[libc-commits] [libc] [libc] Fix atexit_test in hermetic mode (PR #210656)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Pavel Labath (labath)

<details>
<summary>Changes</summary>

We never unlocked the ThreadAtExit mutex, which meant the second call to exit deadlocked. This was detected in the unit tests as they were calling __cxa_thread_atexit from the system C library.

---
Full diff: https://github.com/llvm/llvm-project/pull/210656.diff


2 Files Affected:

- (modified) libc/src/__support/threads/thread.cpp (+1) 
- (modified) libc/test/src/stdlib/CMakeLists.txt (-2) 


``````````diff
diff --git a/libc/src/__support/threads/thread.cpp b/libc/src/__support/threads/thread.cpp
index ae179f068b88e..babcfdc5aea15 100644
--- a/libc/src/__support/threads/thread.cpp
+++ b/libc/src/__support/threads/thread.cpp
@@ -131,6 +131,7 @@ class ThreadAtExitCallbackMgr {
       atexit_unit.callback(atexit_unit.obj);
       mtx.lock();
     }
+    mtx.unlock();
   }
 };
 
diff --git a/libc/test/src/stdlib/CMakeLists.txt b/libc/test/src/stdlib/CMakeLists.txt
index 6a1b0069424d3..8e77d3fd08e11 100644
--- a/libc/test/src/stdlib/CMakeLists.txt
+++ b/libc/test/src/stdlib/CMakeLists.txt
@@ -531,8 +531,6 @@ if(LLVM_LIBC_FULL_BUILD)
 
   add_libc_test(
     atexit_test
-    # TODO: Fix this test in hermetic mode.
-    UNIT_TEST_ONLY
     SUITE
       libc-stdlib-tests
     SRCS

``````````

</details>


https://github.com/llvm/llvm-project/pull/210656