From 13264ca8fc70dccda2bfa617fac3033042624e25 Mon Sep 17 00:00:00 2001
From: Matt Page <mpage@meta.com>
Date: Thu, 25 Apr 2024 16:06:46 -0700
Subject: [PATCH 1/2] Disable the function/code cache in free-threaded builds

This is only used by the specializing interpreter and the tier 2
optimizer, both of which are disabled in free-threaded builds.

[Sample race](https://gist.github.com/mpage/d05a1c4616eedc9337f3f335e6485f91) that is fixed.
---
 Include/internal/pycore_function.h         |  7 +++++++
 Objects/codeobject.c                       |  6 ++++++
 Objects/funcobject.c                       | 10 ++++++++++
 Tools/tsan/suppressions_free_threading.txt |  1 -
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/Include/internal/pycore_function.h b/Include/internal/pycore_function.h
index 24fbb3ddbee602..5b21eb96a3c45f 100644
--- a/Include/internal/pycore_function.h
+++ b/Include/internal/pycore_function.h
@@ -4,6 +4,8 @@
 extern "C" {
 #endif
 
+#include "pycore_lock.h"
+
 #ifndef Py_BUILD_CORE
 #  error "this header requires Py_BUILD_CORE define"
 #endif
@@ -24,6 +26,11 @@ struct _func_version_cache_item {
 };
 
 struct _py_func_state {
+    #ifdef Py_GIL_DISABLED
+    // Protects next_version
+    PyMutex mutex;
+    #endif
+
     uint32_t next_version;
     // Borrowed references to function and code objects whose
     // func_version % FUNC_VERSION_CACHE_SIZE
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index 014632962bfcf3..14a12590361902 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -416,10 +416,16 @@ init_code(PyCodeObject *co, struct _PyCodeConstructor *con)
     co->co_ncellvars = ncellvars;
     co->co_nfreevars = nfreevars;
     PyInterpreterState *interp = _PyInterpreterState_GET();
+#ifdef Py_GIL_DISABLED
+    PyMutex_Lock(&interp->func_state.mutex);
+#endif
     co->co_version = interp->func_state.next_version;
     if (interp->func_state.next_version != 0) {
         interp->func_state.next_version++;
     }
+#ifdef Py_GIL_DISABLED
+    PyMutex_Unlock(&interp->func_state.mutex);
+#endif
     co->_co_monitoring = NULL;
     co->_co_instrumentation_version = 0;
     /* not set */
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index 276b3db2970371..8a30213888ef87 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -287,6 +287,7 @@ functions is running.
 void
 _PyFunction_SetVersion(PyFunctionObject *func, uint32_t version)
 {
+#ifndef Py_GIL_DISABLED
     PyInterpreterState *interp = _PyInterpreterState_GET();
     if (func->func_version != 0) {
         struct _func_version_cache_item *slot =
@@ -297,7 +298,9 @@ _PyFunction_SetVersion(PyFunctionObject *func, uint32_t version)
             // Leave slot->code alone, there may be use for it.
         }
     }
+#endif
     func->func_version = version;
+#ifndef Py_GIL_DISABLED
     if (version != 0) {
         struct _func_version_cache_item *slot =
             interp->func_state.func_version_cache
@@ -305,11 +308,13 @@ _PyFunction_SetVersion(PyFunctionObject *func, uint32_t version)
         slot->func = func;
         slot->code = func->func_code;
     }
+#endif
 }
 
 void
 _PyFunction_ClearCodeByVersion(uint32_t version)
 {
+#ifndef Py_GIL_DISABLED
     PyInterpreterState *interp = _PyInterpreterState_GET();
     struct _func_version_cache_item *slot =
         interp->func_state.func_version_cache
@@ -322,11 +327,15 @@ _PyFunction_ClearCodeByVersion(uint32_t version)
             slot->func = NULL;
         }
     }
+#endif
 }
 
 PyFunctionObject *
 _PyFunction_LookupByVersion(uint32_t version, PyObject **p_code)
 {
+#ifdef Py_GIL_DISABLED
+    return NULL;
+#else
     PyInterpreterState *interp = _PyInterpreterState_GET();
     struct _func_version_cache_item *slot =
         interp->func_state.func_version_cache
@@ -346,6 +355,7 @@ _PyFunction_LookupByVersion(uint32_t version, PyObject **p_code)
         return slot->func;
     }
     return NULL;
+#endif
 }
 
 uint32_t
diff --git a/Tools/tsan/suppressions_free_threading.txt b/Tools/tsan/suppressions_free_threading.txt
index e4ca32bebc5a22..06874d4982215c 100644
--- a/Tools/tsan/suppressions_free_threading.txt
+++ b/Tools/tsan/suppressions_free_threading.txt
@@ -16,7 +16,6 @@ race:_in_weak_set
 race:_mi_heap_delayed_free_partial
 race:_Py_IsOwnedByCurrentThread
 race:_PyEval_EvalFrameDefault
-race:_PyFunction_SetVersion
 race:_PyImport_AcquireLock
 race:_PyImport_ReleaseLock
 race:_PyInterpreterState_SetNotRunningMain

From 912fed24d8c3d2c81466ea27cd41ae6ce0e7ac83 Mon Sep 17 00:00:00 2001
From: Matt Page <mpage@meta.com>
Date: Thu, 25 Apr 2024 18:24:24 -0700
Subject: [PATCH 2/2] Fix indentation

---
 Include/internal/pycore_function.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Include/internal/pycore_function.h b/Include/internal/pycore_function.h
index 5b21eb96a3c45f..6d44e933e8a8cb 100644
--- a/Include/internal/pycore_function.h
+++ b/Include/internal/pycore_function.h
@@ -26,10 +26,10 @@ struct _func_version_cache_item {
 };
 
 struct _py_func_state {
-    #ifdef Py_GIL_DISABLED
+#ifdef Py_GIL_DISABLED
     // Protects next_version
     PyMutex mutex;
-    #endif
+#endif
 
     uint32_t next_version;
     // Borrowed references to function and code objects whose