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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Data race in std::unique_lock"
href="https://bugs.llvm.org/show_bug.cgi?id=50365">50365</a>
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<th>Summary</th>
<td>Data race in std::unique_lock
</td>
</tr>
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<th>Product</th>
<td>libc++
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>All Bugs
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>sololev27@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>There are two lines in ```unique_lock::unlock``` that should appear in reverse
order:
<a href="https://github.com/llvm/llvm-project/blob/d480f968ad8b56d3ee4a6b6df5532d485b0ad01e/libcxx/include/__mutex_base#L255">https://github.com/llvm/llvm-project/blob/d480f968ad8b56d3ee4a6b6df5532d485b0ad01e/libcxx/include/__mutex_base#L255</a>
<a href="https://github.com/llvm/llvm-project/blob/d480f968ad8b56d3ee4a6b6df5532d485b0ad01e/libcxx/include/__mutex_base#L256">https://github.com/llvm/llvm-project/blob/d480f968ad8b56d3ee4a6b6df5532d485b0ad01e/libcxx/include/__mutex_base#L256</a>
MRE would require a thread pool with fibers running over it (that's how TSan
detected the race condition in the first place) so that one thread has unlocked
```__m_``` but not written false yet, and another thread is destroying the lock
already.</pre>
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</p>
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