do {
do {
result = s -> current_value;
- } while (GET_INFO(result) == &stg_TREC_HEADER_info);
+ } while (GET_INFO(UNTAG_CLOSURE(result)) == &stg_TREC_HEADER_info);
} while (cas((void *)&(s -> current_value),
(StgWord)result, (StgWord)trec) != (StgWord)result);
return result;
static void unpark_waiters_on(Capability *cap, StgTVar *s) {
StgTVarWatchQueue *q;
+ StgTVarWatchQueue *trail;
TRACE("unpark_waiters_on tvar=%p", s);
- for (q = s -> first_watch_queue_entry;
- q != END_STM_WATCH_QUEUE;
+ // 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));
}
result = tvar -> current_value;
#if defined(STM_FG_LOCKS)
- while (GET_INFO(result) == &stg_TREC_HEADER_info) {
+ while (GET_INFO(UNTAG_CLOSURE(result)) == &stg_TREC_HEADER_info) {
TRACE("%p : read_current_value(%p) saw %p", trec, tvar, result);
result = tvar -> current_value;
}