gh-111965: Use critical sections to make io.BufferedIOBase and its related classes thread safe (gh-112298)

2 files changed, 180 insertions, 40 deletions

diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index d7123ab..4f37866 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -8,11 +8,12 @@
 */
 
 #include "Python.h"
-#include "pycore_bytesobject.h"   // _PyBytes_Join()
-#include "pycore_call.h"          // _PyObject_CallNoArgs()
-#include "pycore_object.h"        // _PyObject_GC_UNTRACK()
-#include "pycore_pyerrors.h"      // _Py_FatalErrorFormat()
-#include "pycore_pylifecycle.h"   // _Py_IsInterpreterFinalizing()
+#include "pycore_bytesobject.h"         // _PyBytes_Join()
+#include "pycore_call.h"                // _PyObject_CallNoArgs()
+#include "pycore_critical_section.h"    // Py_BEGIN_CRITICAL_SECTION()
+#include "pycore_object.h"              // _PyObject_GC_UNTRACK()
+#include "pycore_pyerrors.h"            // _Py_FatalErrorFormat()
+#include "pycore_pylifecycle.h"         // _Py_IsInterpreterFinalizing()
 
 #include "_iomodule.h"
 
@@ -82,6 +83,7 @@ _bufferediobase_readinto_generic(PyObject *self, Py_buffer *buffer, char readint
 }
 
 /*[clinic input]
+@critical_section
 _io._BufferedIOBase.readinto
     buffer: Py_buffer(accept={rwbuffer})
     /
@@ -89,12 +91,13 @@ _io._BufferedIOBase.readinto
 
 static PyObject *
 _io__BufferedIOBase_readinto_impl(PyObject *self, Py_buffer *buffer)
-/*[clinic end generated code: output=8c8cda6684af8038 input=00a6b9a38f29830a]*/
+/*[clinic end generated code: output=8c8cda6684af8038 input=5273d20db7f56e1a]*/
 {
     return _bufferediobase_readinto_generic(self, buffer, 0);
 }
 
 /*[clinic input]
+@critical_section
 _io._BufferedIOBase.readinto1
     buffer: Py_buffer(accept={rwbuffer})
     /
@@ -102,7 +105,7 @@ _io._BufferedIOBase.readinto1
 
 static PyObject *
 _io__BufferedIOBase_readinto1_impl(PyObject *self, Py_buffer *buffer)
-/*[clinic end generated code: output=358623e4fd2b69d3 input=ebad75b4aadfb9be]*/
+/*[clinic end generated code: output=358623e4fd2b69d3 input=d6eb723dedcee654]*/
 {
     return _bufferediobase_readinto_generic(self, buffer, 1);
 }
@@ -431,12 +434,13 @@ buffered_dealloc(buffered *self)
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.__sizeof__
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered___sizeof___impl(buffered *self)
-/*[clinic end generated code: output=0231ef7f5053134e input=753c782d808d34df]*/
+/*[clinic end generated code: output=0231ef7f5053134e input=07a32d578073ea64]*/
 {
     size_t res = _PyObject_SIZE(Py_TYPE(self));
     if (self->buffer) {
@@ -488,12 +492,13 @@ _io__Buffered__dealloc_warn(buffered *self, PyObject *source)
 
 /* Flush and close */
 /*[clinic input]
+@critical_section
 _io._Buffered.flush as _io__Buffered_simple_flush
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_simple_flush_impl(buffered *self)
-/*[clinic end generated code: output=29ebb3820db1bdfd input=f33ef045e7250767]*/
+/*[clinic end generated code: output=29ebb3820db1bdfd input=5248cb84a65f80bd]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(flush));
@@ -514,12 +519,24 @@ buffered_closed(buffered *self)
 }
 
 static PyObject *
-buffered_closed_get(buffered *self, void *context)
+buffered_closed_get_impl(buffered *self, void *context)
 {
     CHECK_INITIALIZED(self)
     return PyObject_GetAttr(self->raw, &_Py_ID(closed));
 }
 
+static PyObject *
+buffered_closed_get(buffered *self, void *context)
+{
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = buffered_closed_get_impl(self, context);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
+}
+
 /*[clinic input]
 @critical_section
 _io._Buffered.close
@@ -584,12 +601,13 @@ end:
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.detach
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_detach_impl(buffered *self)
-/*[clinic end generated code: output=dd0fc057b8b779f7 input=482762a345cc9f44]*/
+/*[clinic end generated code: output=dd0fc057b8b779f7 input=d4ef1828a678be37]*/
 {
     PyObject *raw;
     CHECK_INITIALIZED(self)
@@ -606,76 +624,105 @@ _io__Buffered_detach_impl(buffered *self)
 /* Inquiries */
 
 /*[clinic input]
+@critical_section
 _io._Buffered.seekable
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_seekable_impl(buffered *self)
-/*[clinic end generated code: output=90172abb5ceb6e8f input=7d35764f5fb5262b]*/
+/*[clinic end generated code: output=90172abb5ceb6e8f input=e3a4fc1d297b2fd3]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(seekable));
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.readable
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_readable_impl(buffered *self)
-/*[clinic end generated code: output=92afa07661ecb698 input=640619addb513b8b]*/
+/*[clinic end generated code: output=92afa07661ecb698 input=abe54107d59bca9a]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(readable));
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.writable
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_writable_impl(buffered *self)
-/*[clinic end generated code: output=4e3eee8d6f9d8552 input=b35ea396b2201554]*/
+/*[clinic end generated code: output=4e3eee8d6f9d8552 input=45eb76bf6a10e6f7]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(writable));
 }
 
 static PyObject *
-buffered_name_get(buffered *self, void *context)
+buffered_name_get_impl(buffered *self, void *context)
 {
     CHECK_INITIALIZED(self)
     return PyObject_GetAttr(self->raw, &_Py_ID(name));
 }
 
 static PyObject *
-buffered_mode_get(buffered *self, void *context)
+buffered_name_get(buffered *self, void *context)
+{
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = buffered_name_get_impl(self, context);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
+}
+
+static PyObject *
+buffered_mode_get_impl(buffered *self, void *context)
 {
     CHECK_INITIALIZED(self)
     return PyObject_GetAttr(self->raw, &_Py_ID(mode));
 }
 
+static PyObject *
+buffered_mode_get(buffered *self, void *context)
+{
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = buffered_mode_get_impl(self, context);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
+}
+
 /* Lower-level APIs */
 
 /*[clinic input]
+@critical_section
 _io._Buffered.fileno
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_fileno_impl(buffered *self)
-/*[clinic end generated code: output=b717648d58a95ee3 input=768ea30b3f6314a7]*/
+/*[clinic end generated code: output=b717648d58a95ee3 input=1c4fead777bae20a]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(fileno));
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.isatty
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_isatty_impl(buffered *self)
-/*[clinic end generated code: output=c20e55caae67baea input=9ea007b11559bee4]*/
+/*[clinic end generated code: output=c20e55caae67baea input=e53d182d7e490e3a]*/
 {
     CHECK_INITIALIZED(self)
     return PyObject_CallMethodNoArgs(self->raw, &_Py_ID(isatty));
@@ -881,12 +928,13 @@ buffered_flush_and_rewind_unlocked(buffered *self)
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.flush
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_flush_impl(buffered *self)
-/*[clinic end generated code: output=da2674ef1ce71f3a input=fda63444697c6bf4]*/
+/*[clinic end generated code: output=da2674ef1ce71f3a input=6b30de9f083419c2]*/
 {
     PyObject *res;
 
@@ -902,6 +950,7 @@ _io__Buffered_flush_impl(buffered *self)
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.peek
     size: Py_ssize_t = 0
     /
@@ -910,7 +959,7 @@ _io._Buffered.peek
 
 static PyObject *
 _io__Buffered_peek_impl(buffered *self, Py_ssize_t size)
-/*[clinic end generated code: output=ba7a097ca230102b input=37ffb97d06ff4adb]*/
+/*[clinic end generated code: output=ba7a097ca230102b input=56733376f926d982]*/
 {
     PyObject *res = NULL;
 
@@ -934,6 +983,7 @@ end:
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.read
     size as n: Py_ssize_t(accept={int, NoneType}) = -1
     /
@@ -941,7 +991,7 @@ _io._Buffered.read
 
 static PyObject *
 _io__Buffered_read_impl(buffered *self, Py_ssize_t n)
-/*[clinic end generated code: output=f41c78bb15b9bbe9 input=7df81e82e08a68a2]*/
+/*[clinic end generated code: output=f41c78bb15b9bbe9 input=bdb4b0425b295472]*/
 {
     PyObject *res;
 
@@ -975,6 +1025,7 @@ _io__Buffered_read_impl(buffered *self, Py_ssize_t n)
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.read1
     size as n: Py_ssize_t = -1
     /
@@ -982,7 +1033,7 @@ _io._Buffered.read1
 
 static PyObject *
 _io__Buffered_read1_impl(buffered *self, Py_ssize_t n)
-/*[clinic end generated code: output=bcc4fb4e54d103a3 input=7d22de9630b61774]*/
+/*[clinic end generated code: output=bcc4fb4e54d103a3 input=3d0ad241aa52b36c]*/
 {
     Py_ssize_t have, r;
     PyObject *res = NULL;
@@ -1111,6 +1162,7 @@ end:
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.readinto
     buffer: Py_buffer(accept={rwbuffer})
     /
@@ -1118,12 +1170,13 @@ _io._Buffered.readinto
 
 static PyObject *
 _io__Buffered_readinto_impl(buffered *self, Py_buffer *buffer)
-/*[clinic end generated code: output=bcb376580b1d8170 input=ed6b98b7a20a3008]*/
+/*[clinic end generated code: output=bcb376580b1d8170 input=777c33e7adaa2bcd]*/
 {
     return _buffered_readinto_generic(self, buffer, 0);
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.readinto1
     buffer: Py_buffer(accept={rwbuffer})
     /
@@ -1131,7 +1184,7 @@ _io._Buffered.readinto1
 
 static PyObject *
 _io__Buffered_readinto1_impl(buffered *self, Py_buffer *buffer)
-/*[clinic end generated code: output=6e5c6ac5868205d6 input=4455c5d55fdf1687]*/
+/*[clinic end generated code: output=6e5c6ac5868205d6 input=ef03cc5fc92a6895]*/
 {
     return _buffered_readinto_generic(self, buffer, 1);
 }
@@ -1246,6 +1299,7 @@ end_unlocked:
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.readline
     size: Py_ssize_t(accept={int, NoneType}) = -1
     /
@@ -1253,7 +1307,7 @@ _io._Buffered.readline
 
 static PyObject *
 _io__Buffered_readline_impl(buffered *self, Py_ssize_t size)
-/*[clinic end generated code: output=24dd2aa6e33be83c input=673b6240e315ef8a]*/
+/*[clinic end generated code: output=24dd2aa6e33be83c input=e81ca5abd4280776]*/
 {
     CHECK_INITIALIZED(self)
     return _buffered_readline(self, size);
@@ -1261,12 +1315,13 @@ _io__Buffered_readline_impl(buffered *self, Py_ssize_t size)
 
 
 /*[clinic input]
+@critical_section
 _io._Buffered.tell
 [clinic start generated code]*/
 
 static PyObject *
 _io__Buffered_tell_impl(buffered *self)
-/*[clinic end generated code: output=386972ae84716c1e input=ad61e04a6b349573]*/
+/*[clinic end generated code: output=386972ae84716c1e input=ab12e67d8abcb42f]*/
 {
     Py_off_t pos;
 
@@ -1280,6 +1335,7 @@ _io__Buffered_tell_impl(buffered *self)
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.seek
     target as targetobj: object
     whence: int = 0
@@ -1288,7 +1344,7 @@ _io._Buffered.seek
 
 static PyObject *
 _io__Buffered_seek_impl(buffered *self, PyObject *targetobj, int whence)
-/*[clinic end generated code: output=7ae0e8dc46efdefb input=a9c4920bfcba6163]*/
+/*[clinic end generated code: output=7ae0e8dc46efdefb input=b5a12be70e0ad07b]*/
 {
     Py_off_t target, n;
     PyObject *res = NULL;
@@ -1377,6 +1433,7 @@ end:
 }
 
 /*[clinic input]
+@critical_section
 _io._Buffered.truncate
     cls: defining_class
     pos: object = None
@@ -1385,7 +1442,7 @@ _io._Buffered.truncate
 
 static PyObject *
 _io__Buffered_truncate_impl(buffered *self, PyTypeObject *cls, PyObject *pos)
-/*[clinic end generated code: output=fe3882fbffe79f1a input=f5b737d97d76303f]*/
+/*[clinic end generated code: output=fe3882fbffe79f1a input=e3cbf794575bd794]*/
 {
     PyObject *res = NULL;
 
@@ -1999,6 +2056,7 @@ error:
 }
 
 /*[clinic input]
+@critical_section
 _io.BufferedWriter.write
     buffer: Py_buffer
     /
@@ -2006,7 +2064,7 @@ _io.BufferedWriter.write
 
 static PyObject *
 _io_BufferedWriter_write_impl(buffered *self, Py_buffer *buffer)
-/*[clinic end generated code: output=7f8d1365759bfc6b input=dd87dd85fc7f8850]*/
+/*[clinic end generated code: output=7f8d1365759bfc6b input=6a9c041de0c337be]*/
 {
     PyObject *res = NULL;
     Py_ssize_t written, avail, remaining;
diff --git a/Modules/_io/clinic/bufferedio.c.h b/Modules/_io/clinic/bufferedio.c.h
index dd2fbb4..20833a1 100644
--- a/Modules/_io/clinic/bufferedio.c.h
+++ b/Modules/_io/clinic/bufferedio.c.h
@@ -31,7 +31,9 @@ _io__BufferedIOBase_readinto(PyObject *self, PyObject *arg)
         _PyArg_BadArgument("readinto", "argument", "read-write bytes-like object", arg);
         goto exit;
     }
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__BufferedIOBase_readinto_impl(self, &buffer);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     /* Cleanup for buffer */
@@ -63,7 +65,9 @@ _io__BufferedIOBase_readinto1(PyObject *self, PyObject *arg)
         _PyArg_BadArgument("readinto1", "argument", "read-write bytes-like object", arg);
         goto exit;
     }
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__BufferedIOBase_readinto1_impl(self, &buffer);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     /* Cleanup for buffer */
@@ -283,7 +287,13 @@ _io__Buffered___sizeof___impl(buffered *self);
 static PyObject *
 _io__Buffered___sizeof__(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered___sizeof___impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered___sizeof___impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered__dealloc_warn__doc__,
@@ -308,7 +318,13 @@ _io__Buffered_simple_flush_impl(buffered *self);
 static PyObject *
 _io__Buffered_simple_flush(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_simple_flush_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_simple_flush_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_close__doc__,
@@ -348,7 +364,13 @@ _io__Buffered_detach_impl(buffered *self);
 static PyObject *
 _io__Buffered_detach(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_detach_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_detach_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_seekable__doc__,
@@ -365,7 +387,13 @@ _io__Buffered_seekable_impl(buffered *self);
 static PyObject *
 _io__Buffered_seekable(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_seekable_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_seekable_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_readable__doc__,
@@ -382,7 +410,13 @@ _io__Buffered_readable_impl(buffered *self);
 static PyObject *
 _io__Buffered_readable(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_readable_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_readable_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_writable__doc__,
@@ -399,7 +433,13 @@ _io__Buffered_writable_impl(buffered *self);
 static PyObject *
 _io__Buffered_writable(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_writable_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_writable_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_fileno__doc__,
@@ -416,7 +456,13 @@ _io__Buffered_fileno_impl(buffered *self);
 static PyObject *
 _io__Buffered_fileno(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_fileno_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_fileno_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_isatty__doc__,
@@ -433,7 +479,13 @@ _io__Buffered_isatty_impl(buffered *self);
 static PyObject *
 _io__Buffered_isatty(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_isatty_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_isatty_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_flush__doc__,
@@ -450,7 +502,13 @@ _io__Buffered_flush_impl(buffered *self);
 static PyObject *
 _io__Buffered_flush(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_flush_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_flush_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_peek__doc__,
@@ -489,7 +547,9 @@ _io__Buffered_peek(buffered *self, PyObject *const *args, Py_ssize_t nargs)
         size = ival;
     }
 skip_optional:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_peek_impl(self, size);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -522,7 +582,9 @@ _io__Buffered_read(buffered *self, PyObject *const *args, Py_ssize_t nargs)
         goto exit;
     }
 skip_optional:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_read_impl(self, n);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -564,7 +626,9 @@ _io__Buffered_read1(buffered *self, PyObject *const *args, Py_ssize_t nargs)
         n = ival;
     }
 skip_optional:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_read1_impl(self, n);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -591,7 +655,9 @@ _io__Buffered_readinto(buffered *self, PyObject *arg)
         _PyArg_BadArgument("readinto", "argument", "read-write bytes-like object", arg);
         goto exit;
     }
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_readinto_impl(self, &buffer);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     /* Cleanup for buffer */
@@ -623,7 +689,9 @@ _io__Buffered_readinto1(buffered *self, PyObject *arg)
         _PyArg_BadArgument("readinto1", "argument", "read-write bytes-like object", arg);
         goto exit;
     }
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_readinto1_impl(self, &buffer);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     /* Cleanup for buffer */
@@ -661,7 +729,9 @@ _io__Buffered_readline(buffered *self, PyObject *const *args, Py_ssize_t nargs)
         goto exit;
     }
 skip_optional:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_readline_impl(self, size);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -681,7 +751,13 @@ _io__Buffered_tell_impl(buffered *self);
 static PyObject *
 _io__Buffered_tell(buffered *self, PyObject *Py_UNUSED(ignored))
 {
-    return _io__Buffered_tell_impl(self);
+    PyObject *return_value = NULL;
+
+    Py_BEGIN_CRITICAL_SECTION(self);
+    return_value = _io__Buffered_tell_impl(self);
+    Py_END_CRITICAL_SECTION();
+
+    return return_value;
 }
 
 PyDoc_STRVAR(_io__Buffered_seek__doc__,
@@ -714,7 +790,9 @@ _io__Buffered_seek(buffered *self, PyObject *const *args, Py_ssize_t nargs)
         goto exit;
     }
 skip_optional:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_seek_impl(self, targetobj, whence);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -760,7 +838,9 @@ _io__Buffered_truncate(buffered *self, PyTypeObject *cls, PyObject *const *args,
     }
     pos = args[0];
 skip_optional_posonly:
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io__Buffered_truncate_impl(self, cls, pos);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     return return_value;
@@ -936,7 +1016,9 @@ _io_BufferedWriter_write(buffered *self, PyObject *arg)
     if (PyObject_GetBuffer(arg, &buffer, PyBUF_SIMPLE) != 0) {
         goto exit;
     }
+    Py_BEGIN_CRITICAL_SECTION(self);
     return_value = _io_BufferedWriter_write_impl(self, &buffer);
+    Py_END_CRITICAL_SECTION();
 
 exit:
     /* Cleanup for buffer */
@@ -1082,4 +1164,4 @@ skip_optional_pos:
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=2d5f735188df3163 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=e8ad39a45531d7f2 input=a9049054013a1b77]*/