[Lldb-commits] [lldb] a659857 - [LLDB] Fix Python GIL-not-held issues
Pavel Labath via lldb-commits
lldb-commits at lists.llvm.org
Mon Jan 17 01:32:25 PST 2022
Author: Ralf Grosse-Kunstleve
Date: 2022-01-17T10:32:19+01:00
New Revision: a6598575f4bc20f9a01c2bced2d0b1ff14d7576f
URL: https://github.com/llvm/llvm-project/commit/a6598575f4bc20f9a01c2bced2d0b1ff14d7576f
DIFF: https://github.com/llvm/llvm-project/commit/a6598575f4bc20f9a01c2bced2d0b1ff14d7576f.diff
LOG: [LLDB] Fix Python GIL-not-held issues
The GIL must be held when calling any Python C API functions. In multithreaded applications that use callbacks this requirement can easily be violated by accident. A general tool to ensure GIL health is not available, but patching Python Py_INCREF to add an assert provides a basic health check:
```
+int PyGILState_Check(void); /* Include/internal/pystate.h */
+
#define Py_INCREF(op) ( \
+ assert(PyGILState_Check()), \
_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
((PyObject *)(op))->ob_refcnt++)
#define Py_DECREF(op) \
do { \
+ assert(PyGILState_Check()); \
PyObject *_py_decref_tmp = (PyObject *)(op); \
if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \
--(_py_decref_tmp)->ob_refcnt != 0) \
```
Adding this assertion causes around 50 test failures in LLDB. Adjusting the scope of things guarded by `py_lock` fixes them.
More background: https://docs.python.org/3/glossary.html#term-global-interpreter-lock
Patch by Ralf Grosse-Kunstleve
Differential Revision: https://reviews.llvm.org/D114722
Added:
Modified:
lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
Removed:
################################################################################
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
index 7c71c9329e579..d68af672ae83e 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
@@ -257,6 +257,7 @@ PythonObject PythonObject::GetAttributeValue(llvm::StringRef attr) const {
}
StructuredData::ObjectSP PythonObject::CreateStructuredObject() const {
+ assert(PyGILState_Check());
switch (GetObjectType()) {
case PyObjectType::Dictionary:
return PythonDictionary(PyRefType::Borrowed, m_py_obj)
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
index 56bc55d239d12..9d2cdca45a633 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
@@ -88,12 +88,21 @@ class StructuredPythonObject : public StructuredData::Generic {
StructuredPythonObject() : StructuredData::Generic() {}
StructuredPythonObject(void *obj) : StructuredData::Generic(obj) {
+ assert(PyGILState_Check());
Py_XINCREF(GetValue());
}
~StructuredPythonObject() override {
- if (Py_IsInitialized())
- Py_XDECREF(GetValue());
+ if (Py_IsInitialized()) {
+ if (_Py_IsFinalizing()) {
+ // Leak GetValue() rather than crashing the process.
+ // https://docs.python.org/3/c-api/init.html#c.PyGILState_Ensure
+ } else {
+ PyGILState_STATE state = PyGILState_Ensure();
+ Py_XDECREF(GetValue());
+ PyGILState_Release(state);
+ }
+ }
SetValue(nullptr);
}
@@ -264,8 +273,16 @@ class PythonObject {
~PythonObject() { Reset(); }
void Reset() {
- if (m_py_obj && Py_IsInitialized())
- Py_DECREF(m_py_obj);
+ if (m_py_obj && Py_IsInitialized()) {
+ if (_Py_IsFinalizing()) {
+ // Leak m_py_obj rather than crashing the process.
+ // https://docs.python.org/3/c-api/init.html#c.PyGILState_Ensure
+ } else {
+ PyGILState_STATE state = PyGILState_Ensure();
+ Py_DECREF(m_py_obj);
+ PyGILState_Release(state);
+ }
+ }
m_py_obj = nullptr;
}
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
index ed4ad279f5281..96725afd279ed 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -1438,14 +1438,9 @@ ScriptInterpreterPythonImpl::CreateFrameRecognizer(const char *class_name) {
if (class_name == nullptr || class_name[0] == '\0')
return StructuredData::GenericSP();
- void *ret_val;
-
- {
- Locker py_lock(this, Locker::AcquireLock | Locker::NoSTDIN,
- Locker::FreeLock);
- ret_val = LLDBSWIGPython_CreateFrameRecognizer(class_name,
- m_dictionary_name.c_str());
- }
+ Locker py_lock(this, Locker::AcquireLock | Locker::NoSTDIN, Locker::FreeLock);
+ void *ret_val = LLDBSWIGPython_CreateFrameRecognizer(
+ class_name, m_dictionary_name.c_str());
return StructuredData::GenericSP(new StructuredPythonObject(ret_val));
}
@@ -1502,14 +1497,9 @@ ScriptInterpreterPythonImpl::OSPlugin_CreatePluginObject(
if (!process_sp)
return StructuredData::GenericSP();
- void *ret_val;
-
- {
- Locker py_lock(this, Locker::AcquireLock | Locker::NoSTDIN,
- Locker::FreeLock);
- ret_val = LLDBSWIGPythonCreateOSPlugin(
- class_name, m_dictionary_name.c_str(), process_sp);
- }
+ Locker py_lock(this, Locker::AcquireLock | Locker::NoSTDIN, Locker::FreeLock);
+ void *ret_val = LLDBSWIGPythonCreateOSPlugin(
+ class_name, m_dictionary_name.c_str(), process_sp);
return StructuredData::GenericSP(new StructuredPythonObject(ret_val));
}
@@ -1757,17 +1747,13 @@ StructuredData::ObjectSP ScriptInterpreterPythonImpl::CreateScriptedThreadPlan(
if (!python_interpreter)
return {};
- void *ret_val;
-
- {
- Locker py_lock(this,
- Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
- ret_val = LLDBSwigPythonCreateScriptedThreadPlan(
- class_name, python_interpreter->m_dictionary_name.c_str(),
- args_data, error_str, thread_plan_sp);
- if (!ret_val)
- return {};
- }
+ Locker py_lock(this,
+ Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
+ void *ret_val = LLDBSwigPythonCreateScriptedThreadPlan(
+ class_name, python_interpreter->m_dictionary_name.c_str(), args_data,
+ error_str, thread_plan_sp);
+ if (!ret_val)
+ return {};
return StructuredData::ObjectSP(new StructuredPythonObject(ret_val));
}
@@ -1860,16 +1846,12 @@ ScriptInterpreterPythonImpl::CreateScriptedBreakpointResolver(
if (!python_interpreter)
return StructuredData::GenericSP();
- void *ret_val;
-
- {
- Locker py_lock(this,
- Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
+ Locker py_lock(this,
+ Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
- ret_val = LLDBSwigPythonCreateScriptedBreakpointResolver(
- class_name, python_interpreter->m_dictionary_name.c_str(), args_data,
- bkpt_sp);
- }
+ void *ret_val = LLDBSwigPythonCreateScriptedBreakpointResolver(
+ class_name, python_interpreter->m_dictionary_name.c_str(), args_data,
+ bkpt_sp);
return StructuredData::GenericSP(new StructuredPythonObject(ret_val));
}
@@ -1935,16 +1917,12 @@ StructuredData::GenericSP ScriptInterpreterPythonImpl::CreateScriptedStopHook(
return StructuredData::GenericSP();
}
- void *ret_val;
-
- {
- Locker py_lock(this,
- Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
+ Locker py_lock(this,
+ Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
- ret_val = LLDBSwigPythonCreateScriptedStopHook(
- target_sp, class_name, python_interpreter->m_dictionary_name.c_str(),
- args_data, error);
- }
+ void *ret_val = LLDBSwigPythonCreateScriptedStopHook(
+ target_sp, class_name, python_interpreter->m_dictionary_name.c_str(),
+ args_data, error);
return StructuredData::GenericSP(new StructuredPythonObject(ret_val));
}
@@ -2035,14 +2013,10 @@ ScriptInterpreterPythonImpl::CreateSyntheticScriptedProvider(
if (!python_interpreter)
return StructuredData::ObjectSP();
- void *ret_val = nullptr;
-
- {
- Locker py_lock(this,
- Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
- ret_val = LLDBSwigPythonCreateSyntheticProvider(
- class_name, python_interpreter->m_dictionary_name.c_str(), valobj);
- }
+ Locker py_lock(this,
+ Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
+ void *ret_val = LLDBSwigPythonCreateSyntheticProvider(
+ class_name, python_interpreter->m_dictionary_name.c_str(), valobj);
return StructuredData::ObjectSP(new StructuredPythonObject(ret_val));
}
@@ -2057,14 +2031,10 @@ ScriptInterpreterPythonImpl::CreateScriptCommandObject(const char *class_name) {
if (!debugger_sp.get())
return StructuredData::GenericSP();
- void *ret_val;
-
- {
- Locker py_lock(this,
- Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
- ret_val = LLDBSwigPythonCreateCommandObject(
- class_name, m_dictionary_name.c_str(), debugger_sp);
- }
+ Locker py_lock(this,
+ Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
+ void *ret_val = LLDBSwigPythonCreateCommandObject(
+ class_name, m_dictionary_name.c_str(), debugger_sp);
return StructuredData::GenericSP(new StructuredPythonObject(ret_val));
}
@@ -2176,8 +2146,11 @@ bool ScriptInterpreterPythonImpl::GetScriptedSummary(
return false;
}
- if (new_callee && old_callee != new_callee)
+ if (new_callee && old_callee != new_callee) {
+ Locker py_lock(this,
+ Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
callee_wrapper_sp = std::make_shared<StructuredPythonObject>(new_callee);
+ }
return ret_val;
}
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