busybox: mdev: Use mdev.seq

/dev/mdev.seq exists to synchronize concurrently running instances of
mdev and to ensure that they execute in the proper order.  Without this
synchronization, it is possible to have inconsistent mount points, to
leak device nodes, or to have a node erroneously removed in rapid
hotplug scenarios.

Enable the use of mdev.seq by creating an empty /dev/mdev.seq at boot.

Signed-off-by: Richard Tollerton <rich.tollerton@ni.com>
Signed-off-by: Ben Shelton <ben.shelton@ni.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/recipes-core/busybox/files/mdev b/meta/recipes-core/busybox/files/mdev
index f7ed1f3d675991ad55c60163bb4a2fda1ea615a6..c4447ef160246c66127732e80cdc078737ff8833 100755 (executable)
--- a/meta/recipes-core/busybox/files/mdev
+++ b/meta/recipes-core/busybox/files/mdev
@@ -4,5 +4,6 @@ mount -t tmpfs tmpfs /dev  -o size=64k,mode=0755
 mkdir /dev/pts /dev/shm
 chmod 777 /dev/shm
 mount -t devpts devpts /dev/pts
+touch /dev/mdev.seq
 echo "/sbin/mdev" > /proc/sys/kernel/hotplug
 mdev -s