[PATCH net V2] virtio-net: set queues after driver_ok

[PATCH net V2] virtio-net: set queues after driver_ok

[Jason Wang]

Commit 25266128fe16 ("virtio-net: fix race between set queues and
probe") tries to fix the race between set queues and probe by calling
_virtnet_set_queues() before DRIVER_OK is set. This violates virtio
spec. Fixing this by setting queues after virtio_device_ready().

Note that rtnl needs to be held for userspace requests to change the
number of queues. So we are serialized in this way.

Fixes: 25266128fe16 ("virtio-net: fix race between set queues and probe")
Reported-by: Dragos Tatulea <dtatulea@nvidia.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
The patch is needed for -stable.
Changes since V1: Tweak the commit log.
---
 drivers/net/virtio_net.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1270c8d23463..ff03921e46df 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -4219,8 +4219,6 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (vi->has_rss || vi->has_rss_hash_report)
 		virtnet_init_default_rss(vi);
 
-	_virtnet_set_queues(vi, vi->curr_queue_pairs);
-
 	/* serialize netdev register + virtio_device_ready() with ndo_open() */
 	rtnl_lock();
 
@@ -4233,6 +4231,8 @@ static int virtnet_probe(struct virtio_device *vdev)
 
 	virtio_device_ready(vdev);
 
+	_virtnet_set_queues(vi, vi->curr_queue_pairs);
+
 	/* a random MAC address has been assigned, notify the device.
 	 * We don't fail probe if VIRTIO_NET_F_CTRL_MAC_ADDR is not there
 	 * because many devices work fine without getting MAC explicitly
-- 
2.39.3

Re: [PATCH net V2] virtio-net: set queues after driver_ok

[Jakub Kicinski]

On Wed,  9 Aug 2023 23:12:56 -0400 Jason Wang wrote:
> Commit 25266128fe16 ("virtio-net: fix race between set queues and
> probe") tries to fix the race between set queues and probe by calling
> _virtnet_set_queues() before DRIVER_OK is set. This violates virtio
> spec. Fixing this by setting queues after virtio_device_ready().
> 
> Note that rtnl needs to be held for userspace requests to change the
> number of queues. So we are serialized in this way.

FTR this appears to have been applied yesterday by DaveM. Thanks!

Re: [PATCH net V2] virtio-net: set queues after driver_ok

[Like Xu]

On 10/8/2023 11:12 am, Jason Wang wrote:
> Commit 25266128fe16 ("virtio-net: fix race between set queues and
> probe") tries to fix the race between set queues and probe by calling
> _virtnet_set_queues() before DRIVER_OK is set. This violates virtio
> spec. Fixing this by setting queues after virtio_device_ready().
> 
> Note that rtnl needs to be held for userspace requests to change the
> number of queues. So we are serialized in this way.
> 
> Fixes: 25266128fe16 ("virtio-net: fix race between set queues and probe")
> Reported-by: Dragos Tatulea <dtatulea@nvidia.com>

I had the same issue to report and this fix helped me out.
Tested-by: Like Xu <likexu@tencent.com>

> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> The patch is needed for -stable.
> Changes since V1: Tweak the commit log.
> ---
>   drivers/net/virtio_net.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 1270c8d23463..ff03921e46df 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -4219,8 +4219,6 @@ static int virtnet_probe(struct virtio_device *vdev)
>   	if (vi->has_rss || vi->has_rss_hash_report)
>   		virtnet_init_default_rss(vi);
>   
> -	_virtnet_set_queues(vi, vi->curr_queue_pairs);
> -
>   	/* serialize netdev register + virtio_device_ready() with ndo_open() */
>   	rtnl_lock();
>   
> @@ -4233,6 +4231,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>   
>   	virtio_device_ready(vdev);
>   
> +	_virtnet_set_queues(vi, vi->curr_queue_pairs);
> +
>   	/* a random MAC address has been assigned, notify the device.
>   	 * We don't fail probe if VIRTIO_NET_F_CTRL_MAC_ADDR is not there
>   	 * because many devices work fine without getting MAC explicitly