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[OpenMP] Fix race condition in taskgraph with task dependencies #150880

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[OpenMP] Fix race condition in taskgraph with task dependencies #150880

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276c7d0
[OpenMP] Fix datarace with taskgraph dependencies and task stealing
jpinot Jul 7, 2025
6be40d0
Revert "[OpenMP] Fix datarace with taskgraph dependencies and task st…
jpinot Oct 7, 2025
f597923
[OpenMP] Fix successor reassignment race in taskgraph
jpinot Oct 7, 2025
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14 changes: 12 additions & 2 deletions openmp/runtime/src/kmp_taskdeps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -321,9 +321,19 @@ __kmp_depnode_link_successor(kmp_int32 gtid, kmp_info_t *thread,
__kmp_track_dependence(gtid, dep, node, task);
}
#endif
if (dep->dn.task) {
if (dep->dn.task
#if OMPX_TASKGRAPH
&& __kmp_tdg_is_recording(tdg_status) &&
!KMP_TASK_TO_TASKDATA(dep->dn.task)->td_flags.onced
#endif
) {
KMP_ACQUIRE_DEPNODE(gtid, dep);
if (dep->dn.task) {
if (dep->dn.task
#if OMPX_TASKGRAPH
&& __kmp_tdg_is_recording(tdg_status) &&
!KMP_TASK_TO_TASKDATA(dep->dn.task)->td_flags.onced
#endif
) {
if (!dep->dn.successors || dep->dn.successors->node != node) {
#if OMPX_TASKGRAPH
if (!(__kmp_tdg_is_recording(tdg_status)) && task)
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4 changes: 4 additions & 0 deletions openmp/runtime/src/kmp_taskdeps.h
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Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,10 @@ static inline void __kmp_release_deps(kmp_int32 gtid, kmp_taskdata_t *task) {
#endif
node->dn.task =
NULL; // mark this task as finished, so no new dependencies are generated
#if OMPX_TASKGRAPH
else
KMP_TASK_TO_TASKDATA(node->dn.task)->td_flags.onced = 1;
#endif
KMP_RELEASE_DEPNODE(gtid, node);

kmp_depnode_list_t *next;
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