udev: improve udev-cache robustness

 * allow udev-cache to be disabled at runtime (using
   /etc/default/udev-cache);

 * make cache invalidated if kernel, bootparams or device list
   changes;

(From OE-Core rev: 22b72b23653736436f10d394de36201c32630d5d)

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 30 insertions, 3 deletions

diff --git a/meta/recipes-core/udev/udev/init b/meta/recipes-core/udev/udev/init
index 6a4464c639..78b5b1c4b6 100644
--- a/meta/recipes-core/udev/udev/init
+++ b/meta/recipes-core/udev/udev/init
@@ -14,8 +14,19 @@ export TZ=/etc/localtime
 [ -d /sys/class ] || exit 1
 [ -r /proc/mounts ] || exit 1
 [ -x /sbin/udevd ] || exit 1
+[ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 [ -f /etc/udev/udev.conf ] && . /etc/udev/udev.conf
 
+readfile () {
+   filename=$1
+   READDATA=""
+   if [ -r $filename ]; then
+       while read line; do
+           READDATA="$READDATA$line"
+       done < $filename
+   fi
+}
+
 kill_udevd() {
         if [ -x /sbin/pidof ]; then
                 pid=`/sbin/pidof -x udevd`
@@ -34,10 +45,26 @@ LANG=C awk '$2 == "/dev" && ($3 == "tmpfs" || $3 == "devtmpfs") { exit 1 }' /pro
 [ -e /dev/pts ] || mkdir -m 0755 /dev/pts
 [ -e /dev/shm ] || mkdir -m 1777 /dev/shm
 
+# cache handling
+if [ "$DEVCACHE" != "" ]; then
+        readfile /proc/version
+        VERSION="$READDATA"
+        readfile /proc/cmdline
+        CMDLINE="$READDATA"
+        readfile /proc/devices
+        DEVICES="$READDATA"
+        readfile /proc/atags
+        ATAGS="$READDATA"
 
-if [ -e /etc/dev.tar ]; then
-        (cd /; tar xf /etc/dev.tar 2>&1 | grep -v 'time stamp' || true)
-        not_first_boot=1
+        if [ -e $DEVCACHE ]; then
+                readfile /etc/udev/cache.data
+                if [ "$READDATA" = "$VERSION$CMDLINE$DEVICES$ATAGS" ]; then
+                        (cd /; tar xf $DEVCACHE > /dev/null 2>&1)
+                        not_first_boot=1
+                fi
+
+                echo "$VERSION$CMDLINE$DEVICES$ATAGS" > /dev/shm/udev.cache
+        fi
 fi
 
 # make_extra_nodes