[Lldb-commits] [lldb] [LLDB] Fix potential data race in Symtab initialization (PR #192753)

[Adrian Prantl via lldb-commits]

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@@ -1126,6 +1126,7 @@ void Symtab::FindFunctionSymbols(ConstString name, uint32_t name_type_mask,
     }
   }
 
+  std::lock_guard<std::recursive_mutex> guard(m_mutex);
   if (!m_name_indexes_computed)
     InitNameIndexes();
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adrian-prantl wrote:

I don't think that's a safe change because the block below calls `GetNameToSymbolIndexMap(type)` which accesses yet another member without any guards.

The entire interface of this class is relying on callers acquiring the mutex. I don't really know how expensive locking an already acquired recursive_mutex is, but assuming it is prohibitively expensive, a better interface would be a wrapper object that returns a locked query object and makes it impossible to forget to hold the mutex.

I did remove the redundant checks around the invocations of InitNameIndexes() though.

https://github.com/llvm/llvm-project/pull/192753