From: Jia He <justin.he@arm.com>
To: Stefan Hajnoczi <stefanha@redhat.com>,
Stefano Garzarella <sgarzare@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>
Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Kaly.Xin@arm.com, Jia He <justin.he@arm.com>
Subject: [PATCH] vhost: vsock: don't send pkt when vq is not started
Date: Thu, 30 Apr 2020 10:13:14 +0800 [thread overview]
Message-ID: <20200430021314.6425-1-justin.he@arm.com> (raw)
Ning Bo reported an abnormal 2-second gap when booting Kata container [1].
The unconditional timeout is caused by VSOCK_DEFAULT_CONNECT_TIMEOUT of
connect at client side. The vhost vsock client tries to connect an
initlizing virtio vsock server.
The abnormal flow looks like:
host-userspace vhost vsock guest vsock
============== =========== ============
connect() --------> vhost_transport_send_pkt_work() initializing
| vq->private_data==NULL
| will not be queued
V
schedule_timeout(2s)
vhost_vsock_start() <--------- device ready
set vq->private_data
wait for 2s and failed
connect() again vq->private_data!=NULL recv connecting pkt
1. host userspace sends a connect pkt, at that time, guest vsock is under
initializing, hence the vhost_vsock_start has not been called. So
vq->private_data==NULL, and the pkt is not been queued to send to guest.
2. then it sleeps for 2s
3. after guest vsock finishes initializing, vq->private_data is set.
4. When host userspace wakes up after 2s, send connecting pkt again,
everything is fine.
This fixes it by checking vq->private_data in vhost_transport_send_pkt,
and return at once if !vq->private_data. This makes user connect()
be returned with ECONNREFUSED.
After this patch, kata-runtime (with vsock enabled) boottime reduces from
3s to 1s on ThunderX2 arm64 server.
[1] https://github.com/kata-containers/runtime/issues/1917
Reported-by: Ning Bo <n.b@live.com>
Signed-off-by: Jia He <justin.he@arm.com>
---
drivers/vhost/vsock.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index e36aaf9ba7bd..67474334dd88 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -241,6 +241,7 @@ vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
{
struct vhost_vsock *vsock;
int len = pkt->len;
+ struct vhost_virtqueue *vq;
rcu_read_lock();
@@ -252,6 +253,13 @@ vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
return -ENODEV;
}
+ vq = &vsock->vqs[VSOCK_VQ_RX];
+ if (!vq->private_data) {
+ rcu_read_unlock();
+ virtio_transport_free_pkt(pkt);
+ return -ECONNREFUSED;
+ }
+
if (pkt->reply)
atomic_inc(&vsock->queued_replies);
--
2.17.1
next reply other threads:[~2020-04-30 2:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 2:13 Jia He [this message]
2020-04-30 8:26 ` [PATCH] vhost: vsock: don't send pkt when vq is not started Stefano Garzarella
2020-04-30 10:06 ` Justin He
2020-04-30 16:25 ` Stefano Garzarella
2020-04-30 19:43 ` Michael S. Tsirkin
2020-05-01 14:37 ` Stefano Garzarella
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