systemd: re-enable mount propagation for udevd

With MountFlags=slave, those mounts then become private to the systemd-udevd
namespace and are no longer accessible from outside the namespace, which is
not expected

(From OE-Core rev: 73f43d857fe0102033f25491007b6dbe3d5fa8ee)

Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd/udev-re-enable-mount-propagation-for-udevd.patch

@@ -0,0 +1,31 @@
+From: Michael Biebl <biebl@debian.org>
+Date: Sat, 27 Sep 2014 04:19:24 +0200
+Subject: udev: re-enable mount propagation for udevd
+
+Upstream-Status: Backport [http://http.debian.net/debian/pool/main/s/systemd/systemd_215-17+deb8u4.debian.tar.xz]
+
+laptop-mode-tools remounts file systems from within a udev rule to apply
+certain mount options. With MountFlags=slave, those mounts then become private
+to the systemd-udevd namespace and are no longer accessible from outside the
+namespace.
+While the root cause is the broken behaviour of laptop-mode-tools, with mount
+propagation turned off, this can result in a read-only root file system.
+Therefore revert the relevant parts from commit
+c2c13f2df42e0691aecabe3979ea81cd7faa35c7 to re-enable mount propagation for
+udevd.
+
+Once affected packages have been fixed, this patch should be dropped
+again.
+
+Closes: #762018
+diff --git a/units/systemd-udevd.service.in b/units/systemd-udevd.service.in
+index e7216d6..1e9a600 100644
+--- a/units/systemd-udevd.service.in
++++ b/units/systemd-udevd.service.in
+@@ -21,6 +21,5 @@ Sockets=systemd-udevd-control.socket systemd-udevd-kernel.socket
+ Restart=always
+ RestartSec=0
+ ExecStart=@rootlibexecdir@/systemd-udevd
+-MountFlags=slave
+ KillMode=mixed
+ WatchdogSec=1min

meta/recipes-core/systemd/systemd_229.bb

@@ -54,6 +54,7 @@ SRC_URI = "git://github.com/systemd/systemd.git;protocol=git \
            file://0021-include-missing.h-for-getting-secure_getenv-definiti.patch \
            file://0022-socket-util-don-t-fail-if-libc-doesn-t-support-IDN.patch \
            file://0023-build-sys-fix-build-with-libgrcypt-disabled.patch \
+           file://udev-re-enable-mount-propagation-for-udevd.patch \
 "
 SRC_URI_append_libc-uclibc = "\
            file://0002-units-Prefer-getty-to-agetty-in-console-setup-system.patch \