Re: [Xen-devel] [PATCH v6 09/18] tools/libxl: introduce libxl__domain_common_switch_qemu_logdirty()

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Dec 30, 2015 at 10:28:59AM +0800, Wen Congyang wrote:
> Secondary vm is running in colo mode, we need to send
> secondary vm's dirty page information to master at checkpoint,

In previous patch you called it primary, so perhaps:
s/master/primary/ ?

> so we have to enable qemu logdirty on secondary.
> 
> libxl__domain_suspend_common_switch_qemu_logdirty() is to enable
> qemu logdirty. But it uses domain_save_state, and calls

s/domain_save_state/libxl__domain_save_state/
> libxl__xc_domain_saverestore_async_callback_done()
> before exits. This can not be used for secondary vm.
> 
> Update libxl__domain_suspend_common_switch_qemu_logdirty() to
> introduce a new API libxl__domain_common_switch_qemu_logdirty().
> This API only uses libxl__logdirty_switch, and calls
> lds->callback before exits.

One question - that perhaps had been part of the review earlier
(if so it may be good to include this in the description
so I don't ask silly questions):

Why add this extra API? You could squash 
libxl__domain_suspend_common_switch_qemu_logdirty
and libxl__domain_common_switch_qemu_logdirty code together
and call it libxl_domain_common_and_suspend_common_switch_qemu_logdirty
(ok, just kidding on the name). But - why not have one function
instead of splitting the functionality in two?

Is there another patch that depends on it? If so it may be good
to spell it out, like:

Patch blah blah is going to use it.

Thanks!
> 
> Signed-off-by: Yang Hongyang <hongyang.yang@xxxxxxxxxxxx>
> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_dom_save.c | 95 
> ++++++++++++++++++++++++--------------------
>  tools/libxl/libxl_internal.h |  8 ++++
>  2 files changed, 60 insertions(+), 43 deletions(-)
> 
> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c
> index b3ecad7..79e43f1 100644
> --- a/tools/libxl/libxl_dom_save.c
> +++ b/tools/libxl/libxl_dom_save.c
> @@ -42,7 +42,7 @@ static void switch_logdirty_timeout(libxl__egc *egc, 
> libxl__ev_time *ev,
>  static void switch_logdirty_xswatch(libxl__egc *egc, libxl__ev_xswatch*,
>                              const char *watch_path, const char *event_path);
>  static void switch_logdirty_done(libxl__egc *egc,
> -                                 libxl__domain_save_state *dss, int rc);
> +                                 libxl__logdirty_switch *lds, int rc);
>  
>  static void logdirty_init(libxl__logdirty_switch *lds)
>  {
> @@ -52,13 +52,10 @@ static void logdirty_init(libxl__logdirty_switch *lds)
>  }
>  
>  static void domain_suspend_switch_qemu_xen_traditional_logdirty
> -                               (int domid, unsigned enable,
> -                                libxl__save_helper_state *shs)
> +                               (libxl__egc *egc, int domid, unsigned enable,
> +                                libxl__logdirty_switch *lds)
>  {
> -    libxl__egc *egc = shs->egc;
> -    libxl__domain_save_state *dss = shs->caller_state;
> -    libxl__logdirty_switch *lds = &dss->logdirty;
> -    STATE_AO_GC(dss->ao);
> +    STATE_AO_GC(lds->ao);
>      int rc;
>      xs_transaction_t t = 0;
>      const char *got;
> @@ -120,26 +117,34 @@ static void 
> domain_suspend_switch_qemu_xen_traditional_logdirty
>   out:
>      LOG(ERROR,"logdirty switch failed (rc=%d), abandoning suspend",rc);
>      libxl__xs_transaction_abort(gc, &t);
> -    switch_logdirty_done(egc,dss,rc);
> +    switch_logdirty_done(egc,lds,rc);
>  }
>  
>  static void domain_suspend_switch_qemu_xen_logdirty
> -                               (int domid, unsigned enable,
> -                                libxl__save_helper_state *shs)
> +                               (libxl__egc *egc, int domid, unsigned enable,
> +                                libxl__logdirty_switch *lds)
>  {
> -    libxl__egc *egc = shs->egc;
> -    libxl__domain_save_state *dss = shs->caller_state;
> -    STATE_AO_GC(dss->ao);
> +    STATE_AO_GC(lds->ao);
>      int rc;
>  
>      rc = libxl__qmp_set_global_dirty_log(gc, domid, enable);
> -    if (!rc) {
> -        libxl__xc_domain_saverestore_async_callback_done(egc, shs, 0);
> -    } else {
> +    if (rc)
>          LOG(ERROR,"logdirty switch failed (rc=%d), abandoning suspend",rc);
> +
> +    lds->callback(egc, lds, rc);
> +}
> +
> +static void domain_suspend_switch_qemu_logdirty_done
> +                        (libxl__egc *egc, libxl__logdirty_switch *lds, int 
> rc)
> +{
> +    libxl__domain_save_state *dss = CONTAINER_OF(lds, *dss, logdirty);
> +
> +    if (rc) {
>          dss->rc = rc;
> -        libxl__xc_domain_saverestore_async_callback_done(egc, shs, -1);
> -    }
> +        libxl__xc_domain_saverestore_async_callback_done(egc,
> +                                                         &dss->sws.shs, -1);
> +    } else
> +        libxl__xc_domain_saverestore_async_callback_done(egc, &dss->sws.shs, 
> 0);
>  }
>  
>  void libxl__domain_suspend_common_switch_qemu_logdirty
> @@ -148,42 +153,52 @@ void libxl__domain_suspend_common_switch_qemu_logdirty
>      libxl__save_helper_state *shs = user;
>      libxl__egc *egc = shs->egc;
>      libxl__domain_save_state *dss = shs->caller_state;
> -    STATE_AO_GC(dss->ao);
> +
> +    /* convenience aliases */

/* Convenience aliases. */

> +    libxl__logdirty_switch *const lds = &dss->logdirty;
> +
> +    lds->callback = domain_suspend_switch_qemu_logdirty_done;
> +    libxl__domain_common_switch_qemu_logdirty(egc, domid, enable, lds);
> +}
> +
> +void libxl__domain_common_switch_qemu_logdirty(libxl__egc *egc,
> +                                               int domid, unsigned enable,
> +                                               libxl__logdirty_switch *lds)
> +{
> +    STATE_AO_GC(lds->ao);
>  
>      switch (libxl__device_model_version_running(gc, domid)) {
>      case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
> -        domain_suspend_switch_qemu_xen_traditional_logdirty(domid, enable, 
> shs);
> +        domain_suspend_switch_qemu_xen_traditional_logdirty(egc, domid, 
> enable,
> +                                                            lds);
>          break;
>      case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
> -        domain_suspend_switch_qemu_xen_logdirty(domid, enable, shs);
> +        domain_suspend_switch_qemu_xen_logdirty(egc, domid, enable, lds);
>          break;
>      case LIBXL_DEVICE_MODEL_VERSION_NONE:
> -        libxl__xc_domain_saverestore_async_callback_done(egc, shs, 0);
> +        lds->callback(egc, lds, 0);
>          break;
>      default:
>          LOG(ERROR,"logdirty switch failed"
>              ", no valid device model version found, abandoning suspend");
> -        dss->rc = ERROR_FAIL;
> -        libxl__xc_domain_saverestore_async_callback_done(egc, shs, -1);
> +        lds->callback(egc, lds, ERROR_FAIL);
>      }
>  }
>  static void switch_logdirty_timeout(libxl__egc *egc, libxl__ev_time *ev,
>                                      const struct timeval *requested_abs,
>                                      int rc)
>  {
> -    libxl__domain_save_state *dss = CONTAINER_OF(ev, *dss, logdirty.timeout);
> -    STATE_AO_GC(dss->ao);
> +    libxl__logdirty_switch *lds = CONTAINER_OF(ev, *lds, timeout);
> +    STATE_AO_GC(lds->ao);
>      LOG(ERROR,"logdirty switch: wait for device model timed out");
> -    switch_logdirty_done(egc,dss,ERROR_FAIL);
> +    switch_logdirty_done(egc,lds,ERROR_FAIL);
>  }
>  
>  static void switch_logdirty_xswatch(libxl__egc *egc, libxl__ev_xswatch 
> *watch,
>                              const char *watch_path, const char *event_path)
>  {
> -    libxl__domain_save_state *dss =
> -        CONTAINER_OF(watch, *dss, logdirty.watch);
> -    libxl__logdirty_switch *lds = &dss->logdirty;
> -    STATE_AO_GC(dss->ao);
> +    libxl__logdirty_switch *lds = CONTAINER_OF(watch, *lds, watch);
> +    STATE_AO_GC(lds->ao);
>      const char *got;
>      xs_transaction_t t = 0;
>      int rc;
> @@ -229,28 +244,20 @@ static void switch_logdirty_xswatch(libxl__egc *egc, 
> libxl__ev_xswatch *watch,
>      if (rc <= 0) {
>          if (rc < 0)
>              LOG(ERROR,"logdirty switch: failed (rc=%d)",rc);
> -        switch_logdirty_done(egc,dss,rc);
> +        switch_logdirty_done(egc,lds,rc);
>      }
>  }
>  
>  static void switch_logdirty_done(libxl__egc *egc,
> -                                 libxl__domain_save_state *dss,
> +                                 libxl__logdirty_switch *lds,
>                                   int rc)
>  {
> -    STATE_AO_GC(dss->ao);
> -    libxl__logdirty_switch *lds = &dss->logdirty;
> +    STATE_AO_GC(lds->ao);
>  
>      libxl__ev_xswatch_deregister(gc, &lds->watch);
>      libxl__ev_time_deregister(gc, &lds->timeout);
>  
> -    int broke;
> -    if (rc) {
> -        broke = -1;
> -        dss->rc = rc;
> -    } else {
> -        broke = 0;
> -    }
> -    libxl__xc_domain_saverestore_async_callback_done(egc, &dss->sws.shs, 
> broke);
> +    lds->callback(egc, lds, rc);
>  }
>  
>  /*----- callbacks, called by xc_domain_save -----*/
> @@ -346,6 +353,8 @@ void libxl__domain_save(libxl__egc *egc, 
> libxl__domain_save_state *dss)
>  
>      dss->rc = 0;
>      logdirty_init(&dss->logdirty);
> +    dss->logdirty.ao = ao;
> +
>      dsps->ao = ao;
>      dsps->domid = domid;
>      rc = libxl__domain_suspend_init(egc, dsps);
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index 4872619..552692f 100644
> --- a/tools/libxl/libxl_internal.h
> +++ b/tools/libxl/libxl_internal.h
> @@ -3071,6 +3071,11 @@ libxl__stream_write_inuse(const 
> libxl__stream_write_state *stream)
>  }
>  
>  typedef struct libxl__logdirty_switch {
> +    /* set by caller of libxl__domain_common_switch_qemu_logdirty */

s/set/Set/

> +    libxl__ao *ao;
> +    void (*callback)(libxl__egc *egc, struct libxl__logdirty_switch *lds,
> +                     int rc);
> +
>      const char *cmd;
>      const char *cmd_path;
>      const char *ret_path;
> @@ -3490,6 +3495,9 @@ void 
> libxl__xc_domain_saverestore_async_callback_done(libxl__egc *egc,
>  
>  _hidden void libxl__domain_suspend_common_switch_qemu_logdirty
>                                 (int domid, unsigned int enable, void *data);
> +_hidden void libxl__domain_common_switch_qemu_logdirty(libxl__egc *egc,
> +                                               int domid, unsigned enable,
> +                                               libxl__logdirty_switch *lds);
>  _hidden int libxl__save_emulator_xenstore_data(libxl__domain_save_state *dss,
>                                                 char **buf, uint32_t *len);
>  _hidden int libxl__restore_emulator_xenstore_data
> -- 
> 2.5.0
> 
> 
> 
> 
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