[OpenMP] Fix nested parallel with tasking

openmp/runtime/src/kmp_tasking.cpp

@@ -3219,7 +3219,7 @@ static kmp_task_t *__kmp_remove_my_task(kmp_info_t *thread, kmp_int32 gtid,
 // __kmp_steal_task: remove a task from another thread's deque
 // Assume that calling thread has already checked existence of
 // task_team thread_data before calling this routine.
-static kmp_task_t *__kmp_steal_task(kmp_info_t *victim_thr, kmp_int32 gtid,
+static kmp_task_t *__kmp_steal_task(kmp_int32 victim_tid, kmp_int32 gtid,
                                     kmp_task_team_t *task_team,
                                     std::atomic<kmp_int32> *unfinished_threads,
                                     int *thread_finished,
@@ -3229,15 +3229,18 @@ static kmp_task_t *__kmp_steal_task(kmp_info_t *victim_thr, kmp_int32 gtid,
   kmp_taskdata_t *current;
   kmp_thread_data_t *victim_td, *threads_data;
   kmp_int32 target;
-  kmp_int32 victim_tid;
+  kmp_info_t *victim_thr;
 
   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
 
   threads_data = task_team->tt.tt_threads_data;
   KMP_DEBUG_ASSERT(threads_data != NULL); // Caller should check this condition
+  KMP_DEBUG_ASSERT(victim_tid >= 0);
+  KMP_DEBUG_ASSERT(victim_tid < task_team->tt.tt_nproc);
 
-  victim_tid = victim_thr->th.th_info.ds.ds_tid;
   victim_td = &threads_data[victim_tid];
+  victim_thr = victim_td->td.td_thr;
+  (void)victim_thr; // Use in TRACE messages which aren't always enabled.
 
   KA_TRACE(10, ("__kmp_steal_task(enter): T#%d try to steal from T#%d: "
                 "task_team=%p ntasks=%d head=%u tail=%u\n",
@@ -3452,9 +3455,9 @@ static inline int __kmp_execute_tasks_template(
 
         if (!asleep) {
           // We have a victim to try to steal from
-          task = __kmp_steal_task(other_thread, gtid, task_team,
-                                  unfinished_threads, thread_finished,
-                                  is_constrained);
+          task =
+              __kmp_steal_task(victim_tid, gtid, task_team, unfinished_threads,
+                               thread_finished, is_constrained);
         }
         if (task != NULL) { // set last stolen to victim
           if (threads_data[tid].td.td_deque_last_stolen != victim_tid) {

openmp/runtime/test/tasking/issue-87307.c

@@ -0,0 +1,43 @@
+// RUN: %libomp-compile-and-run
+#include <stdio.h>
+#include <stdlib.h>
+#include <omp.h>
+
+int a;
+
+void inc_a() {
+#pragma omp task
+  {
+#pragma omp atomic
+    a++;
+  }
+}
+
+int main() {
+  int n;
+  int nth_outer;
+  omp_set_max_active_levels(2);
+  omp_set_dynamic(0);
+
+  for (n = 0; n < 200; ++n) {
+    a = 0;
+#pragma omp parallel num_threads(8)
+    {
+      if (omp_get_thread_num() == 0)
+        nth_outer = omp_get_num_threads();
+#pragma omp parallel num_threads(2)
+      {
+        int i;
+#pragma omp master
+        for (i = 0; i < 50; ++i)
+          inc_a();
+      }
+    }
+    if (a != nth_outer * 50) {
+      fprintf(stderr, "error: a (%d) != %d\n", a, nth_outer * 50);
+      return EXIT_FAILURE;
+    }
+  }
+
+  return EXIT_SUCCESS;
+}