From 4364d5f96eed7994a2c625bd9216656e55fba0cb Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 5 Jun 2013 15:40:46 +0800 Subject: vhost_net: clear msg.control for non-zerocopy case during tx 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 Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/vhost/net.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/vhost') diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 2b51e2336aa..b07d96b8c0d 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -436,7 +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); if (unlikely(err < 0)) { -- cgit v1.2.3-18-g5258