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

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

On Tue, Jan 29, 2013 at 04:55:25PM -0600, Anthony Liguori wrote:
> "Michael S. Tsirkin" <mst@redhat.com> writes:
> 
> > 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.
> 
> Why?  I'd prefer that we didn't rush things into 1.4 just because.
> There's still ample time to respin a corrected series.
> 
> Regards,
> 
> Anthony Liguori

Confused.  Do you want the coding style rework of net/tap.c
switching it from assert(0)/bitfields to abort()/bool for 1.4?

> >
> >
> >> >
> >> > 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
> >> >>>
> >> >>>
> >> >
> > --
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