From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [PATCH net 2/2] macvtap: handle ubuf refcount correctly when meet erros Date: Wed, 30 Nov 2016 13:17:52 +0800 Message-ID: <1480483072-14201-2-git-send-email-jasowang@redhat.com> References: <1480483072-14201-1-git-send-email-jasowang@redhat.com> Cc: mst@redhat.com, wangyunjian@huawei.com, Jason Wang To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1480483072-14201-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 --- 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