X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FSTM.c;h=b5dcc54884bac1368682ce1ca1a552d94adc3f49;hb=f5baf549bcd4b835fdc8e0ce00b854f522464e68;hp=c43e7ca4d81c36a11c6c6c32a4a15cdabbbb1a45;hpb=45202530612593a0ba7a6c559a38dc1ff26670a4;p=ghc-hetmet.git

diff --git a/rts/STM.c b/rts/STM.c
index c43e7ca..b5dcc54 100644
--- a/rts/STM.c
+++ b/rts/STM.c
@@ -389,9 +389,17 @@ static void unpark_tso(Capability *cap, StgTSO *tso) {
 static void unpark_waiters_on(Capability *cap, StgTVar *s) {
   StgTVarWatchQueue *q;
   TRACE("unpark_waiters_on tvar=%p", s);
-  for (q = s -> first_watch_queue_entry; 
-       q != END_STM_WATCH_QUEUE; 
+  StgTVarWatchQueue *trail;
+  // unblock TSOs in reverse order, to be a bit fairer (#2319)
+  for (q = s -> first_watch_queue_entry, trail = q;
+       q != END_STM_WATCH_QUEUE;
        q = q -> next_queue_entry) {
+    trail = q;
+  }
+  q = trail;
+  for (;
+       q != END_STM_WATCH_QUEUE; 
+       q = q -> prev_queue_entry) {
     if (watcher_is_tso(q)) {
       unpark_tso(cap, (StgTSO *)(q -> closure));
     }
@@ -1580,7 +1588,7 @@ static StgClosure *read_current_value(StgTRecHeader *trec STG_UNUSED, StgTVar *t
 StgClosure *stmReadTVar(Capability *cap,
                         StgTRecHeader *trec, 
 			StgTVar *tvar) {
-  StgTRecHeader *entry_in;
+  StgTRecHeader *entry_in = NULL;
   StgClosure *result = NULL;
   TRecEntry *entry = NULL;
   TRACE("%p : stmReadTVar(%p)", trec, tvar);
@@ -1623,7 +1631,7 @@ void stmWriteTVar(Capability *cap,
 		  StgTVar *tvar, 
 		  StgClosure *new_value) {
 
-  StgTRecHeader *entry_in;
+  StgTRecHeader *entry_in = NULL;
   TRecEntry *entry = NULL;
   TRACE("%p : stmWriteTVar(%p, %p)", trec, tvar, new_value);
   ASSERT (trec != NO_TREC);