From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752020Ab2DPGRD (ORCPT ); Mon, 16 Apr 2012 02:17:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1029 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751373Ab2DPGQ7 (ORCPT ); Mon, 16 Apr 2012 02:16:59 -0400 Subject: [PATCH 4/6] macvtap: zerocopy: set SKBTX_DEV_ZEROCOPY only when skb is built successfully To: netdev@vger.kernel.org, xma@us.ibm.com, davem@davemloft.net, linux-kernel@vger.kernel.org, mst@redhat.com From: Jason Wang Cc: ebiederm@xmission.com Date: Mon, 16 Apr 2012 14:08:16 +0800 Message-ID: <20120416060816.14140.42824.stgit@intel-e5620-16-2.englab.nay.redhat.com> In-Reply-To: <20120416060749.14140.19433.stgit@intel-e5620-16-2.englab.nay.redhat.com> References: <20120416060749.14140.19433.stgit@intel-e5620-16-2.englab.nay.redhat.com> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/net/macvtap.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index d197a78..c030468 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -699,10 +699,9 @@ 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) @@ -721,8 +720,10 @@ 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