Re: [Qemu-devel] [PATCH] virtio-net: don't update mac_table in error state

[Vlad Yasevich]

On 11/10/2013 10:48 PM, Amos Kong wrote:
> mac_table was always cleaned up first in handling
> VIRTIO_NET_CTRL_MAC_TABLE_SET command, and we din't recover
> mac_table content in error state, it's not correct.
>
> This patch makes all the changes in temporal variables,
> only update the real mac_table if everything is ok.
> We won't change mac_table in error state, so rxfilter
> notification isn't needed.
>
> This patch also fixed same problame in
>   http://lists.nongnu.org/archive/html/qemu-devel/2013-11/msg01188.html
>   (not merge)
>
> I will send patch for virtio spec to clarifying this change.
>
> Signed-off-by: Amos Kong <address@hidden>
> ---
>   hw/net/virtio-net.c | 34 ++++++++++++++++++++--------------
>   1 file changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 22dbd05..880fa4a 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -610,11 +610,11 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t 
> cmd,
>           return VIRTIO_NET_ERR;
>       }
>
> -    n->mac_table.in_use = 0;
> -    n->mac_table.first_multi = 0;
> -    n->mac_table.uni_overflow = 0;
> -    n->mac_table.multi_overflow = 0;
> -    memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
> +    int in_use = 0;
> +    int first_multi = 0;
> +    uint8_t uni_overflow = 0;
> +    uint8_t multi_overflow = 0;
> +    uint8_t *macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);

I am not sure what the practice is for mixing declarations with code in 
qemu.  Can't find anything in the docs.

Otherwise, looks good to me.

Reviewed-by: Vlad Yasevich <address@hidden>

-vlad

>       s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
>                      sizeof(mac_data.entries));
> @@ -629,19 +629,19 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t 
> cmd,
>       }
>
>       if (mac_data.entries <= MAC_TABLE_ENTRIES) {
> -        s = iov_to_buf(iov, iov_cnt, 0, n->mac_table.macs,
> +        s = iov_to_buf(iov, iov_cnt, 0, macs,
>                          mac_data.entries * ETH_ALEN);
>           if (s != mac_data.entries * ETH_ALEN) {
>               goto error;
>           }
> -        n->mac_table.in_use += mac_data.entries;
> +        in_use += mac_data.entries;
>       } else {
> -        n->mac_table.uni_overflow = 1;
> +        uni_overflow = 1;
>       }
>
>       iov_discard_front(&iov, &iov_cnt, mac_data.entries * ETH_ALEN);
>
> -    n->mac_table.first_multi = n->mac_table.in_use;
> +    first_multi = in_use;
>
>       s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
>                      sizeof(mac_data.entries));
> @@ -656,23 +656,29 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t 
> cmd,
>           goto error;
>       }
>
> -    if (n->mac_table.in_use + mac_data.entries <= MAC_TABLE_ENTRIES) {
> -        s = iov_to_buf(iov, iov_cnt, 0, n->mac_table.macs,
> +    if (in_use + mac_data.entries <= MAC_TABLE_ENTRIES) {
> +        s = iov_to_buf(iov, iov_cnt, 0, &macs[in_use * ETH_ALEN],
>                          mac_data.entries * ETH_ALEN);
>           if (s != mac_data.entries * ETH_ALEN) {
>               goto error;
>           }
> -        n->mac_table.in_use += mac_data.entries;
> +        in_use += mac_data.entries;
>       } else {
> -        n->mac_table.multi_overflow = 1;
> +        multi_overflow = 1;
>       }
>
> +    n->mac_table.in_use = in_use;
> +    n->mac_table.first_multi = first_multi;
> +    n->mac_table.uni_overflow = uni_overflow;
> +    n->mac_table.multi_overflow = multi_overflow;
> +    memcpy(n->mac_table.macs, macs, MAC_TABLE_ENTRIES * ETH_ALEN);
> +    g_free(macs);
>       rxfilter_notify(nc);
>
>       return VIRTIO_NET_OK;
>
>   error:
> -    rxfilter_notify(nc);
> +    g_free(macs);
>       return VIRTIO_NET_ERR;
>   }