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gh-111924: Fix data races when swapping allocators (gh-130287)
CPython current temporarily changes `PYMEM_DOMAIN_RAW` to the default allocator during initialization and shutdown. The motivation is to ensure that core runtime structures are allocated and freed using the same allocator. However, modifying the current allocator changes global state and is not thread-safe even with the GIL. Other threads may be allocating or freeing objects use PYMEM_DOMAIN_RAW; they are not required to hold the GIL to call PyMem_RawMalloc/PyMem_RawFree. This adds new internal-only functions like `_PyMem_DefaultRawMalloc` that aren't affected by calls to `PyMem_SetAllocator()`, so they're appropriate for Python runtime initialization and finalization. Use these calls in places where we previously swapped to the default raw allocator.
This commit is contained in:
Sam Gross
GitHub
parent
568db400ff
commit
ca22147547
9 changed files with 155 additions and 154 deletions
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@ -4,7 +4,7 @@
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#include "pycore_initconfig.h" // _PyStatus_OK()
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#include "pycore_fileutils.h" // _Py_wgetcwd()
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#include "pycore_pathconfig.h"
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#include "pycore_pymem.h" // _PyMem_SetDefaultAllocator()
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#include "pycore_pymem.h" // _PyMem_DefaultRawFree()
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#include <wchar.h>
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#include "marshal.h" // PyMarshal_ReadObjectFromString
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@ -54,12 +54,9 @@ _PyPathConfig_GetGlobalModuleSearchPath(void)
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void
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_PyPathConfig_ClearGlobal(void)
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{
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PyMemAllocatorEx old_alloc;
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_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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#define CLEAR(ATTR) \
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do { \
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PyMem_RawFree(_Py_path_config.ATTR); \
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_PyMem_DefaultRawFree(_Py_path_config.ATTR); \
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_Py_path_config.ATTR = NULL; \
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} while (0)
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@ -74,8 +71,6 @@ _PyPathConfig_ClearGlobal(void)
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_Py_path_config._is_python_build = 0;
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#undef CLEAR
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PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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}
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PyStatus
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@ -126,14 +121,11 @@ done:
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PyStatus
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_PyPathConfig_UpdateGlobal(const PyConfig *config)
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{
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PyMemAllocatorEx old_alloc;
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_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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#define COPY(ATTR) \
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do { \
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if (config->ATTR) { \
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PyMem_RawFree(_Py_path_config.ATTR); \
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_Py_path_config.ATTR = _PyMem_RawWcsdup(config->ATTR); \
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_PyMem_DefaultRawFree(_Py_path_config.ATTR); \
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_Py_path_config.ATTR = _PyMem_DefaultRawWcsdup(config->ATTR); \
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if (!_Py_path_config.ATTR) goto error; \
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} \
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} while (0)
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@ -141,8 +133,8 @@ _PyPathConfig_UpdateGlobal(const PyConfig *config)
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#define COPY2(ATTR, SRCATTR) \
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do { \
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if (config->SRCATTR) { \
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PyMem_RawFree(_Py_path_config.ATTR); \
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_Py_path_config.ATTR = _PyMem_RawWcsdup(config->SRCATTR); \
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_PyMem_DefaultRawFree(_Py_path_config.ATTR); \
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_Py_path_config.ATTR = _PyMem_DefaultRawWcsdup(config->SRCATTR); \
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if (!_Py_path_config.ATTR) goto error; \
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} \
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} while (0)
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@ -165,9 +157,9 @@ _PyPathConfig_UpdateGlobal(const PyConfig *config)
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#undef COPY2
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#undef COPY_INT
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PyMem_RawFree(_Py_path_config.module_search_path);
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_PyMem_DefaultRawFree(_Py_path_config.module_search_path);
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_Py_path_config.module_search_path = NULL;
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PyMem_RawFree(_Py_path_config.calculated_module_search_path);
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_PyMem_DefaultRawFree(_Py_path_config.calculated_module_search_path);
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_Py_path_config.calculated_module_search_path = NULL;
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do {
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@ -176,7 +168,7 @@ _PyPathConfig_UpdateGlobal(const PyConfig *config)
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cch += 1 + wcslen(config->module_search_paths.items[i]);
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}
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wchar_t *path = (wchar_t*)PyMem_RawMalloc(sizeof(wchar_t) * cch);
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wchar_t *path = (wchar_t*)_PyMem_DefaultRawMalloc(sizeof(wchar_t) * cch);
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if (!path) {
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goto error;
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}
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@ -194,11 +186,9 @@ _PyPathConfig_UpdateGlobal(const PyConfig *config)
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_Py_path_config.calculated_module_search_path = path;
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} while (0);
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PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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return _PyStatus_OK();
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error:
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PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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return _PyStatus_NO_MEMORY();
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}
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@ -218,29 +208,24 @@ Py_SetPath(const wchar_t *path)
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return;
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}
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PyMemAllocatorEx old_alloc;
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_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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_PyMem_DefaultRawFree(_Py_path_config.prefix);
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_PyMem_DefaultRawFree(_Py_path_config.exec_prefix);
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_PyMem_DefaultRawFree(_Py_path_config.stdlib_dir);
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_PyMem_DefaultRawFree(_Py_path_config.module_search_path);
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_PyMem_DefaultRawFree(_Py_path_config.calculated_module_search_path);
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PyMem_RawFree(_Py_path_config.prefix);
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PyMem_RawFree(_Py_path_config.exec_prefix);
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PyMem_RawFree(_Py_path_config.stdlib_dir);
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PyMem_RawFree(_Py_path_config.module_search_path);
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PyMem_RawFree(_Py_path_config.calculated_module_search_path);
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_Py_path_config.prefix = _PyMem_RawWcsdup(L"");
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_Py_path_config.exec_prefix = _PyMem_RawWcsdup(L"");
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_Py_path_config.prefix = _PyMem_DefaultRawWcsdup(L"");
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_Py_path_config.exec_prefix = _PyMem_DefaultRawWcsdup(L"");
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// XXX Copy this from the new module_search_path?
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if (_Py_path_config.home != NULL) {
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_Py_path_config.stdlib_dir = _PyMem_RawWcsdup(_Py_path_config.home);
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_Py_path_config.stdlib_dir = _PyMem_DefaultRawWcsdup(_Py_path_config.home);
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}
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else {
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_Py_path_config.stdlib_dir = _PyMem_RawWcsdup(L"");
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_Py_path_config.stdlib_dir = _PyMem_DefaultRawWcsdup(L"");
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}
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_Py_path_config.module_search_path = _PyMem_RawWcsdup(path);
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_Py_path_config.module_search_path = _PyMem_DefaultRawWcsdup(path);
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_Py_path_config.calculated_module_search_path = NULL;
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PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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if (_Py_path_config.prefix == NULL
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|| _Py_path_config.exec_prefix == NULL
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|| _Py_path_config.stdlib_dir == NULL
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@ -256,18 +241,13 @@ Py_SetPythonHome(const wchar_t *home)
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{
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int has_value = home && home[0];
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PyMemAllocatorEx old_alloc;
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_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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PyMem_RawFree(_Py_path_config.home);
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_PyMem_DefaultRawFree(_Py_path_config.home);
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_Py_path_config.home = NULL;
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if (has_value) {
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_Py_path_config.home = _PyMem_RawWcsdup(home);
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_Py_path_config.home = _PyMem_DefaultRawWcsdup(home);
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}
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PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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if (has_value && _Py_path_config.home == NULL) {
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path_out_of_memory(__func__);
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}
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@ -279,18 +259,13 @@ Py_SetProgramName(const wchar_t *program_name)
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{
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int has_value = program_name && program_name[0];
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PyMemAllocatorEx old_alloc;
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_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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PyMem_RawFree(_Py_path_config.program_name);
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_PyMem_DefaultRawFree(_Py_path_config.program_name);
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_Py_path_config.program_name = NULL;
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if (has_value) {
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_Py_path_config.program_name = _PyMem_RawWcsdup(program_name);
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_Py_path_config.program_name = _PyMem_DefaultRawWcsdup(program_name);
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}
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PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
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if (has_value && _Py_path_config.program_name == NULL) {
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path_out_of_memory(__func__);
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}
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