN32_THREADS]
(GC_unregister_my_thread): Do not call GC_delete_thread (directly) if
GC_win32_dll_threads; add assertion to check that the thread to b
unregistered is main one if GC_win32_dll_threads; add comment.
* win32_threads.c [!GC_NO_THREADS_DISCOVERY] (main_thread_id): Rename
to GC_main_thread_id and change static to GC_INNER to STATIC.
* win32_threads.c (GC_register_my_thread_inner): Update comment to
mention GC_win32_dll_lookup_thread instead of GC_delete_thread.
* win32_threads.c (GC_thr_init): Define self_id local variable and use
it instead of main_thread_id; do not define main_thread_id as macro;
do not undefine main_thread_id.
* win32_threads.c [!GC_NO_THREADS_DISCOVERY] (GC_DllMain): Call
GC_win32_dll_lookup_thread() and GC_delete_gc_thread_no_free() instead
of GC_delete_thread() (w/o a warning if the thread is not found).

1 files changed, 10 insertions, 21 deletions

diff --git a/pthread_support.c b/pthread_support.c
index 08d52375..808ec458 100644
--- a/pthread_support.c
+++ b/pthread_support.c
@@ -743,17 +743,13 @@ GC_INNER_WIN32THREAD GC_thread GC_new_thread(thread_id_t id)
 /* If GC_win32_dll_threads is set then it should be called from */
 /* the thread being deleted.  It is also safe to delete the     */
 /* main thread (unless GC_win32_dll_threads).                   */
-GC_INNER_WIN32THREAD void GC_delete_thread(thread_id_t id)
+STATIC void GC_delete_thread(thread_id_t id)
 {
 # if !defined(GC_NO_THREADS_DISCOVERY) && defined(GC_WIN32_THREADS)
     if (GC_win32_dll_threads) {
-      GC_thread t = GC_lookup_thread(id);
+      GC_thread t = GC_win32_dll_lookup_thread(id);
 
-      if (EXPECT(NULL == t, FALSE)) {
-        WARN("Removing nonexistent thread, id= %" WARN_PRIuPTR "\n", id);
-      } else {
-        GC_delete_gc_thread_no_free(t);
-      }
+      GC_delete_gc_thread_no_free(t);
     } else
 # endif
   /* else */ {
@@ -2146,23 +2142,17 @@ STATIC void GC_unregister_my_thread_inner(GC_thread me)
 
 GC_API int GC_CALL GC_unregister_my_thread(void)
 {
-# if !defined(GC_NO_THREADS_DISCOVERY) && defined(GC_WIN32_THREADS)
-    if (GC_win32_dll_threads) {
-#     ifdef THREAD_LOCAL_ALLOC
-        /* Can't happen: see GC_use_threads_discovery().        */
-        GC_ASSERT(FALSE);
-#     else
-        /* FIXME: Should we just ignore this? */
-        GC_delete_thread(thread_id_self());
-#     endif
-    } else
-# endif
-  /* else */ {
     thread_id_t self_id = thread_id_self();
     GC_thread me;
     IF_CANCEL(int cancel_state;)
     DCL_LOCK_STATE;
 
+    /* Client should not unregister the thread explicitly if it */
+    /* is registered by DllMain, except for the main thread.    */
+#   if !defined(GC_NO_THREADS_DISCOVERY) && defined(GC_WIN32_THREADS)
+      GC_ASSERT(!GC_win32_dll_threads || GC_main_thread_id == self_id);
+#   endif
+
     LOCK();
     DISABLE_CANCEL(cancel_state);
     /* Wait for any GC that may be marking from our stack to    */
@@ -2178,8 +2168,7 @@ GC_API int GC_CALL GC_unregister_my_thread(void)
     GC_unregister_my_thread_inner(me);
     RESTORE_CANCEL(cancel_state);
     UNLOCK();
-  }
-  return GC_SUCCESS;
+    return GC_SUCCESS;
 }
 
 #if !defined(GC_NO_PTHREAD_CANCEL) && defined(GC_PTHREADS)