From: Jason Wang Date: Wed, 2 May 2012 03:42:06 +0000 (+0800) Subject: macvtap: zerocopy: set SKBTX_DEV_ZEROCOPY only when skb is built successfully X-Git-Tag: v3.2.24~90 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cc64214d05941d09bb9f80051a1949a7223b8ab7;p=thirdparty%2Fkernel%2Fstable.git macvtap: zerocopy: set SKBTX_DEV_ZEROCOPY only when skb is built successfully commit 01d6657b388438def19c8baaea28e742b6ed32ec upstream. 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 Signed-off-by: Michael S. Tsirkin Signed-off-by: Ben Hutchings --- diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index f217247c9b9c3..7fecd667b4940 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -698,10 +698,9 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, if (!skb) goto err; - if (zerocopy) { + if (zerocopy) 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, len); if (err) @@ -720,8 +719,10 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, rcu_read_lock_bh(); vlan = rcu_dereference_bh(q->vlan); /* 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)->tx_flags |= SKBTX_DEV_ZEROCOPY; + } if (vlan) macvlan_start_xmit(skb, vlan->dev); else