[Openmp-commits] [PATCH] D159324: [OpenMP] Fix a segment fault in __kmp_get_global_thread_id

[Shilei Tian via Phabricator via Openmp-commits]

tianshilei1992 created this revision.
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In `__kmp_get_global_thread_id`, if the gtid mode is 1, after getting the gtid
from TLS, it will store the gtid value to the thread stack maintained in the thread
descriptor. However, `__kmp_get_global_thread_id` can be called when the library
is destructed, after the corresponding thread info has been release. This will
cause a segment fault. This can happen on an Intel-based Mac.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D159324

Files:
  openmp/runtime/src/kmp_runtime.cpp


Index: openmp/runtime/src/kmp_runtime.cpp
===================================================================
--- openmp/runtime/src/kmp_runtime.cpp
+++ openmp/runtime/src/kmp_runtime.cpp
@@ -196,6 +196,11 @@
   if (i < 0)
     return i;
 
+  // other_threads[i] can be nullptr at this point because the corresponding
+  // thread could have already been release.
+  if (!TCR_SYNC_PTR(other_threads[i]))
+    return i;
+
   /* dynamically updated stack window for uber threads to avoid get_specific
      call */
   if (!TCR_4(other_threads[i]->th.th_info.ds.ds_stackgrow)) {


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