* [PATCH net] vhost_net: add missing lock nesting notation
@ 2018-03-26 8:10 Jason Wang
2018-03-26 13:24 ` Michael S. Tsirkin
2018-03-26 16:59 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Jason Wang @ 2018-03-26 8:10 UTC (permalink / raw)
To: mst, kvm, virtualization, netdev, linux-kernel
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>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH net] vhost_net: add missing lock nesting notation
2018-03-26 8:10 [PATCH net] vhost_net: add missing lock nesting notation Jason Wang
@ 2018-03-26 13:24 ` Michael S. Tsirkin
2018-03-26 16:59 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Michael S. Tsirkin @ 2018-03-26 13:24 UTC (permalink / raw)
To: Jason Wang; +Cc: netdev, linux-kernel, kvm, virtualization
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>
> ---
> 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
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH net] vhost_net: add missing lock nesting notation
2018-03-26 8:10 [PATCH net] vhost_net: add missing lock nesting notation Jason Wang
2018-03-26 13:24 ` Michael S. Tsirkin
@ 2018-03-26 16:59 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2018-03-26 16:59 UTC (permalink / raw)
To: jasowang; +Cc: mst, kvm, virtualization, netdev, linux-kernel
From: Jason Wang <jasowang@redhat.com>
Date: Mon, 26 Mar 2018 16:10:23 +0800
> 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>
Applied and queued up for -stable, thanks Jason.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-03-26 8:10 [PATCH net] vhost_net: add missing lock nesting notation Jason Wang
2018-03-26 13:24 ` Michael S. Tsirkin
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