Re: [Qemu-devel] [PATCH V3 05/10] net/net.c: Add vnet header length to SocketReadState

[Jason Wang <jasowang@redhat.com>]

On 2017年04月28日 17:47, Zhang Chen wrote:
> Address Jason Wang's comments add vnet header length to SocketReadState.

Instead of saying this, you can add "Suggested-by: Jason Wang 
<jasowang@redhat.com>" above your sign-off.

> So we change net_fill_rstate() to read
> struct  {int size; int vnet_hdr_len; const uint8_t buf[];}.

This makes me thinking about the backward compatibility. I think we'd 
better try to keep it as much as possible. E.g how about pack 
vnet_hdr_len into higher bits of size?

Thanks

>
> Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
> ---
>   include/net/net.h |  4 +++-
>   net/net.c         | 24 ++++++++++++++++++++++--
>   2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/net.h b/include/net/net.h
> index 402d913..865cb98 100644
> --- a/include/net/net.h
> +++ b/include/net/net.h
> @@ -115,9 +115,11 @@ typedef struct NICState {
>   } NICState;
>   
>   struct SocketReadState {
> -    int state; /* 0 = getting length, 1 = getting data */
> +    /* 0 = getting length, 1 = getting vnet header length, 2 = getting data */
> +    int state;
>       uint32_t index;
>       uint32_t packet_len;
> +    uint32_t vnet_hdr_len;
>       uint8_t buf[NET_BUFSIZE];
>       SocketReadStateFinalize *finalize;
>   };
> diff --git a/net/net.c b/net/net.c
> index f69260f..5a6b5ac 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -1639,8 +1639,12 @@ int net_fill_rstate(SocketReadState *rs, const uint8_t *buf, int size)
>       unsigned int l;
>   
>       while (size > 0) {
> -        /* reassemble a packet from the network */
> -        switch (rs->state) { /* 0 = getting length, 1 = getting data */
> +        /* Reassemble a packet from the network.
> +         * 0 = getting length.
> +         * 1 = getting vnet header length.
> +         * 2 = getting data.
> +         */
> +        switch (rs->state) {
>           case 0:
>               l = 4 - rs->index;
>               if (l > size) {
> @@ -1658,6 +1662,22 @@ int net_fill_rstate(SocketReadState *rs, const uint8_t *buf, int size)
>               }
>               break;
>           case 1:
> +            l = 4 - rs->index;
> +            if (l > size) {
> +                l = size;
> +            }
> +            memcpy(rs->buf + rs->index, buf, l);
> +            buf += l;
> +            size -= l;
> +            rs->index += l;
> +            if (rs->index == 4) {
> +                /* got vnet header length */
> +                rs->vnet_hdr_len = ntohl(*(uint32_t *)rs->buf);
> +                rs->index = 0;
> +                rs->state = 2;
> +            }
> +            break;
> +        case 2:
>               l = rs->packet_len - rs->index;
>               if (l > size) {
>                   l = size;