Use `Unlocked* ()` for operations on `joinable_thread_count`

- mark the (harmless) data race of the fastpath

diff --git a/mono/metadata/threads.c b/mono/metadata/threads.c
index 8eb4fe5f24e474e619a68bb2e17a00cb1f52f043..61e4531a3c79f92e19a26c38398ac039e111511e 100644 (file)
--- a/mono/metadata/threads.c
+++ b/mono/metadata/threads.c
@@ -45,6 +45,7 @@
 #include <mono/utils/mono-error-internals.h>
 #include <mono/utils/os-event.h>
 #include <mono/utils/mono-threads-debug.h>
+#include <mono/utils/unlocked.h>
 #include <mono/metadata/w32handle.h>
 #include <mono/metadata/w32event.h>
 #include <mono/metadata/w32mutex.h>
@@ -152,7 +153,7 @@ static MonoGHashTable *threads_starting_up = NULL;
 /* Contains tids */
 /* Protected by the threads lock */
 static GHashTable *joinable_threads;
-static int joinable_thread_count;
+static gint32 joinable_thread_count;
 
 #define SET_CURRENT_OBJECT(x) mono_tls_set_thread (x)
 #define GET_CURRENT_OBJECT() (MonoInternalThread*) mono_tls_get_thread ()
@@ -5000,7 +5001,7 @@ mono_threads_add_joinable_thread (gpointer tid)
        if (!joinable_threads)
                joinable_threads = g_hash_table_new (NULL, NULL);
        g_hash_table_insert (joinable_threads, tid, tid);
-       joinable_thread_count ++;
+       UnlockedIncrement (&joinable_thread_count);
        joinable_threads_unlock ();
 
        mono_gc_finalize_notify ();
@@ -5024,7 +5025,7 @@ mono_threads_join_threads (void)
        gboolean found;
 
        /* Fastpath */
-       if (!joinable_thread_count)
+       if (!UnlockedRead (&joinable_thread_count))
                return;
 
        while (TRUE) {
@@ -5035,7 +5036,7 @@ mono_threads_join_threads (void)
                        g_hash_table_iter_next (&iter, &key, (void**)&tid);
                        thread = (pthread_t)tid;
                        g_hash_table_remove (joinable_threads, key);
-                       joinable_thread_count --;
+                       UnlockedDecrement (&joinable_thread_count);
                        found = TRUE;
                }
                joinable_threads_unlock ();
@@ -5073,7 +5074,7 @@ mono_thread_join (gpointer tid)
                joinable_threads = g_hash_table_new (NULL, NULL);
        if (g_hash_table_lookup (joinable_threads, tid)) {
                g_hash_table_remove (joinable_threads, tid);
-               joinable_thread_count --;
+               UnlockedDecrement (&joinable_thread_count);
                found = TRUE;
        }
        joinable_threads_unlock ();

diff --git a/mono/utils/unlocked.h b/mono/utils/unlocked.h
index 19114ac61051812767258e9aee684f6fc99efe57..a989dafdbc7f0b7fdb143bbf4974658ba5608ffd 100644 (file)
--- a/mono/utils/unlocked.h
+++ b/mono/utils/unlocked.h
@@ -31,6 +31,13 @@ UnlockedIncrement (gint32 *val)
        return ++*val;
 }
 
+MONO_UNLOCKED_ATTRS
+gint32
+UnlockedDecrement (gint32 *val)
+{
+       return --*val;
+}
+
 MONO_UNLOCKED_ATTRS
 gint32
 UnlockedAdd (gint32 *dest, gint32 add)