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macvtap: zerocopy: set SKBTX_DEV_ZEROCOPY only when skb is built successfully 

Current the SKBTX_DEV_ZEROCOPY is set unconditionally after
zerocopy_sg_from_iovec(), this would lead NULL pointer when macvtap
fails to build zerocopy skb because destructor_arg was not
initialized. Solve this by set this flag after the skb were built
successfully.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Jason Wang 2012-05-02 11:42:06 +08:00 committed by Michael S. Tsirkin
parent 02ce04bb3d
commit 01d6657b38
1 changed files with 5 additions and 4 deletions
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9
drivers/net/macvtap.c
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@ -699,10 +699,9 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
if (!skb) if (!skb)
goto err; goto err;
if (zerocopy) { if (zerocopy)
err = zerocopy_sg_from_iovec(skb, iv, vnet_hdr_len, count); err = zerocopy_sg_from_iovec(skb, iv, vnet_hdr_len, count);
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; else
} else
err = skb_copy_datagram_from_iovec(skb, 0, iv, vnet_hdr_len, err = skb_copy_datagram_from_iovec(skb, 0, iv, vnet_hdr_len,
len); len);
if (err) if (err)
@ -721,8 +720,10 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
rcu_read_lock_bh(); rcu_read_lock_bh();
vlan = rcu_dereference_bh(q->vlan); vlan = rcu_dereference_bh(q->vlan);
/* copy skb_ubuf_info for callback when skb has no error */ /* copy skb_ubuf_info for callback when skb has no error */
if (zerocopy) if (zerocopy) {
skb_shinfo(skb)->destructor_arg = m->msg_control; skb_shinfo(skb)->destructor_arg = m->msg_control;
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
}
if (vlan) if (vlan)
macvlan_start_xmit(skb, vlan->dev); macvlan_start_xmit(skb, vlan->dev);
else else