[arch-projects] [RFC] [PATCH] [mkinitcpio] Cleanly stop udev >= 168 as recommended by upstream.

[Dave Reisner]

On Mon, May 02, 2011 at 03:16:56AM -0300, Gerardo Exequiel Pozzi wrote:
> On 05/02/2011 01:22 AM, Dave Reisner wrote:
> >On Mon, May 02, 2011 at 12:40:14AM -0300, Gerardo Exequiel Pozzi wrote:
> >>On 05/02/2011 12:39 AM, Gerardo Exequiel Pozzi wrote:
> >>>N0: udev>= 168 is needed.
> >>>N1: I guess the order is correct (first cleanup then exit).
> >>>N2: device-mapper/LVM udev rules must be parsed for initramfs creation
> >>>     to add OPTIONS+="db_persist"
> >>>
> >>>> From udev NEWS:
> >>>The running udev daemon can now cleanly shut down with:
> >>>   udevadm control --exit
> >>>
> >>>Udev in initramfs should clean the state of the udev database
> >>>with: udevadm info --cleanup-db which will remove all state left
> >>>behind from events/rules in initramfs. If initramfs uses
> >>>--cleanup-db and device-mapper/LVM, the rules in initramfs need
> >>>to add OPTIONS+="db_persist" for all dm devices. This will
> >>>prevent removal of the udev database for these devices.
> >>>
> >>>Signed-off-by: Gerardo Exequiel Pozzi<vmlinuz386 at yahoo.com.ar>
> >>>---
> >>>  init |   12 ++++--------
> >>>  1 files changed, 4 insertions(+), 8 deletions(-)
> >>>
> >>>diff --git a/init b/init
> >>>index 7b81a1a..f586220 100644
> >>>--- a/init
> >>>+++ b/init
> >>>@@ -118,15 +118,11 @@ elif [ ! -x "/new_root${init}" ]; then
> >>>      launch_interactive_shell --exec
> >>>  fi
> >>>
> >>>-#Special handling if udev is running
> >>>-udevpid=$(/bin/pidof udevd)
> >>>-if [ -n "${udevpid}" ]; then
> >>>-    # Settle pending uevents, then kill udev
> >>>+# Stop udevd if is running
> >>>+if [ "${udevd_running}" -eq 1 ]; then
> >>>      /sbin/udevadm settle
> >>>-    /bin/kill ${udevpid}>   /dev/null 2>&1
> >>>-    while /bin/pidof udevd>/dev/null; do
> >>>-        sleep 0.1
> >>>-    done
> >>>+    /sbin/udevadm info --cleanup-db
> >>>+    /sbin/udevadm control --exit
> >>>  fi
> >>>
> >>>  for d in proc sys dev run; do
> >>This just keep settle command.
> >>
> >>-- 
> >>Gerardo Exequiel Pozzi
> >>\cos^2\alpha + \sin^2\alpha = 1
> >>
> >The settle is actually unnecessary here, as its called as part of the
> >udev hook.  I don't see a need to call it twice. On the other hand, I've
> >notice that dracut makes the call 'udevadm control --stop-exec-queue'
> >prior to shutting down udevd. Perhaps we should be using that instead?
> >
> >dave
> >
> sure?
> 
> I think this:
> 
> --------------------
> launch udevd --daemon
> 
> [udev]
> launch triggers
> settle
> [/udev]
> 
> [other hooks]
> other possible uevents
> [/other hooks]
> 
> at this point should wait for all uevents processed (settle) then
> stop udev (control --exit)
> ----------------
> 
> stop-exec-queue just ignore all events (stop process them) and queue
> all incomming events. I think this is what do not want to do.
> 

Not sure I understand the logic here. By the time you're ready to shut
down udev, your root is mounted and $init exists. Queued uevents are
very likely for hardware that we don't currently have modules for. What
other uevents would we be interested in at this point?

dave