From 42c917df5be8d75f79a283a8ed59fbaf099bc973 Mon Sep 17 00:00:00 2001
From: Adam Sandberg Ericsson <adam@sandbergericsson.se>
Date: Sat, 18 Jun 2022 10:01:22 +0100
Subject: rts: allow NULL to be used as an invalid StgStablePtr

---
 rts/TopHandler.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'rts/TopHandler.c')

diff --git a/rts/TopHandler.c b/rts/TopHandler.c
index d5175015e7..f3ab55c85e 100644
--- a/rts/TopHandler.c
+++ b/rts/TopHandler.c
@@ -28,6 +28,10 @@ StgTSO *getTopHandlerThread(void) {
     ACQUIRE_LOCK(&m);
     StgWeak *weak = (StgWeak*)deRefStablePtr(topHandlerPtr);
     RELEASE_LOCK(&m);
+    if (weak == NULL) {
+        // topHandlerPtr was never initialised
+        return NULL;
+    }
     const StgInfoTable *info = weak->header.info;
     load_load_barrier();
     if (info == &stg_WEAK_info) {
-- 
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