From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [PATCH V2] vhost_net: clear msg.control for non-zerocopy case during tx Date: Thu, 6 Jun 2013 11:24:02 +0800 Message-ID: <1370489042-14318-1-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: sergei.shtylyov@cogentembedded.com List-Id: virtualization@lists.linuxfoundation.org When we decide not use zero-copy, msg.control should be set to NULL otherwise macvtap/tap may set zerocopy callbacks which may decrease the kref of ubufs wrongly. Bug were introduced by commit cedb9bdce099206290a2bdd02ce47a7b253b6a84 (vhost-net: skip head management if no outstanding). This solves the following warnings: WARNING: at include/linux/kref.h:47 handle_tx+0x477/0x4b0 [vhost_net]() Modules linked in: vhost_net macvtap macvlan tun nfsd exportfs bridge stp llc openvswitch kvm_amd kvm bnx2 megaraid_sas [last unloaded: tun] CPU: 5 PID: 8670 Comm: vhost-8668 Not tainted 3.10.0-rc2+ #1566 Hardware name: Dell Inc. PowerEdge R715/00XHKG, BIOS 1.5.2 04/19/2011 ffffffffa0198323 ffff88007c9ebd08 ffffffff81796b73 ffff88007c9ebd48 ffffffff8103d66b 000000007b773e20 ffff8800779f0000 ffff8800779f43f0 ffff8800779f8418 000000000000015c 0000000000000062 ffff88007c9ebd58 Call Trace: [] dump_stack+0x19/0x1e [] warn_slowpath_common+0x6b/0xa0 [] warn_slowpath_null+0x15/0x20 [] handle_tx+0x477/0x4b0 [vhost_net] [] handle_tx_kick+0x10/0x20 [vhost_net] [] vhost_worker+0xfe/0x1a0 [vhost_net] [] ? vhost_attach_cgroups_work+0x30/0x30 [vhost_net] [] ? vhost_attach_cgroups_work+0x30/0x30 [vhost_net] [] kthread+0xc6/0xd0 [] ? kthread_freezable_should_stop+0x70/0x70 [] ret_from_fork+0x7c/0xb0 [] ? kthread_freezable_should_stop+0x70/0x70 Acked-by: Michael S. Tsirkin Signed-off-by: Jason Wang --- The patch is needed for -stable. Changes from v1: - code style issue fix --- drivers/vhost/net.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 2b51e23..518622d 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -436,6 +436,8 @@ static void handle_tx(struct vhost_net *net) kref_get(&ubufs->kref); } nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV; + } else { + msg.msg_control = NULL; } /* TODO: Check specific error and bomb out unless ENOBUFS? */ err = sock->ops->sendmsg(NULL, sock, &msg, len); -- 1.7.1