From bf88c6ef54608f4488fca806b5f30afad08d6c51 Mon Sep 17 00:00:00 2001
From: Scott Moser <smoser@ubuntu.com>
Date: Mon, 28 Mar 2016 14:47:19 -0400
Subject: improve how cloud-init-wait waits

since we run from a udev event, this is sufficient.
udev settle will exit when either of
 a.) the file exists
 b.) the udev event queue has all been processed.

Since cloud-init-wait is being run as a udev event, 'b' cannot
be satisfied until it finishes.  Thus, this essentially becomes a
inotify based wait for the file /run/cloud-init/network-config-ready
and no loops are needed.
---
 udev/cloud-init-wait | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/udev/cloud-init-wait b/udev/cloud-init-wait
index 7d53dee4..9df502e3 100755
--- a/udev/cloud-init-wait
+++ b/udev/cloud-init-wait
@@ -3,16 +3,13 @@
 CI_NET_READY="/run/cloud-init/network-config-ready"
 LOG="/run/cloud-init/${0##*/}.log"
 LOG_INIT=0
+MAX_WAIT=60
 DEBUG=0
 
 block_until_ready() {
-    local fname="$1"
-    local naplen="$2" max="$3" n=0
-    while ! [ -f "$fname" ]; do
-        n=$(($n+1))
-        [ "$n" -ge "$max" ] && return 1
-        sleep $naplen
-    done
+    local fname="$1" max="$2"
+    [ -f "$fname" ] && return 0
+    udevadm settle "--timeout=$max" "--exit-if-exists=$fname"
 }
 
 log() {
@@ -56,7 +53,7 @@ main() {
         return 0
     fi
 
-    block_until_ready "$readyfile" .1 600 ||
+    block_until_ready "$readyfile" "$MAX_WAIT" ||
        { log "failed waiting for ready on $INTERFACE"; return 1; }
 
     log "net config ready"
-- 
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