X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FSchedule.h;h=7760e364bd83aadf678018fab6567baf1b0e4765;hb=7dbc1d8f8fb650162e01f6eab8dabaf1f53c819d;hp=1e786ce690103c6f9b06b990869902fd98860dc7;hpb=2726a2f10256710cc6ed80b1098cb32e121e1be7;p=ghc-hetmet.git

diff --git a/rts/Schedule.h b/rts/Schedule.h
index 1e786ce..7760e36 100644
--- a/rts/Schedule.h
+++ b/rts/Schedule.h
@@ -155,7 +155,9 @@ popRunQueue (Capability *cap)
     StgTSO *t = cap->run_queue_hd;
     ASSERT(t != END_TSO_QUEUE);
     cap->run_queue_hd = t->_link;
-    cap->run_queue_hd->block_info.prev = END_TSO_QUEUE;
+    if (t->_link != END_TSO_QUEUE) {
+        t->_link->block_info.prev = END_TSO_QUEUE;
+    }
     t->_link = END_TSO_QUEUE; // no write barrier req'd
     if (cap->run_queue_hd == END_TSO_QUEUE) {
 	cap->run_queue_tl = END_TSO_QUEUE;