From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH] vhost_net: clear msg.control for non-zerocopy case during tx Date: Thu, 06 Jun 2013 21:12:50 +0400 Message-ID: <51B0C312.7020903@cogentembedded.com> References: <1370418046-11851-1-git-send-email-jasowang@redhat.com> <51AF40CB.5030101@cogentembedded.com> <51B00190.2050307@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mst@redhat.com To: Jason Wang Return-path: In-Reply-To: <51B00190.2050307@redhat.com> 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 List-Id: netdev.vger.kernel.org Hello. On 06/06/2013 07:27 AM, Jason Wang wrote: >>> 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 >>> --- >>> drivers/vhost/net.c | 3 ++- >>> 1 files changed, 2 insertions(+), 1 deletions(-) >>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >>> index 2b51e23..b07d96b 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 >> You have to use {} on the *else* branch if you have it of the *if* >> branch (and vice versa), according to Documentation/CodingStyle. > checkpatch.pl didn't complain this, will send v2. Yes, this check is what it seems to lack still. > Thanks > WBR, Sergei