[coop] Reuse local info variable for polling

This would lead to a crash when unregistering the thread from the currnt MonoThreadInfo* destructor, as `mono_thread_info_current_unchecked` would return NULL. This would trigger an infinite loop in `mono_threads_enter_gc_safe_region_unbalanced_with_info`.

diff --git a/mono/utils/mono-threads-coop.c b/mono/utils/mono-threads-coop.c
index 4803ad9656f741fb52940b5c32823942e54f2232..ddc3c6ebbe231b49371e86760e198272c3d08191 100644 (file)
--- a/mono/utils/mono-threads-coop.c
+++ b/mono/utils/mono-threads-coop.c
@@ -103,18 +103,25 @@ static int coop_do_blocking_count;
 static int coop_do_polling_count;
 static int coop_save_count;
 
+static void
+mono_threads_state_poll_with_info (MonoThreadInfo *info);
+
 void
 mono_threads_state_poll (void)
 {
-       MonoThreadInfo *info;
+       mono_threads_state_poll_with_info (mono_thread_info_current_unchecked ());
+}
 
+static void
+mono_threads_state_poll_with_info (MonoThreadInfo *info)
+{
        g_assert (mono_threads_is_coop_enabled ());
 
        ++coop_do_polling_count;
 
-       info = mono_thread_info_current_unchecked ();
        if (!info)
                return;
+
        THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", mono_thread_info_get_tid (info));
 
        /* Fast check for pending suspend requests */
@@ -226,7 +233,7 @@ retry:
        case DoBlockingContinue:
                break;
        case DoBlockingPollAndRetry:
-               mono_threads_state_poll ();
+               mono_threads_state_poll_with_info (info);
                goto retry;
        }
 
@@ -325,7 +332,7 @@ mono_threads_enter_gc_unsafe_region_unbalanced_with_info (MonoThreadInfo *info,
                info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
                return NULL;
        case AbortBlockingIgnoreAndPoll:
-               mono_threads_state_poll ();
+               mono_threads_state_poll_with_info (info);
                return NULL;
        case AbortBlockingOk:
                info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;