[arch-projects] [PATCH 4/7] udev: exit on shutdown

Dan McGee dpmcgee at gmail.com
Wed Oct 26 20:12:13 EDT 2011

On Wed, Oct 26, 2011 at 6:38 PM, Tom Gundersen <teg at jklm.no> wrote:
> udev was receiving some events (due to e.g. swapoff) on shutdown
> that caused it to fork new processes. These then receivde TERM before
> they could finish, and complained on the console.
> In principle, I'm worried that, with the right ammonut of bad luck,
> we could fork off some process at exactly the wrong time which escapes
> the killall logic.
> This, by the way, highlights the frailty of the killall stuff.
Two quick thoughts here
1. Is there a need to even call swapoff? I can't believe it is
essential for swap partitions. It unfortunately does makes sense for
swap files so we can later unmount the file system they live on, but
it looks like there is no way to differentiate. Dave, I know you want
to submit a patch to util-linux for this... :)
2. Why do we do anything except unmounting filesystems after the
kill_all call? It seems like we could move the random seed, and
timezone set above it, and then kill udev, and then we'd be safe from
any and all spawned processes.
The only things following would be (hooks excluded) a umount call,
vgchange/cryptsetup calls, a mount call, and either poweroff/reboot.
That seems pretty easy to audit, and I feel like you took a potshot at
the killall thing when in fact udevd was the only bad boy in the
corner causing trouble.

> Signed-off-by: Tom Gundersen <teg at jklm.no>
> ---
>  rc.shutdown |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> diff --git a/rc.shutdown b/rc.shutdown
> index 8363737..5928b2d 100755
> --- a/rc.shutdown
> +++ b/rc.shutdown
> @@ -19,6 +19,8 @@ run_hook shutdown_start
>  stop_all_daemons
> +status "Shutting down UDev" udevadm control --exit
> +
>  status "Deactivating Swap" swapoff -a
>  # stop monitoring of lvm2 groups before unmounting filesystems
> --

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