Re: [PATCH v11 01/17] libxl: fix stubdom console destruction

[Ian Campbell <Ian.Campbell@citrix.com>]

On Mon, 2012-07-23 at 18:27 +0100, Roger Pau Monne wrote:
> Stubdoms have several consoles attached, and they don't follow the
> xenstore protocol for devices, since they are always in state 1. We
> have to add an exception to libxl__initiate_device_remove, so libxl
> doesn't wait for them to reach state 6 (Closed).
> 
> Report: http://markmail.org/message/yqgppcsdip6tnmh6
> 
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Reported-by: Ian Campbell <ian.campbell@eu.citrix.com>
> Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
> ---
>  tools/libxl/libxl_device.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
> index a94beab..c4392fa 100644
> --- a/tools/libxl/libxl_device.c
> +++ b/tools/libxl/libxl_device.c
> @@ -592,8 +592,10 @@ void libxl__initiate_device_remove(libxl__egc *egc,
>          LOG(ERROR, "unable to get info for domain %d", domid);
>          goto out;
>      }
> -    if (QEMU_BACKEND(aodev->dev) &&
> -        (info.paused || info.dying || info.shutdown)) {
> +    if ((QEMU_BACKEND(aodev->dev) &&
> +        (info.paused || info.dying || info.shutdown)) ||
> +        (libxl_is_stubdom(CTX, aodev->dev->domid, NULL) &&
> +        (aodev->dev->backend_kind == LIBXL__DEVICE_KIND_CONSOLE))) {

Is this actually specific to stubdom consoles or is that just where
we've noticed it? I don't see why it wouldn't be relevant to any PV
console other than the first (which I assume you special case
elsewhere?)

Probably the logic would be clearer in a helper, i.e.
dev_is_stubdom_console? or encapsulate both bits of logic in
dev_needs_shutdown?

Does it apply to LIBXL__CONSOLE_BACKEND_IOEMU as well
as ..._XENCONSOLED? I took a look through tools/console and I cannot
find any handling of a state node in xenstore at all, so the XENCONSOLED
case seems clear. I notice that xen_console.c registers the device with
DEVOPS_FLAG_IGNORE_STATE but that only seems to affect startup not
teardown. I don't see a qemu_chr_close (or anything similar) anywhere in
hw/xen_console.c


>          /*
>           * TODO: 4.2 Bodge due to QEMU, see comment on top of
>           * libxl__initiate_device_remove in libxl_internal.h

I suppose this comment needs updating now that the conditional has
changed? In particular the special handling of consoles is not a qemu
related bodge.

Ian.