Adress more code reviews

tiran · tiran · commit 9c0dff53033b · 2020-11-13T11:27:56.000+01:00
- initval is a uint32_t
- improve documentation
- add whatsnew

Signed-off-by: Christian Heimes &lt;christian@python.org&gt;
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
@@ -3283,6 +3283,14 @@ features:
    :func:`~select.select`, :func:`~select.poll` and similar. By default, the
    new file descriptor is :ref:`non-inheritable <fd_inheritance>`.
 
+   *initval* is the initial value of the event counter. The initial value
+   must be an 32 bit unsigned integer. Please note that the initial value is
+   limited to a 32 bit unsigned int although the event counter is an unsigned
+   64 bit integer with a maximum value of 2\ :sup:`64`\ -\ 2.
+
+   *flags* can be constructed from :const:`EFD_CLOEXEC`,
+   :const:`EFD_NONBLOCK`, and :const:`EFD_SEMAPHORE`.
+
    If :const:`EFD_SEMAPHORE` is specified and the event counter is non-zero,
    :func:`eventfd_read` returns 1 and decrements the counter by one.
 
@@ -3292,53 +3300,55 @@ features:
 
    If the event counter is zero, :func:`eventfd_read` blocks.
 
-   :func:`eventfd_write` increments the event counter.
-
-   *initval* is the initial value of the event counter. It must be an
-   unsigned integer between 0 and 2\ :sup:`64`\ -\ 2.
-
-   *flags* can be constructed from :const:`EFD_CLOEXEC`,
-   :const:`EFD_NONBLOCK`, and :const:`EFD_SEMAPHORE`.
+   :func:`eventfd_write` increments the event counter. Write blocks if the
+   write operation would increment the counter to a value larger than
+   2\ :sup:`64`\ -\ 2.
 
    .. availability:: Linux 2.6.27 or newer with glibc 2.8 or newer.
 
    .. versionadded:: 3.10
 
 .. function:: eventfd_read(fd)
 
-   Read value from an :func:`eventfd` file descriptor and return
-   an unsigned integer between 0 and 2\ :sup:`64`\ -\ 2. The function does
-   not verify that *fd* is an :func:`eventfd`.
+   Read value from an :func:`eventfd` file descriptor and return a 64 bit
+   unsigned int. The function does not verify that *fd* is an :func:`eventfd`.
+
+   .. availability:: See :func:`eventfd`
 
    .. versionadded:: 3.10
 
 .. function:: eventfd_write(fd, value)
 
-   Add value to an :func:`eventfd` file descriptor. *value* must be
-   an unsigned integer between 0 and 2\ :sup:`64`\ -\ 2. The function does
-   not verify that *fd* is an :func:`eventfd`.
+   Add value to an :func:`eventfd` file descriptor. *value* must be a 64 bit
+   unsigned int. The function does not verify that *fd* is an :func:`eventfd`.
+
+   .. availability:: See :func:`eventfd`
 
    .. versionadded:: 3.10
 
 .. data:: EFD_CLOEXEC
 
    Set close-on-exec flag for new :func:`eventfd` file descriptor.
 
+   .. availability:: See :func:`eventfd`
+
    .. versionadded:: 3.10
 
 .. data:: EFD_NONBLOCK
 
    Set :const:`O_NONBLOCK` status flag for new :func:`eventfd` file
    descriptor.
 
+   .. availability:: See :func:`eventfd`
+
    .. versionadded:: 3.10
 
 .. data:: EFD_SEMAPHORE
 
    Provide semaphore-like semantics for reads from a :func:`eventfd` file
    descriptor. On read the internal counter is decremented by one.
 
-   .. availability:: Linux 2.6.30 or newer
+   .. availability:: Linux 2.6.30 or newer with glibc 2.8 or newer.
 
    .. versionadded:: 3.10
 
diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
@@ -229,6 +229,10 @@ os
 Added :func:`os.cpu_count()` support for VxWorks RTOS.
 (Contributed by Peixing Xin in :issue:`41440`.)
 
+A new :func:`os.eventfd` function and related helpers were added to wrap the
+``eventfd2`` syscall on Linux
+(Contributed by Christian Heimes in :issue:`41001`.)
+
 py_compile
 ----------
 
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
@@ -12877,12 +12877,10 @@ Creates and returns an event notification file descriptor.
 static PyObject *
 os_eventfd_impl(PyObject *module, unsigned int initval, int flags)
 /*[clinic end generated code: output=ce9c9bbd1446f2de input=66203e3c50c4028b]*/
+
 {
+    /* initval is limited to uint32_t, internal counter is uint64_t */
     int fd;
-    if (initval > (PY_ULLONG_MAX - 1)) {
-        PyErr_SetString(PyExc_OverflowError, "initval too large");
-        return NULL;
-    }
     Py_BEGIN_ALLOW_THREADS
     fd = eventfd(initval, flags);
     Py_END_ALLOW_THREADS
@@ -12921,18 +12919,14 @@ os.eventfd_write
     fd: fildes
     value: unsigned_long_long
 
-Write eventfd value
+Write eventfd value.
 [clinic start generated code]*/
 
 static PyObject *
 os_eventfd_write_impl(PyObject *module, int fd, unsigned long long value)
-/*[clinic end generated code: output=bebd9040bbf987f5 input=82da3dd0d6e62f28]*/
+/*[clinic end generated code: output=bebd9040bbf987f5 input=156de8555be5a949]*/
 {
     int result;
-    if (value > (PY_ULLONG_MAX - 1)) {
-        PyErr_SetString(PyExc_OverflowError, "value too large");
-        return NULL;
-    }
     Py_BEGIN_ALLOW_THREADS
     result = eventfd_write(fd, value);
     Py_END_ALLOW_THREADS
