gh-117435: Make `SemLock` thread-safe in free-threaded build (#117436)

Use critical sections to make acquire, release, and _count thread-safe
without the GIL.

diff --git a/Modules/_multiprocessing/clinic/semaphore.c.h b/Modules/_multiprocessing/clinic/semaphore.c.h
index 7c855113113c20e771e5de948b53e84614b4e42c..64e666b5af6f5bdec02920c9725b0ca826b15f41 100644 (file)
--- a/Modules/_multiprocessing/clinic/semaphore.c.h
+++ b/Modules/_multiprocessing/clinic/semaphore.c.h
@@ -6,6 +6,7 @@ preserve
 #  include "pycore_gc.h"          // PyGC_Head
 #  include "pycore_runtime.h"     // _Py_ID()
 #endif
+#include "pycore_critical_section.h"// Py_BEGIN_CRITICAL_SECTION()
 #include "pycore_modsupport.h"    // _PyArg_UnpackKeywords()
 
 #if defined(HAVE_MP_SEMAPHORE) && defined(MS_WINDOWS)
@@ -75,7 +76,9 @@ _multiprocessing_SemLock_acquire(SemLockObject *self, PyObject *const *args, Py_
     }
     timeout_obj = args[1];
 skip_optional_pos:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _multiprocessing_SemLock_acquire_impl(self, blocking, timeout_obj);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -100,7 +103,13 @@ _multiprocessing_SemLock_release_impl(SemLockObject *self);
 static PyObject *
 _multiprocessing_SemLock_release(SemLockObject *self, PyObject *Py_UNUSED(ignored))
 {
-    return _multiprocessing_SemLock_release_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _multiprocessing_SemLock_release_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 #endif /* defined(HAVE_MP_SEMAPHORE) && defined(MS_WINDOWS) */
@@ -172,7 +181,9 @@ _multiprocessing_SemLock_acquire(SemLockObject *self, PyObject *const *args, Py_
     }
     timeout_obj = args[1];
 skip_optional_pos:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _multiprocessing_SemLock_acquire_impl(self, blocking, timeout_obj);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -197,7 +208,13 @@ _multiprocessing_SemLock_release_impl(SemLockObject *self);
 static PyObject *
 _multiprocessing_SemLock_release(SemLockObject *self, PyObject *Py_UNUSED(ignored))
 {
-    return _multiprocessing_SemLock_release_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _multiprocessing_SemLock_release_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 #endif /* defined(HAVE_MP_SEMAPHORE) && !defined(MS_WINDOWS) */
@@ -340,7 +357,13 @@ _multiprocessing_SemLock__count_impl(SemLockObject *self);
 static PyObject *
 _multiprocessing_SemLock__count(SemLockObject *self, PyObject *Py_UNUSED(ignored))
 {
-    return _multiprocessing_SemLock__count_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _multiprocessing_SemLock__count_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 #endif /* defined(HAVE_MP_SEMAPHORE) */
@@ -542,4 +565,4 @@ exit:
 #ifndef _MULTIPROCESSING_SEMLOCK___EXIT___METHODDEF
     #define _MULTIPROCESSING_SEMLOCK___EXIT___METHODDEF
 #endif /* !defined(_MULTIPROCESSING_SEMLOCK___EXIT___METHODDEF) */
-/*[clinic end generated code: output=d57992037e6770b6 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=713b597256233716 input=a9049054013a1b77]*/

diff --git a/Modules/_multiprocessing/semaphore.c b/Modules/_multiprocessing/semaphore.c
index f8f2afda28d06dbc58ef1228836f87ba1575700b..5bb055f501e35b10ff5f477ae4a124ef43faee3a 100644 (file)
--- a/Modules/_multiprocessing/semaphore.c
+++ b/Modules/_multiprocessing/semaphore.c
@@ -81,6 +81,7 @@ _GetSemaphoreValue(HANDLE handle, long *value)
 }
 
 /*[clinic input]
+@critical_section
 _multiprocessing.SemLock.acquire
 
     block as blocking: bool = True
@@ -92,7 +93,7 @@ Acquire the semaphore/lock.
 static PyObject *
 _multiprocessing_SemLock_acquire_impl(SemLockObject *self, int blocking,
                                       PyObject *timeout_obj)
-/*[clinic end generated code: output=f9998f0b6b0b0872 input=e5b45f5cbb775166]*/
+/*[clinic end generated code: output=f9998f0b6b0b0872 input=079ca779975f3ad6]*/
 {
     double timeout;
     DWORD res, full_msecs, nhandles;
@@ -172,6 +173,7 @@ _multiprocessing_SemLock_acquire_impl(SemLockObject *self, int blocking,
 }
 
 /*[clinic input]
+@critical_section
 _multiprocessing.SemLock.release
 
 Release the semaphore/lock.
@@ -179,7 +181,7 @@ Release the semaphore/lock.
 
 static PyObject *
 _multiprocessing_SemLock_release_impl(SemLockObject *self)
-/*[clinic end generated code: output=b22f53ba96b0d1db input=ba7e63a961885d3d]*/
+/*[clinic end generated code: output=b22f53ba96b0d1db input=9bd62d3645e7a531]*/
 {
     if (self->kind == RECURSIVE_MUTEX) {
         if (!ISMINE(self)) {
@@ -297,6 +299,7 @@ sem_timedwait_save(sem_t *sem, struct timespec *deadline, PyThreadState *_save)
 #endif /* !HAVE_SEM_TIMEDWAIT */
 
 /*[clinic input]
+@critical_section
 _multiprocessing.SemLock.acquire
 
     block as blocking: bool = True
@@ -308,7 +311,7 @@ Acquire the semaphore/lock.
 static PyObject *
 _multiprocessing_SemLock_acquire_impl(SemLockObject *self, int blocking,
                                       PyObject *timeout_obj)
-/*[clinic end generated code: output=f9998f0b6b0b0872 input=e5b45f5cbb775166]*/
+/*[clinic end generated code: output=f9998f0b6b0b0872 input=079ca779975f3ad6]*/
 {
     int res, err = 0;
     struct timespec deadline = {0};
@@ -382,6 +385,7 @@ _multiprocessing_SemLock_acquire_impl(SemLockObject *self, int blocking,
 }
 
 /*[clinic input]
+@critical_section
 _multiprocessing.SemLock.release
 
 Release the semaphore/lock.
@@ -389,7 +393,7 @@ Release the semaphore/lock.
 
 static PyObject *
 _multiprocessing_SemLock_release_impl(SemLockObject *self)
-/*[clinic end generated code: output=b22f53ba96b0d1db input=ba7e63a961885d3d]*/
+/*[clinic end generated code: output=b22f53ba96b0d1db input=9bd62d3645e7a531]*/
 {
     if (self->kind == RECURSIVE_MUTEX) {
         if (!ISMINE(self)) {
@@ -583,6 +587,7 @@ semlock_dealloc(SemLockObject* self)
 }
 
 /*[clinic input]
+@critical_section
 _multiprocessing.SemLock._count
 
 Num of `acquire()`s minus num of `release()`s for this process.
@@ -590,7 +595,7 @@ Num of `acquire()`s minus num of `release()`s for this process.
 
 static PyObject *
 _multiprocessing_SemLock__count_impl(SemLockObject *self)
-/*[clinic end generated code: output=5ba8213900e517bb input=36fc59b1cd1025ab]*/
+/*[clinic end generated code: output=5ba8213900e517bb input=9fa6e0b321b16935]*/
 {
     return PyLong_FromLong((long)self->count);
 }