Re: [Xen-devel] [PATCH 4 of 5] tools/libxl: Control network buffering in remus callbacks

[Shriram Rajagopalan <rshriram@xxxxxxxxx>]

On Mon, Aug 26, 2013 at 6:28 PM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:

On 26/08/2013 00:45, rshriram@xxxxxxxxx wrote:
> # HG changeset patch
> # User Shriram Rajagopalan <rshriram@xxxxxxxxx>
> # Date 1377473611 25200
> # Node ID c6804ccfe660cb9c373c5f53a8996d0443316684
> # Parent  4b23104828c09218aa7f9fbde1578bb6706e13d6
> tools/libxl: Control network buffering in remus callbacks
>
> This patch constitutes the core network buffering logic.
> and does the following:
>  a) create a new network buffer when the domain is suspended
>     (remus_domain_suspend_callback)
>  b) release the previous network buffer pertaining to the
>     committed checkpoint (remus_domain_checkpoint_dm_saved)
>
> Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
>
> diff -r 4b23104828c0 -r c6804ccfe660 tools/libxl/libxl_dom.c
> --- a/tools/libxl/libxl_dom.c Sun Aug 25 16:33:29 2013 -0700
> +++ b/tools/libxl/libxl_dom.c Sun Aug 25 16:33:31 2013 -0700
> @@ -1213,12 +1213,28 @@ int libxl__toolstack_save(uint32_t domid
>
>  /*----- remus callbacks -----*/
>
> +/* REMUS TODO: Issue disk checkpoint reqs. */

Why does this comment need to move?

>  static int libxl__remus_domain_suspend_callback(void *data)
>  {
> -    /* REMUS TODO: Issue disk and network checkpoint reqs. */
> -    return libxl__domain_suspend_common_callback(data);
> +    libxl__save_helper_state *shs = data;
> +    libxl__domain_suspend_state *dss = CONTAINER_OF(shs, *dss, shs);
> +    libxl__remus_ctx *remus_ctx = dss->remus_ctx;
> +    int is_suspended = 0;
> +    STATE_AO_GC(dss->ao);
> +
> +    is_suspended = libxl__domain_suspend_common_callback(data);
> +    if (!remus_ctx->netbuf_ctx)

split to new line please.

> return is_suspended;
> +
> +    if (is_suspended) {
> +        if (libxl__remus_netbuf_start_new_epoch(gc, dss->domid,
> +                                                remus_ctx))
> +            return !is_suspended;
> +    }
> +
> +    return is_suspended;

is_suspended is logically a boolean, so should be bool_t.  Unhelpfully,
libxl__domain_suspend_common_callback() returns an int, although its
implementation strictly returns 0 on failure and 1 on success.

IMO, It would probably be best to have "bool_t is_suspended" set to
"!!libxl__domain_suspend_common_callback()", at which the subsequent
return !is_suspended doesn't look as suspect, although that is just a
matter of style.

Did you mean bool (not bool_t) ? Because I didnt see a typedef in libxl folder.

 

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