On Wed, Apr 07, 2010 at 05:00:39PM +0800, xiaohui.xin@xxxxxxxxx wrote:
> From: Xin Xiaohui <xiaohui.xin@xxxxxxxxx>
>
> ---
>
> Michael,
> Thanks a lot for the explanation. I have drafted a patch for the qemu write
> after I looked into tun driver. Does it do in right way?
>
> Thanks
> Xiaohui
>
> drivers/vhost/mpassthru.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 45 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/vhost/mpassthru.c b/drivers/vhost/mpassthru.c
> index e9449ac..1cde097 100644
> --- a/drivers/vhost/mpassthru.c
> +++ b/drivers/vhost/mpassthru.c
> @@ -1065,6 +1065,49 @@ static unsigned int mp_chr_poll(struct file *file, poll_table * wait)
> return mask;
> }
>
> +static ssize_t mp_chr_aio_write(struct kiocb *iocb, const struct iovec *iov,
> + unsigned long count, loff_t pos)
> +{
> + struct file *file = iocb->ki_filp;
> + struct mp_struct *mp = mp_get(file->private_data);
> + struct sock *sk = mp->socket.sk;
> + struct sk_buff *skb;
> + int len, err;
> + ssize_t result;
> +
> + if (!mp)
> + return -EBADFD;
> +
Can this happen? When?
> + /* currently, async is not supported */
> + if (!is_sync_kiocb(iocb))
> + return -EFAULT;
Really necessary? I think do_sync_write handles all this.
> +
> + len = iov_length(iov, count);
> + skb = sock_alloc_send_skb(sk, len + NET_IP_ALIGN,
> + file->f_flags & O_NONBLOCK, &err);
> +
> + if (!skb)
> + return -EFAULT;
Surely not EFAULT. -EAGAIN?
> +
> + skb_reserve(skb, NET_IP_ALIGN);
> + skb_put(skb, len);
> +
> + if (skb_copy_datagram_from_iovec(skb, 0, iov, 0, len)) {
> + kfree_skb(skb);
> + return -EFAULT;
> + }
> + skb_set_network_header(skb, ETH_HLEN);
Is this really right or necessary? Also,
probably need to check that length is at least ETH_ALEN before
doing this.
> + skb->protocol = *((__be16 *)(skb->data) + ETH_ALEN);
eth_type_trans?
> + skb->dev = mp->dev;
> +
> + dev_queue_xmit(skb);
> + mp->dev->stats.tx_packets++;
> + mp->dev->stats.tx_bytes += len;
Doesn't the hard start xmit function for the device
increment the counters?
> +
> + mp_put(mp);
> + return result;
> +}
> +
> static int mp_chr_close(struct inode *inode, struct file *file)
> {
> struct mp_file *mfile = file->private_data;
> @@ -1084,6 +1127,8 @@ static int mp_chr_close(struct inode *inode, struct file *file)
> static const struct file_operations mp_fops = {
> .owner = THIS_MODULE,
> .llseek = no_llseek,
> + .write = do_sync_write,
> + .aio_write = mp_chr_aio_write,
> .poll = mp_chr_poll,
> .unlocked_ioctl = mp_chr_ioctl,
> .open = mp_chr_open,
> --
> 1.5.4.4
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