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

[Blue Swirl]

On Tue, Jan 29, 2013 at 1:50 PM, Jason Wang <address@hidden> wrote:
> On 01/26/2013 03:13 AM, Blue Swirl wrote:
>> 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()
>
> 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
>>>
>>>
>