Re: [PATCH V5 1/3] net/filter: Optimize transfer protocol for filter-mirror/redirector

[Jason Wang <jasowang@redhat.com>]

在 2021/10/28 下午5:05, Zhang Chen 写道:
> Make the vnet header a necessary part of filter transfer protocol.
> It make other modules(like another filter-redirector,colo-compare...)
> know how to parse net packet correctly. If local device is not the
> virtio-net-pci, vnet_hdr_len will be 0.
>
> Signed-off-by: Zhang Chen <chen.zhang@intel.com>
> ---
>   net/filter-mirror.c | 34 ++++++++++++++++------------------
>   1 file changed, 16 insertions(+), 18 deletions(-)
>
> diff --git a/net/filter-mirror.c b/net/filter-mirror.c
> index f20240cc9f..24d3e498e9 100644
> --- a/net/filter-mirror.c
> +++ b/net/filter-mirror.c
> @@ -39,6 +39,7 @@ struct MirrorState {
>       CharBackend chr_in;
>       CharBackend chr_out;
>       SocketReadState rs;
> +    /* Keep compatibility for the management layer */
>       bool vnet_hdr;
>   };
>   
> @@ -48,7 +49,7 @@ static int filter_send(MirrorState *s,
>   {
>       NetFilterState *nf = NETFILTER(s);
>       int ret = 0;
> -    ssize_t size = 0;
> +    ssize_t size = 0, vnet_hdr_len = 0;
>       uint32_t len = 0;
>       char *buf;
>   
> @@ -63,21 +64,18 @@ static int filter_send(MirrorState *s,
>           goto err;
>       }
>   
> -    if (s->vnet_hdr) {
> -        /*
> -         * If vnet_hdr = on, we send vnet header len to make other
> -         * module(like colo-compare) know how to parse net
> -         * packet correctly.
> -         */
> -        ssize_t vnet_hdr_len;
> -
> -        vnet_hdr_len = nf->netdev->vnet_hdr_len;
> +    /*
> +     * The vnet header is the necessary part of filter transfer protocol.
> +     * It make other module(like colo-compare) know how to parse net
> +     * packet correctly. If device is not the virtio-net-pci,
> +     * vnet_hdr_len will be 0.
> +     */
> +    vnet_hdr_len = nf->netdev->vnet_hdr_len;
>   
> -        len = htonl(vnet_hdr_len);
> -        ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)&len, sizeof(len));
> -        if (ret != sizeof(len)) {
> -            goto err;
> -        }
> +    len = htonl(vnet_hdr_len);
> +    ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)&len, sizeof(len));


I wonder if we need to introduce new parameter, e.g force_vnet_hdr here, 
then we can always send vnet_hdr when it is enabled.

Otherwise the "vnet_hdr_support" seems meaningless.

Thanks


> +    if (ret != sizeof(len)) {
> +        goto err;
>       }
>   
>       buf = g_malloc(size);
> @@ -252,7 +250,7 @@ static void filter_redirector_setup(NetFilterState *nf, Error **errp)
>           }
>       }
>   
> -    net_socket_rs_init(&s->rs, redirector_rs_finalize, s->vnet_hdr);
> +    net_socket_rs_init(&s->rs, redirector_rs_finalize, true);
>   
>       if (s->indev) {
>           chr = qemu_chr_find(s->indev);
> @@ -406,14 +404,14 @@ static void filter_mirror_init(Object *obj)
>   {
>       MirrorState *s = FILTER_MIRROR(obj);
>   
> -    s->vnet_hdr = false;
> +    s->vnet_hdr = true;
>   }
>   
>   static void filter_redirector_init(Object *obj)
>   {
>       MirrorState *s = FILTER_REDIRECTOR(obj);
>   
> -    s->vnet_hdr = false;
> +    s->vnet_hdr = true;
>   }
>   
>   static void filter_mirror_fini(Object *obj)