From e0e0029623248e6ed786df91c3cdf9ff4f283d32 Mon Sep 17 00:00:00 2001
From: Antoine Pitrou <pitrou@free.fr>
Date: Tue, 13 Jun 2017 10:21:54 +0200
Subject: [PATCH] [3.5] Mention how to disable signal fd wakeup (GH-2140)
 (#2150)

(cherry picked from commit d79c1d4a9406384f10a37f26a7515ce79f9fdd78)
---
 Doc/library/signal.rst | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst
index 039b666475a247..46d71def08abd6 100644
--- a/Doc/library/signal.rst
+++ b/Doc/library/signal.rst
@@ -306,8 +306,10 @@ The :mod:`signal` module defines the following functions:
    a library to wakeup a poll or select call, allowing the signal to be fully
    processed.
 
-   The old wakeup fd is returned.  *fd* must be non-blocking.  It is up to the
-   library to remove any bytes before calling poll or select again.
+   The old wakeup fd is returned (or -1 if file descriptor wakeup was not
+   enabled).  If *fd* is -1, file descriptor wakeup is disabled.
+   If not -1, *fd* must be non-blocking.  It is up to the library to remove
+   any bytes from *fd* before calling poll or select again.
 
    Use for example ``struct.unpack('%uB' % len(data), data)`` to decode the
    signal numbers list.