Re: [PATCH 4/5] libxl: wait for stubdom to be ready

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

On Fri, 2015-03-13 at 10:34 +0000, Wei Liu wrote:
> Watch /local/domain/$dm_domid/device-model/$domid/state, wait until
> state turns "running" then unpause guest.
> 
> LIBXL_STUBDOM_START_TIMEOUT is the timeout used wait for stubdom to be
> ready. My test on a very old machine (Core 2 6400) showed that it might
> need more than 20s before the stubdom is ready to serve DomU.
> 
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> ---
>  tools/libxl/libxl_dm.c       | 39 ++++++++++++++++++++++++++++++++++++++-
>  tools/libxl/libxl_internal.h |  2 ++
>  2 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index 4a38455..ad2ef41 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -984,6 +984,8 @@ static void stubdom_pvqemu_cb(libxl__egc *egc,
>  static void spawn_stubdom_pvqemu_destroy_cb(libxl__egc *egc,
>                                              libxl__destroy_domid_state *dis,
>                                              int rc);
> +static void stubdom_xswait_cb(libxl__egc *egc, libxl__xswait_state *xswait,
> +                              int rc, const char *p);
>  
>  char *libxl__stub_dm_name(libxl__gc *gc, const char *guest_name)
>  {
> @@ -1273,16 +1275,51 @@ static void stubdom_pvqemu_cb(libxl__egc *egc,
>      rc = libxl_domain_unpause(CTX, dm_domid);
>      if (rc) goto out;
>  
> +    libxl__xswait_init(&sdss->xswait);
> +    sdss->xswait.ao = ao;
> +    sdss->xswait.what = GCSPRINTF("Stubdom %d startup", dm_domid);

Maybe include the domid too, e.g. "Stubdom %d for dom %d startup"?

(And probably %u throughout?)

> +static void stubdom_xswait_cb(libxl__egc *egc, libxl__xswait_state *xswait,
> +                              int rc, const char *p)
> +{
> +    EGC_GC;
> +    libxl__stub_dm_spawn_state *sdss = CONTAINER_OF(xswait, *sdss, xswait);
> +    uint32_t dm_domid = sdss->pvqemu.guest_domid;
> +
> +    if (rc) {
> +        if (rc == ERROR_TIMEDOUT)
> +            LOG(ERROR, "%s: startup timed out", xswait->what);
> +        goto out;
> +    }
> +
> +    if (!p) return;
> +
> +    if (strcmp(p, "running"))
> +        return;
>   out:
>      if (rc) {
>          if (dm_domid) {
> -            sdss->dis.ao = ao;
> +            sdss->dis.ao = sdss->dm.spawn.ao;
>              sdss->dis.domid = dm_domid;
>              sdss->dis.callback = spawn_stubdom_pvqemu_destroy_cb;
>              libxl__destroy_domid(egc, &sdss->dis);
> +            libxl__xswait_stop(gc, xswait);

Can you do this once befire the if (rc)?

Ian.