Re: [Qemu-devel] [PATCH V2 11/20] tap: support enabling or disabling a queue

[Blue Swirl]

On Fri, Jan 25, 2013 at 10:35 AM, Jason Wang <address@hidden> wrote:
> This patch introduce a new bit - enabled in TAPState which tracks whether a
> specific queue/fd is enabled. The tap/fd is enabled during initialization and
> could be enabled/disabled by tap_enalbe() and tap_disable() which calls 
> platform
> specific helpers to do the real work. Polling of a tap fd can only done when
> the tap was enabled.
>
> Signed-off-by: Jason Wang <address@hidden>
> ---
>  include/net/tap.h |    2 ++
>  net/tap-win32.c   |   10 ++++++++++
>  net/tap.c         |   43 ++++++++++++++++++++++++++++++++++++++++---
>  3 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/tap.h b/include/net/tap.h
> index bb7efb5..0caf8c4 100644
> --- a/include/net/tap.h
> +++ b/include/net/tap.h
> @@ -35,6 +35,8 @@ int tap_has_vnet_hdr_len(NetClientState *nc, int len);
>  void tap_using_vnet_hdr(NetClientState *nc, int using_vnet_hdr);
>  void tap_set_offload(NetClientState *nc, int csum, int tso4, int tso6, int 
> ecn, int ufo);
>  void tap_set_vnet_hdr_len(NetClientState *nc, int len);
> +int tap_enable(NetClientState *nc);
> +int tap_disable(NetClientState *nc);
>
>  int tap_get_fd(NetClientState *nc);
>
> diff --git a/net/tap-win32.c b/net/tap-win32.c
> index 265369c..a2cd94b 100644
> --- a/net/tap-win32.c
> +++ b/net/tap-win32.c
> @@ -764,3 +764,13 @@ void tap_set_vnet_hdr_len(NetClientState *nc, int len)
>  {
>      assert(0);
>  }
> +
> +int tap_enable(NetClientState *nc)
> +{
> +    assert(0);

abort()

> +}
> +
> +int tap_disable(NetClientState *nc)
> +{
> +    assert(0);
> +}
> diff --git a/net/tap.c b/net/tap.c
> index 67080f1..95e557b 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -59,6 +59,7 @@ typedef struct TAPState {
>      unsigned int write_poll : 1;
>      unsigned int using_vnet_hdr : 1;
>      unsigned int has_ufo: 1;
> +    unsigned int enabled : 1;

bool without bit field?

>      VHostNetState *vhost_net;
>      unsigned host_vnet_hdr_len;
>  } TAPState;
> @@ -72,9 +73,9 @@ static void tap_writable(void *opaque);
>  static void tap_update_fd_handler(TAPState *s)
>  {
>      qemu_set_fd_handler2(s->fd,
> -                         s->read_poll  ? tap_can_send : NULL,
> -                         s->read_poll  ? tap_send     : NULL,
> -                         s->write_poll ? tap_writable : NULL,
> +                         s->read_poll && s->enabled ? tap_can_send : NULL,
> +                         s->read_poll && s->enabled ? tap_send     : NULL,
> +                         s->write_poll && s->enabled ? tap_writable : NULL,
>                           s);
>  }
>
> @@ -339,6 +340,7 @@ static TAPState *net_tap_fd_init(NetClientState *peer,
>      s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
>      s->using_vnet_hdr = 0;
>      s->has_ufo = tap_probe_has_ufo(s->fd);
> +    s->enabled = 1;
>      tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
>      /*
>       * Make sure host header length is set correctly in tap:
> @@ -737,3 +739,38 @@ VHostNetState *tap_get_vhost_net(NetClientState *nc)
>      assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
>      return s->vhost_net;
>  }
> +
> +int tap_enable(NetClientState *nc)
> +{
> +    TAPState *s = DO_UPCAST(TAPState, nc, nc);
> +    int ret;
> +
> +    if (s->enabled) {
> +        return 0;
> +    } else {
> +        ret = tap_fd_enable(s->fd);
> +        if (ret == 0) {
> +            s->enabled = 1;
> +            tap_update_fd_handler(s);
> +        }
> +        return ret;
> +    }
> +}
> +
> +int tap_disable(NetClientState *nc)
> +{
> +    TAPState *s = DO_UPCAST(TAPState, nc, nc);
> +    int ret;
> +
> +    if (s->enabled == 0) {
> +        return 0;
> +    } else {
> +        ret = tap_fd_disable(s->fd);
> +        if (ret == 0) {
> +            qemu_purge_queued_packets(nc);
> +            s->enabled = 0;
> +            tap_update_fd_handler(s);
> +        }
> +        return ret;
> +    }
> +}
> --
> 1.7.1
>
>