https://github.com/python/cpython/commit/d027787c8d89f59a9f0b1d7cc6972f5e16ffc740
commit: d027787c8d89f59a9f0b1d7cc6972f5e16ffc740
branch: main
author: Sam Gross <colesb...@gmail.com>
committer: colesbury <colesb...@gmail.com>
date: 2025-02-27T13:27:54Z
summary:
gh-130421: Fix data race on timebase initialization (gh-130592)
Windows and macOS require precomputing a "timebase" in order to convert
OS timestamps into nanoseconds. Retrieve and compute this value during
runtime initialization to avoid data races when accessing the time.
files:
M Include/internal/pycore_runtime.h
M Include/internal/pycore_time.h
M Python/pystate.c
M Python/pytime.c
diff --git a/Include/internal/pycore_runtime.h
b/Include/internal/pycore_runtime.h
index cf123791eba9ac..9324ce9eb89d2c 100644
--- a/Include/internal/pycore_runtime.h
+++ b/Include/internal/pycore_runtime.h
@@ -23,6 +23,7 @@ extern "C" {
#include "pycore_pymem.h" // struct _pymem_allocators
#include "pycore_pythread.h" // struct _pythread_runtime_state
#include "pycore_signal.h" // struct _signals_runtime_state
+#include "pycore_time.h" // struct _PyTime_runtime_state
#include "pycore_tracemalloc.h" // struct _tracemalloc_runtime_state
#include "pycore_typeobject.h" // struct _types_runtime_state
#include "pycore_unicodeobject.h" // struct _Py_unicode_runtime_state
@@ -168,6 +169,7 @@ typedef struct pyruntimestate {
struct _Py_float_runtime_state float_state;
struct _Py_unicode_runtime_state unicode_state;
struct _types_runtime_state types;
+ struct _Py_time_runtime_state time;
#if defined(__EMSCRIPTEN__) && defined(PY_CALL_TRAMPOLINE)
// Used in "Python/emscripten_trampoline.c" to choose between type
diff --git a/Include/internal/pycore_time.h b/Include/internal/pycore_time.h
index 205ac5d3781ddd..833987fd639344 100644
--- a/Include/internal/pycore_time.h
+++ b/Include/internal/pycore_time.h
@@ -331,6 +331,18 @@ extern double _PyTimeFraction_Resolution(
const _PyTimeFraction *frac);
+// --- _Py_time_runtime_state ------------------------------------------------
+
+struct _Py_time_runtime_state {
+#if defined(MS_WINDOWS) || defined(__APPLE__)
+ _PyTimeFraction base;
+#else
+ char _unused;
+#endif
+};
+
+extern PyStatus _PyTime_Init(struct _Py_time_runtime_state *state);
+
#ifdef __cplusplus
}
#endif
diff --git a/Python/pystate.c b/Python/pystate.c
index 09b83cdeb1f42d..9ebd9fdea60746 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -20,6 +20,7 @@
#include "pycore_pystate.h"
#include "pycore_runtime_init.h" // _PyRuntimeState_INIT
#include "pycore_stackref.h" // Py_STACKREF_DEBUG
+#include "pycore_time.h" // _PyTime_Init()
#include "pycore_obmalloc.h" // _PyMem_obmalloc_state_on_heap()
#include "pycore_uniqueid.h" // _PyObject_FinalizePerThreadRefcounts()
@@ -461,6 +462,11 @@ _PyRuntimeState_Init(_PyRuntimeState *runtime)
assert(!runtime->_initialized);
}
+ PyStatus status = _PyTime_Init(&runtime->time);
+ if (_PyStatus_EXCEPTION(status)) {
+ return status;
+ }
+
if (gilstate_tss_init(runtime) != 0) {
_PyRuntimeState_Fini(runtime);
return _PyStatus_NO_MEMORY();
diff --git a/Python/pytime.c b/Python/pytime.c
index c039fc98ce4bde..b10d5cf927b7e1 100644
--- a/Python/pytime.c
+++ b/Python/pytime.c
@@ -1,4 +1,5 @@
#include "Python.h"
+#include "pycore_initconfig.h" // _PyStatus_ERR
#include "pycore_time.h" // PyTime_t
#include "pycore_pystate.h" // _Py_AssertHoldsTstate()
@@ -56,14 +57,6 @@
#endif
-#ifdef MS_WINDOWS
-static _PyTimeFraction py_qpc_base = {0, 0};
-
-// Forward declaration
-static int py_win_perf_counter_frequency(_PyTimeFraction *base, int raise_exc);
-#endif
-
-
static PyTime_t
_PyTime_GCD(PyTime_t x, PyTime_t y)
{
@@ -923,15 +916,9 @@ py_get_system_clock(PyTime_t *tp, _Py_clock_info_t *info,
int raise_exc)
if (info) {
// GetSystemTimePreciseAsFileTime() is implemented using
// QueryPerformanceCounter() internally.
- if (py_qpc_base.denom == 0) {
- if (py_win_perf_counter_frequency(&py_qpc_base, raise_exc) < 0) {
- return -1;
- }
- }
-
info->implementation = "GetSystemTimePreciseAsFileTime()";
info->monotonic = 0;
- info->resolution = _PyTimeFraction_Resolution(&py_qpc_base);
+ info->resolution = _PyTimeFraction_Resolution(&_PyRuntime.time.base);
info->adjustable = 1;
}
@@ -1043,8 +1030,8 @@ _PyTime_TimeWithInfo(PyTime_t *t, _Py_clock_info_t *info)
#ifdef MS_WINDOWS
-static int
-py_win_perf_counter_frequency(_PyTimeFraction *base, int raise_exc)
+static PyStatus
+py_win_perf_counter_frequency(_PyTimeFraction *base)
{
LARGE_INTEGER freq;
// Since Windows XP, the function cannot fail.
@@ -1062,13 +1049,9 @@ py_win_perf_counter_frequency(_PyTimeFraction *base, int
raise_exc)
// * 10,000,000 (10 MHz): 100 ns resolution
// * 3,579,545 Hz (3.6 MHz): 279 ns resolution
if (_PyTimeFraction_Set(base, SEC_TO_NS, denom) < 0) {
- if (raise_exc) {
- PyErr_SetString(PyExc_RuntimeError,
- "invalid QueryPerformanceFrequency");
- }
- return -1;
+ return _PyStatus_ERR("invalid QueryPerformanceFrequency");
}
- return 0;
+ return PyStatus_Ok();
}
@@ -1078,15 +1061,9 @@ py_get_win_perf_counter(PyTime_t *tp, _Py_clock_info_t
*info, int raise_exc)
{
assert(info == NULL || raise_exc);
- if (py_qpc_base.denom == 0) {
- if (py_win_perf_counter_frequency(&py_qpc_base, raise_exc) < 0) {
- return -1;
- }
- }
-
if (info) {
info->implementation = "QueryPerformanceCounter()";
- info->resolution = _PyTimeFraction_Resolution(&py_qpc_base);
+ info->resolution = _PyTimeFraction_Resolution(&_PyRuntime.time.base);
info->monotonic = 1;
info->adjustable = 0;
}
@@ -1102,15 +1079,15 @@ py_get_win_perf_counter(PyTime_t *tp, _Py_clock_info_t
*info, int raise_exc)
"LONGLONG is larger than PyTime_t");
ticks = (PyTime_t)ticksll;
- *tp = _PyTimeFraction_Mul(ticks, &py_qpc_base);
+ *tp = _PyTimeFraction_Mul(ticks, &_PyRuntime.time.base);
return 0;
}
#endif // MS_WINDOWS
#ifdef __APPLE__
-static int
-py_mach_timebase_info(_PyTimeFraction *base, int raise_exc)
+static PyStatus
+py_mach_timebase_info(_PyTimeFraction *base)
{
mach_timebase_info_data_t timebase;
// According to the Technical Q&A QA1398, mach_timebase_info() cannot
@@ -1132,16 +1109,23 @@ py_mach_timebase_info(_PyTimeFraction *base, int
raise_exc)
// * (1000000000, 33333335) on PowerPC: ~30 ns
// * (1000000000, 25000000) on PowerPC: 40 ns
if (_PyTimeFraction_Set(base, numer, denom) < 0) {
- if (raise_exc) {
- PyErr_SetString(PyExc_RuntimeError,
- "invalid mach_timebase_info");
- }
- return -1;
+ return _PyStatus_ERR("invalid mach_timebase_info");
}
- return 0;
+ return PyStatus_Ok();
}
#endif
+PyStatus
+_PyTime_Init(struct _Py_time_runtime_state *state)
+{
+#ifdef MS_WINDOWS
+ return py_win_perf_counter_frequency(&state->base);
+#elif defined(__APPLE__)
+ return py_mach_timebase_info(&state->base);
+#else
+ return PyStatus_Ok();
+#endif
+}
// N.B. If raise_exc=0, this may be called without a thread state.
static int
@@ -1158,16 +1142,9 @@ py_get_monotonic_clock(PyTime_t *tp, _Py_clock_info_t
*info, int raise_exc)
return -1;
}
#elif defined(__APPLE__)
- static _PyTimeFraction base = {0, 0};
- if (base.denom == 0) {
- if (py_mach_timebase_info(&base, raise_exc) < 0) {
- return -1;
- }
- }
-
if (info) {
info->implementation = "mach_absolute_time()";
- info->resolution = _PyTimeFraction_Resolution(&base);
+ info->resolution = _PyTimeFraction_Resolution(&_PyRuntime.time.base);
info->monotonic = 1;
info->adjustable = 0;
}
@@ -1177,7 +1154,7 @@ py_get_monotonic_clock(PyTime_t *tp, _Py_clock_info_t
*info, int raise_exc)
assert(uticks <= (uint64_t)PyTime_MAX);
PyTime_t ticks = (PyTime_t)uticks;
- PyTime_t ns = _PyTimeFraction_Mul(ticks, &base);
+ PyTime_t ns = _PyTimeFraction_Mul(ticks, &_PyRuntime.time.base);
*tp = ns;
#elif defined(__hpux)
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