* [PATCH] vhost: fix read vs write lock mismatch
@ 2024-11-18 16:24 Stephen Hemminger
2024-11-25 11:14 ` David Marchand
0 siblings, 1 reply; 2+ messages in thread
From: Stephen Hemminger @ 2024-11-18 16:24 UTC (permalink / raw)
To: dev
Cc: Stephen Hemminger, david.marchand, stable, Maxime Coquelin,
Chenbo Xia, Eelco Chaudron
If lock is acquired for write, it must be released for write
or a deadlock is likely.
Bugzilla ID: 1582
Fixes: 9fc93a1e2320 ("vhost: fix virtqueue access check in datapath")
Cc: david.marchand@redhat.com
Cc: stable@dpdk.org
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
lib/vhost/virtio_net.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index 298a5dae74..d764d4bc6a 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -2538,7 +2538,7 @@ virtio_dev_rx_async_submit(struct virtio_net *dev, struct vhost_virtqueue *vq,
if (unlikely(!vq->access_ok)) {
vhost_user_iotlb_rd_unlock(vq);
- rte_rwlock_read_unlock(&vq->access_lock);
+ rte_rwlock_write_unlock(&vq->access_lock);
virtio_dev_vring_translate(dev, vq);
goto out_no_unlock;
--
2.45.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] vhost: fix read vs write lock mismatch
2024-11-18 16:24 [PATCH] vhost: fix read vs write lock mismatch Stephen Hemminger
@ 2024-11-25 11:14 ` David Marchand
0 siblings, 0 replies; 2+ messages in thread
From: David Marchand @ 2024-11-25 11:14 UTC (permalink / raw)
To: Stephen Hemminger
Cc: dev, stable, Maxime Coquelin, Chenbo Xia, Eelco Chaudron
On Mon, Nov 18, 2024 at 5:24 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> If lock is acquired for write, it must be released for write
> or a deadlock is likely.
>
> Bugzilla ID: 1582
> Fixes: 9fc93a1e2320 ("vhost: fix virtqueue access check in datapath")
> Cc: david.marchand@redhat.com
> Cc: stable@dpdk.org
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> lib/vhost/virtio_net.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index 298a5dae74..d764d4bc6a 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -2538,7 +2538,7 @@ virtio_dev_rx_async_submit(struct virtio_net *dev, struct vhost_virtqueue *vq,
>
> if (unlikely(!vq->access_ok)) {
> vhost_user_iotlb_rd_unlock(vq);
> - rte_rwlock_read_unlock(&vq->access_lock);
> + rte_rwlock_write_unlock(&vq->access_lock);
A write lock is taken earlier, because virtio_dev_rx_async_submit_*
need it for access to vq->async (as opposed to the sync code that only
takes read lock).
Here, no need to release/take again all locks.
A simpler fix is to directly call vring_translate(dev, vq).
--
David Marchand
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