Re: [PATCH] libxl: Don't segfault on soft-reset failure

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Mar 30, 2022 at 02:17:27PM -0400, Jason Andryuk wrote:
> diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
> index 15ed021f41..631caa416d 100644
> --- a/tools/libs/light/libxl_create.c
> +++ b/tools/libs/light/libxl_create.c
> @@ -1970,7 +1970,8 @@ static void domcreate_complete(libxl__egc *egc,
>      libxl_domain_config *const d_config = dcs->guest_config;
>      libxl_domain_config *d_config_saved = &dcs->guest_config_saved;
>  
> -    libxl__xswait_stop(gc, &dcs->console_xswait);
> +    if (dcs->console_xswait.path)
> +        libxl__xswait_stop(gc, &dcs->console_xswait);

libxl__xswait_stop() needs to be called here. It's a function that can
be called several time without ill effect, as long as `console_xswait`
is initialised properly (by calling libxl__xswait_init() like you did
below.

>      libxl__domain_build_state_dispose(&dcs->build_state);
>  
> @@ -2176,6 +2177,10 @@ static int do_domain_soft_reset(libxl_ctx *ctx,
>                                aop_console_how);
>      cdcs->domid_out = &domid_out;
>  
> +    /* Initialize in case we end up in domcreate_complete without calling
> +     * initiate_domain_create. */

That comment isn't needed. This is just part of the initialisation of
`cdcs->dcs`.

> +    libxl__xswait_init(&cdcs->dcs.console_xswait);
> +
>      dom_path = libxl__xs_get_dompath(gc, domid);
>      if (!dom_path) {
>          LOGD(ERROR, domid, "failed to read domain path");


As part of the patch, could you also move the libxl__xswait_init() call
in initiate_domain_create() to do_domain_create()? That would avoid
`console_xswait` been initialised twice, and do_domain_create() is the
function that initialise `dcs` before calling initiate_domain_create().

Thanks,

-- 
Anthony PERARD