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

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jan 29, 2013 at 08:10:26PM +0000, Blue Swirl wrote:
> On Tue, Jan 29, 2013 at 1:50 PM, Jason Wang <jasowang@redhat.com> wrote:
> > On 01/26/2013 03:13 AM, Blue Swirl wrote:
> >> On Fri, Jan 25, 2013 at 10:35 AM, Jason Wang <jasowang@redhat.com> 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 <jasowang@redhat.com>
> >>> ---
> >>>  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()
> >
> > This is just to be consistent with the reset of the helpers in this file.
> >>
> >>> +}
> >>> +
> >>> +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?
> >
> > Also to be consistent with other field. If you wish I can send patches
> > to convert all those bit field to bool on top of this series.
> 
> That would be nice, likewise for the assert(0).

OK so let's go ahead with this patchset as is,
and a cleanup patch will be send after 1.4 then.


> >
> > Thanks
> >>>      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
> >>>
> >>>
> >