Commit 1cb81756 authored Mar 26, 2018 by Jason Wang Committed by Greg Kroah-Hartman Apr 13, 2018

vhost_net: add missing lock nesting notation




[ Upstream commit aaa3149bbee9ba9b4e6f0bd6e3e7d191edeae942 ]

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: 03088137 ("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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e0cfa0d3

drivers/vhost/net.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -524,7 +524,7 @@ 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();
		@@ -657,7 +657,7 @@ 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;