Re: [Qemu-devel] [PATCH COLO-Frame v14 35/40] COLO/filter: add each netdev a buffer filter

[Jason Wang <jasowang@redhat.com>]

On 02/06/2016 05:28 PM, zhanghailiang wrote:
> For COLO periodic mode, it need to buffer packets that
> sent by VM, and we will not release these packets until
> finish a checkpoint.
>
> Here, we add each netdev a buffer-filter that will be controlled
> by COLO. It is disabled by default, and the packets will not pass
> through these filters. If users don't enable COLO while configure
> qemu, these buffer-filters will not be added.
>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Yang Hongyang <hongyang.yang@easystack.cn>
> ---
> v14:
> - New patch
> ---
>  include/migration/colo.h |  2 ++
>  include/net/filter.h     |  2 ++
>  migration/colo-comm.c    |  5 +++++
>  migration/colo.c         | 20 ++++++++++++++++++++
>  net/filter-buffer.c      |  2 --
>  stubs/migration-colo.c   |  4 ++++
>  6 files changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/include/migration/colo.h b/include/migration/colo.h
> index 919b135..22b92c9 100644
> --- a/include/migration/colo.h
> +++ b/include/migration/colo.h
> @@ -37,4 +37,6 @@ COLOMode get_colo_mode(void);
>  void colo_do_failover(MigrationState *s);
>  
>  bool colo_shutdown(void);
> +void colo_add_buffer_filter(const char *netdev_id, void *opaque);
> +
>  #endif
> diff --git a/include/net/filter.h b/include/net/filter.h
> index 0159080..0da0d97 100644
> --- a/include/net/filter.h
> +++ b/include/net/filter.h
> @@ -22,6 +22,8 @@
>  #define NETFILTER_CLASS(klass) \
>      OBJECT_CLASS_CHECK(NetFilterClass, (klass), TYPE_NETFILTER)
>  
> +#define TYPE_FILTER_BUFFER "filter-buffer"
> +
>  typedef void (FilterSetup) (NetFilterState *nf, Error **errp);
>  typedef void (FilterCleanup) (NetFilterState *nf);
>  /*
> diff --git a/migration/colo-comm.c b/migration/colo-comm.c
> index 3943e94..91d873e 100644
> --- a/migration/colo-comm.c
> +++ b/migration/colo-comm.c
> @@ -13,6 +13,7 @@
>  
>  #include <migration/colo.h>
>  #include "trace.h"
> +#include <net/net.h>
>  
>  typedef struct {
>       bool colo_requested;
> @@ -58,6 +59,10 @@ static const VMStateDescription colo_state = {
>  void colo_info_init(void)
>  {
>      vmstate_register(NULL, 0, &colo_state, &colo_info);
> +    /* FIXME: Remove this after COLO switch to use colo-proxy */
> +    if (colo_supported()) {
> +        netdev_init_add_handler(colo_add_buffer_filter, NULL);
> +    }
>  }
>  
>  bool migration_incoming_enable_colo(void)
> diff --git a/migration/colo.c b/migration/colo.c
> index 98a12fc..235578b 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -18,6 +18,8 @@
>  #include "qemu/error-report.h"
>  #include "migration/failover.h"
>  #include "qapi-event.h"
> +#include "net/net.h"
> +#include "net/filter.h"
>  
>  static bool vmstate_loading;
>  
> @@ -380,6 +382,24 @@ static int colo_prepare_before_save(MigrationState *s)
>      return ret;
>  }
>  
> +void colo_add_buffer_filter(const char *netdev_id, void *opaque)
> +{
> +    NetFilterState *nf;
> +    char filter_name[128];
> +    Error *errp = NULL;
> +
> +    snprintf(filter_name, sizeof(filter_name),
> +            "%scolo", netdev_id);
> +    nf = netdev_add_filter(netdev_id, TYPE_FILTER_BUFFER, filter_name, false,
> +                           &errp);

Using netdev_add_filter() is too heavyweight and also a overkill. Why
not simply call object_new_with_props() with what ever props you want
(e.g interval=0) here?

> +    if (errp) {
> +        error_report_err(errp);
> +        return;
> +    }
> +    /* Only buffer the packets that sent out by VM */
> +    nf->direction = NET_FILTER_DIRECTION_RX;
> +}
> +
>  static void colo_process_checkpoint(MigrationState *s)
>  {
>      QEMUSizedBuffer *buffer = NULL;
> diff --git a/net/filter-buffer.c b/net/filter-buffer.c
> index 58cea8f..e70d156 100644
> --- a/net/filter-buffer.c
> +++ b/net/filter-buffer.c
> @@ -16,8 +16,6 @@
>  #include "qapi-visit.h"
>  #include "qom/object.h"
>  
> -#define TYPE_FILTER_BUFFER "filter-buffer"
> -
>  #define FILTER_BUFFER(obj) \
>      OBJECT_CHECK(FilterBufferState, (obj), TYPE_FILTER_BUFFER)
>  
> diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
> index 1996cd9..8e74acb 100644
> --- a/stubs/migration-colo.c
> +++ b/stubs/migration-colo.c
> @@ -48,3 +48,7 @@ bool colo_shutdown(void)
>  {
>      return false;
>  }
> +
> +void colo_add_buffer_filter(const char *netdev_id, void *opaque)
> +{
> +}