Patchwork [V2,11/20] tap: support enabling or disabling a queue

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Submitter Jason Wang
Date Jan. 25, 2013, 10:35 a.m.
Message ID <1359110143-42984-12-git-send-email-jasowang@redhat.com>
Download mbox | patch
Permalink /patch/215626/
State New
Headers show

Comments

Jason Wang - Jan. 25, 2013, 10:35 a.m.
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(-)
Blue Swirl - Jan. 25, 2013, 7:13 p.m.
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()

> +}
> +
> +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
>
>
Jason Wang - Jan. 29, 2013, 1:50 p.m.
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.

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
>>
>>
Blue Swirl - Jan. 29, 2013, 8:10 p.m.
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).

>
> 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
>>>
>>>
>
Michael S. Tsirkin - Jan. 29, 2013, 10:11 p.m.
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
> >>>
> >>>
> >
Anthony Liguori - Jan. 29, 2013, 10:55 p.m.
"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

>
>
>> >
>> > 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
>> >>>
>> >>>
>> >
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
Michael S. Tsirkin - Jan. 29, 2013, 11:03 p.m.
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
> >> >>>
> >> >>>
> >> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe kvm" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
Jason Wang - Jan. 30, 2013, 9:46 a.m.
On 01/30/2013 07:03 AM, Michael S. Tsirkin wrote:
> 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?

I will send a new series with the patches that addresses Blue's comments
on assert(0) and bitfields.

Thanks
>>>
>>>>> 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
>>>>>>>
>>>>>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

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);
+}
+
+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;
     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;
+    }
+}