commit 4984f1442b39f2a2f0f9244e20648b840fd66b8e
Author: Sam Thursfield <sam.thursfield@codethink.co.uk>
Date:   Mon Jun 18 12:36:37 2012 +0100

    libudev: Fix documentation for udev_monitor_receive_device()

diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c
index 32319ac..82dbdf4 100644
--- a/src/libudev/libudev-monitor.c
+++ b/src/libudev/libudev-monitor.c
@@ -492,6 +492,13 @@ tag:
  * Receive data from the udev monitor socket, allocate a new udev
  * device, fill in the received data, and return the device.
  *
+ * It is an error to call this function if there is no data available.
+ * The function will return #NULL in this case. You should monitor the
+ * file handle returned by udev_monitor_get_fd() to ensure data is available
+ * before calling. Note that the behaviour of this function changed in
+ * libudev 171. Code that assumes this function will block should be changed
+ * to use poll().
+ *
  * Only socket connections with uid=0 are accepted.
  *
  * The initial refcount is 1, and needs to be decremented to