Re: [PATCH net] vhost_net: add missing lock nesting notation
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2018-03-26 13:24:23
Also in:
kvm, lkml, netdev
On Mon, Mar 26, 2018 at 04:10:23PM +0800, Jason Wang wrote:
We try to hold TX virtqueue mutex in vhost_net_rx_peek_head_len()
after RX virtqueue mutex is held in handle_rx(). This requires an
appropriate lock nesting notation to calm down deadlock detector.
Fixes: 0308813724606 ("vhost_net: basic polling support")
Reported-by: syzbot+7f073540b1384a614e09@syzkaller.appspotmail.com
Signed-off-by: Jason Wang <jasowang@redhat.com>Acked-by: Michael S. Tsirkin <mst@redhat.com>
quoted hunk ↗ jump to hunk
--- drivers/vhost/net.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 8139bc7..12bcfba 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c@@ -630,7 +630,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk) if (!len && vq->busyloop_timeout) { /* Both tx vq and rx socket were polled here */ - mutex_lock(&vq->mutex); + mutex_lock_nested(&vq->mutex, 1); vhost_disable_notify(&net->dev, vq); preempt_disable();@@ -763,7 +763,7 @@ static void handle_rx(struct vhost_net *net) struct iov_iter fixup; __virtio16 num_buffers; - mutex_lock(&vq->mutex); + mutex_lock_nested(&vq->mutex, 0); sock = vq->private_data; if (!sock) goto out;-- 2.7.4