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


From: Jason Wang
Subject: Re: [Qemu-devel] [PATCH] virtio-net: don't update mac_table in error state
Date: Wed, 13 Nov 2013 15:19:36 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0

On 11/11/2013 11:48 AM, 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>

Acked-by: Jason Wang <address@hidden>

In the future, maybe we can allocate the mac_table dynamically instead
of embed it in VirtIONet. Then we can just does a pointer swap and
gfree() and can save a memcpy() here.
> ---
>  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);
>  
>      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;
>  }
>  




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