Re: [Xen-devel] [PATCH v2 COLOPre 10/13] tools/libxl: Add back channel to allow migration target send data back

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jun 08, 2015 at 11:43:14AM +0800, Yang Hongyang wrote:
> From: Wen Congyang <wency@xxxxxxxxxxxxxx>
> 
> In colo mode, slave needs to send data to master, but the io_fd
> only can be written in master, and only can be read in slave.
> Save recv_fd in domain_suspend_state, and send_fd in
> domain_create_state.
> 

You failed to mention in commit message new structures are introduced in
IDL.

> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
> ---
>  tools/libxl/libxl.c          |  2 +-
>  tools/libxl/libxl_create.c   | 14 ++++++++++----
>  tools/libxl/libxl_internal.h |  2 ++
>  tools/libxl/libxl_types.idl  |  7 +++++++
>  tools/libxl/xl_cmdimpl.c     |  7 +++++++

You also need to add LIBXL_HAVE in libxl.h.

>  5 files changed, 27 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 5c843c2..36b97fe 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -832,7 +832,7 @@ int libxl_domain_remus_start(libxl_ctx *ctx, 
> libxl_domain_remus_info *info,
>      dss->callback = remus_failover_cb;
>      dss->domid = domid;
>      dss->fd = send_fd;
> -    /* TODO do something with recv_fd */
> +    dss->recv_fd = recv_fd;
>      dss->type = type;
>      dss->live = 1;
>      dss->debug = 0;
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index 86384d2..bd8149c 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -1577,8 +1577,8 @@ static void domain_create_cb(libxl__egc *egc,
>                               int rc, uint32_t domid);
>  
>  static int do_domain_create(libxl_ctx *ctx, libxl_domain_config *d_config,
> -                            uint32_t *domid,
> -                            int restore_fd, int checkpointed_stream,
> +                            uint32_t *domid, int restore_fd,
> +                            int send_fd, int checkpointed_stream,
>                              const libxl_asyncop_how *ao_how,
>                              const libxl_asyncprogress_how *aop_console_how)
>  {
> @@ -1591,6 +1591,7 @@ static int do_domain_create(libxl_ctx *ctx, 
> libxl_domain_config *d_config,
>      libxl_domain_config_init(&cdcs->dcs.guest_config_saved);
>      libxl_domain_config_copy(ctx, &cdcs->dcs.guest_config_saved, d_config);
>      cdcs->dcs.restore_fd = restore_fd;
> +    cdcs->dcs.send_fd = send_fd;
>      cdcs->dcs.callback = domain_create_cb;
>      cdcs->dcs.checkpointed_stream = checkpointed_stream;
>      libxl__ao_progress_gethow(&cdcs->dcs.aop_console_how, aop_console_how);
> @@ -1619,7 +1620,7 @@ int libxl_domain_create_new(libxl_ctx *ctx, 
> libxl_domain_config *d_config,
>                              const libxl_asyncop_how *ao_how,
>                              const libxl_asyncprogress_how *aop_console_how)
>  {
> -    return do_domain_create(ctx, d_config, domid, -1, 0,
> +    return do_domain_create(ctx, d_config, domid, -1, -1, 0,
>                              ao_how, aop_console_how);
>  }
>  
> @@ -1629,7 +1630,12 @@ int libxl_domain_create_restore(libxl_ctx *ctx, 
> libxl_domain_config *d_config,
>                                  const libxl_asyncop_how *ao_how,
>                                  const libxl_asyncprogress_how 
> *aop_console_how)
>  {
> -    return do_domain_create(ctx, d_config, domid, restore_fd,
> +    int send_fd = -1;
> +
> +    if (params->checkpointed_stream == LIBXL_CHECKPOINTED_STREAM_COLO)
> +        send_fd = params->send_fd;
> +
> +    return do_domain_create(ctx, d_config, domid, restore_fd, send_fd,
>                              params->checkpointed_stream, ao_how, 
> aop_console_how);
>  }
>  
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index fbbae93..6d214b5 100644
> --- a/tools/libxl/libxl_internal.h
> +++ b/tools/libxl/libxl_internal.h
> @@ -2874,6 +2874,7 @@ struct libxl__domain_save_state {
>  
>      uint32_t domid;
>      int fd;
> +    int recv_fd;
>      libxl_domain_type type;
>      int live;
>      int debug;
> @@ -3143,6 +3144,7 @@ struct libxl__domain_create_state {
>      libxl_domain_config *guest_config;
>      libxl_domain_config guest_config_saved; /* vanilla config */
>      int restore_fd;
> +    int send_fd;
>      libxl__domain_create_cb *callback;
>      libxl_asyncprogress_how aop_console_how;
>      /* private to domain_create */
> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> index 23f27d4..8a3d7ba 100644
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -198,6 +198,12 @@ libxl_viridian_enlightenment = 
> Enumeration("viridian_enlightenment", [
>      (3, "reference_tsc"),
>      ])
>  
> +libxl_checkpointed_stream = Enumeration("checkpointed_stream", [
> +    (0, "NONE"),
> +    (1, "REMUS"),
> +    (2, "COLO"),
> +    ], init_val = 0)

The default init_val is 0 so you don't need to write it down.

> +
>  #
>  # Complex libxl types
>  #
> @@ -346,6 +352,7 @@ libxl_domain_create_info = Struct("domain_create_info",[
>  
>  libxl_domain_restore_params = Struct("domain_restore_params", [
>      ("checkpointed_stream", integer),
> +    ("send_fd", integer),

I'm not entirely sure if we want to bury an extra argument here.

After looking at code I think you're trying to work around API
limitation. I think we are safe to extend the API -- we've already done
that before. See libxl.h around line 990.

Ian and Ian, what do you think?

>      ])
>  
>  libxl_domain_sched_params = Struct("domain_sched_params",[
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index c858068..adfadd1 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c

I would also suggest you rename the last argument of migrate_receive in
this file from "remus" to "checkpointed_stream_type" since the semantics
of that parameter has changed.

Wei.

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