On Wed, Nov 30, 2016 at 01:17:52PM +0800, Jason Wang wrote:
> We trigger uarg->callback() immediately after we decide do datacopy
> even if caller want to do zerocopy. This will cause the callback
> (vhost_net_zerocopy_callback) decrease the refcount. But when we meet
> an error afterwards, the error handling in vhost handle_tx() will try
> to decrease it again. This is wrong and fix this by delay the
> uarg->callback() until we're sure there's no errors.
>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> The patch is needed for -stable.
> ---
> drivers/net/macvtap.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index bceca28..7869b06 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -742,13 +742,8 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q,
> struct msghdr *m,
>
> if (zerocopy)
> err = zerocopy_sg_from_iter(skb, from);
> - else {
> + else
> err = skb_copy_datagram_from_iter(skb, 0, from, len);
> - if (!err && m && m->msg_control) {
> - struct ubuf_info *uarg = m->msg_control;
> - uarg->callback(uarg, false);
> - }
> - }
>
> if (err)
> goto err_kfree;
> @@ -779,7 +774,11 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q,
> struct msghdr *m,
> skb_shinfo(skb)->destructor_arg = m->msg_control;
> skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
> skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
> + } else if (m && m->msg_control) {
> + struct ubuf_info *uarg = m->msg_control;
> + uarg->callback(uarg, false);
> }
> +
> if (vlan) {
> skb->dev = vlan->dev;
> dev_queue_xmit(skb);
> --
> 2.7.4
