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tun: handle ubuf refcount correctly when meet errors

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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.

Reported-by: wangyunjian <wangyunjian@huawei.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2016-11-30 13:17:51 +08:00 committed by David S. Miller
parent 4ccfd6383a
commit af1cc7a2b8
1 changed files with 4 additions and 6 deletions
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10
drivers/net/tun.c
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@ -1246,13 +1246,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (zerocopy)
err = zerocopy_sg_from_iter(skb, from);
else {
else
err = skb_copy_datagram_from_iter(skb, 0, from, len);
if (!err && msg_control) {
struct ubuf_info *uarg = msg_control;
uarg->callback(uarg, false);
}
}
if (err) {
this_cpu_inc(tun->pcpu_stats->rx_dropped);
@ -1298,6 +1293,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_shinfo(skb)->destructor_arg = msg_control;
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
} else if (msg_control) {
struct ubuf_info *uarg = msg_control;
uarg->callback(uarg, false);
}
skb_reset_network_header(skb);