Re: [Qemu-devel] [PATCH 16/16] hub: add the support for hub own flow control

[Laszlo Ersek <lersek@redhat.com>]

On 07/20/12 14:01, Stefan Hajnoczi wrote:
> From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
> 
> Only when all other hub port's *peer* .can_receive() all return 1,
> the source hub port .can_receive() return 1.
> 
> Reviewed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Probably a typo.

> Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> ---
>  net/hub.c |   27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/net/hub.c b/net/hub.c
> index f697a78..2d67df5 100644
> --- a/net/hub.c
> +++ b/net/hub.c
> @@ -15,6 +15,7 @@
>  #include "monitor.h"
>  #include "net.h"
>  #include "hub.h"
> +#include "iov.h"
>  
>  /*
>   * A hub broadcasts incoming packets to all its ports except the source port.
> @@ -59,16 +60,16 @@ static ssize_t net_hub_receive_iov(NetHub *hub, NetHubPort *source_port,
>                                     const struct iovec *iov, int iovcnt)
>  {
>      NetHubPort *port;
> -    ssize_t ret = 0;
> +    ssize_t len = iov_size(iov, iovcnt);
>  
>      QLIST_FOREACH(port, &hub->ports, next) {
>          if (port == source_port) {
>              continue;
>          }
>  
> -        ret = qemu_sendv_packet(&port->nc, iov, iovcnt);
> +        qemu_sendv_packet(&port->nc, iov, iovcnt);
>      }
> -    return ret;
> +    return len;
>  }

This seems to consolidate net_hub_receive_iov()'s retval with that of
net_hub_receive(), but may I ask why it used to be calculated differently?


>  
>  static NetHub *net_hub_new(unsigned int id)
> @@ -85,6 +86,25 @@ static NetHub *net_hub_new(unsigned int id)
>      return hub;
>  }
>  
> +static int net_hub_port_can_receive(NetClientState *nc)
> +{
> +    NetHubPort *port;
> +    NetHubPort *src_port = DO_UPCAST(NetHubPort, nc, nc);
> +    NetHub *hub = src_port->hub;
> +
> +    QLIST_FOREACH(port, &hub->ports, next) {
> +        if (port == src_port) {
> +            continue;
> +        }
> +
> +        if (!qemu_can_send_packet(&port->nc)) {
> +            return 0;
> +        }
> +    }
> +
> +    return 1;
> +}
> +

(qemu_can_send_packet() handles a NULL sender->peer, OK.)

No further comments for the series.

Thanks!
Laszlo