Re: [Qemu-devel] [PATCH V6 02/10] net/filter-mirror.c: Make filter mirror support vnet support.

[Jason Wang]

On 2017年06月07日 17:55, Zhang Chen wrote:
> We add the vnet_hdr_support option for filter-mirror, default is disable.

s/disable/disabled/

> If you use virtio-net-pci net driver, please enable it.
> You can use it for example:
> -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0,vnet_hdr_support
>
> If have vnet_hdr_support flag,

If it has

>   we will change the send packet format from

s/send/sending/

> struct {int size; const uint8_t buf[];} to {int size; int vnet_hdr_len; const 
> uint8_t buf[];}.
> make other module(like colo-compare) know how to parse net packet correctly.

Please double check the commit logs, some have obvious grammar issues.

> Signed-off-by: Zhang Chen <address@hidden>
> ---
>   net/filter-mirror.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++----
>   qemu-options.hx     |  5 ++--
>   2 files changed, 66 insertions(+), 8 deletions(-)
>
> diff --git a/net/filter-mirror.c b/net/filter-mirror.c
> index 72fa7c2..50aa81b 100644
> --- a/net/filter-mirror.c
> +++ b/net/filter-mirror.c
> @@ -38,15 +38,17 @@ typedef struct MirrorState {
>       NetFilterState parent_obj;
>       char *indev;
>       char *outdev;
> +    bool vnet_hdr;
>       CharBackend chr_in;
>       CharBackend chr_out;
>       SocketReadState rs;
>   } MirrorState;
>   
> -static int filter_mirror_send(CharBackend *chr_out,
> +static int filter_mirror_send(MirrorState *s,
>                                 const struct iovec *iov,
>                                 int iovcnt)

This function were renamed to filter_send in your commit 
e05dc4cf56d70225fc76225a3fd7df9f7b8ca5f9 ("net/filter-mirror.c: Rename 
filter_mirror_send() and fix codestyle")

>   {
> +    NetFilterState *nf = NETFILTER(s);
>       int ret = 0;
>       ssize_t size = 0;
>       uint32_t len = 0;
> @@ -58,14 +60,43 @@ static int filter_mirror_send(CharBackend *chr_out,
>       }
>   
>       len = htonl(size);
> -    ret = qemu_chr_fe_write_all(chr_out, (uint8_t *)&len, sizeof(len));
> +    ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)&len, sizeof(len));

This looks a independent change, please do it in another patch.

>       if (ret != sizeof(len)) {
>           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;
> +
> +        /*
> +         * In anytime, nf->netdev and nf->netdev->peer both have a 
> vnet_hdr_len,
> +         * Here we just find out which is we need. When filter set RX or TX
> +         * that the real vnet_hdr_len are different.
> +         */

Let's remove the comment and let code explain itself.

> +        if (nf->direction == NET_FILTER_DIRECTION_RX ||
> +            nf->direction == NET_FILTER_DIRECTION_ALL) {
> +            vnet_hdr_len = nf->netdev->vnet_hdr_len;

This can only work if e.g virtio-net set its own vnet_hdr_len. But looks 
like it use guest_hdr_len instead.

And using NET_FILTER_DIRECTION_ALL looks suspicious. Maybe we should 
accept sender from its caller and compare it with nf->netdev to get the 
correct direction.

> +        } else if (nf->direction == NET_FILTER_DIRECTION_TX) {
> +            vnet_hdr_len = nf->netdev->peer->vnet_hdr_len;

This looks wrong, TX means the packet were sent from netdev, we should 
care nf->netdev's hdrlen.

> +        } else {
> +            return 0;
> +        }
> +
> +        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;
> +        }
> +    }
> +
>       buf = g_malloc(size);
>       iov_to_buf(iov, iovcnt, 0, buf, size);
> -    ret = qemu_chr_fe_write_all(chr_out, (uint8_t *)buf, size);
> +    ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)buf, size);
>       g_free(buf);
>       if (ret != size) {
>           goto err;
> @@ -141,7 +172,7 @@ static ssize_t filter_mirror_receive_iov(NetFilterState *nf,
>       MirrorState *s = FILTER_MIRROR(nf);
>       int ret;
>   
> -    ret = filter_mirror_send(&s->chr_out, iov, iovcnt);
> +    ret = filter_mirror_send(s, iov, iovcnt);
>       if (ret) {
>           error_report("filter_mirror_send failed(%s)", strerror(-ret));
>       }
> @@ -164,7 +195,7 @@ static ssize_t filter_redirector_receive_iov(NetFilterState 
> *nf,
>       int ret;
>   
>       if (qemu_chr_fe_get_driver(&s->chr_out)) {
> -        ret = filter_mirror_send(&s->chr_out, iov, iovcnt);
> +        ret = filter_mirror_send(s, iov, iovcnt);
>           if (ret) {
>               error_report("filter_mirror_send failed(%s)", strerror(-ret));
>           }
> @@ -308,6 +339,13 @@ static char *filter_mirror_get_outdev(Object *obj, Error 
> **errp)
>       return g_strdup(s->outdev);
>   }
>   
> +static bool filter_mirror_get_vnet_hdr(Object *obj, Error **errp)
> +{
> +    MirrorState *s = FILTER_MIRROR(obj);
> +
> +    return s->vnet_hdr;
> +}
> +
>   static void
>   filter_mirror_set_outdev(Object *obj, const char *value, Error **errp)
>   {
> @@ -322,6 +360,15 @@ filter_mirror_set_outdev(Object *obj, const char *value, 
> Error **errp)
>       }
>   }
>   
> +static void filter_mirror_set_vnet_hdr(Object *obj,
> +                                       bool value,
> +                                       Error **errp)
> +{
> +    MirrorState *s = FILTER_MIRROR(obj);
> +
> +    s->vnet_hdr = value;
> +}
> +
>   static char *filter_redirector_get_outdev(Object *obj, Error **errp)
>   {
>       MirrorState *s = FILTER_REDIRECTOR(obj);
> @@ -340,8 +387,20 @@ filter_redirector_set_outdev(Object *obj, const char 
> *value, Error **errp)
>   
>   static void filter_mirror_init(Object *obj)
>   {
> +    MirrorState *s = FILTER_MIRROR(obj);
> +
>       object_property_add_str(obj, "outdev", filter_mirror_get_outdev,
>                               filter_mirror_set_outdev, NULL);
> +
> +    /*
> +     * The vnet_hdr is disabled by default, if you want to enable
> +     * this option, you must enable all the option on related modules
> +     * (like other filter or colo-compare).
> +     */

This comment makes sense for docs but is useless here, let code explain 
itself.

Thanks

> +    s->vnet_hdr = false;
> +    object_property_add_bool(obj, "vnet_hdr_support",
> +                             filter_mirror_get_vnet_hdr,
> +                             filter_mirror_set_vnet_hdr, NULL);
>   }
>   
>   static void filter_redirector_init(Object *obj)
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 70c0ded..5c09fae 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4024,10 +4024,9 @@ queue @var{all|rx|tx} is an option that can be applied 
> to any netfilter.
>   @option{tx}: the filter is attached to the transmit queue of the netdev,
>                where it will receive packets sent by the netdev.
>   
> address@hidden -object filter-mirror,address@hidden,address@hidden,address@hidden,address@hidden|rx|tx}]
> address@hidden -object 
> filter-mirror,address@hidden,address@hidden,address@hidden,address@hidden|rx|tx}[,vnet_hdr_support]
>   
> -filter-mirror on netdev @var{netdevid},mirror net packet to chardev
> address@hidden
> +filter-mirror on netdev @var{netdevid},mirror net packet to address@hidden, if 
> have the vnet_hdr_support flag, filter-mirror will mirror packet with 
> vnet_hdr_len.
>   
>   @item -object filter-redirector,address@hidden,address@hidden,address@hidden,
>   address@hidden,address@hidden|rx|tx}]