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

[Anthony Liguori <aliguori@us.ibm.com>]

"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
>> >>>
>> >>>
>> >
> --
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