[PATCH net-next v3 3/6] virtio_net: Add a lock for the command VQ.

[Daniel Jurgens <danielj@nvidia.com>]

The command VQ will no longer be protected by the RTNL lock. Use a
spinlock to protect the control buffer header and the VQ.

Signed-off-by: Daniel Jurgens <danielj@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
---
 drivers/net/virtio_net.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0ee192b45e1e..d02f83a919a7 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -282,6 +282,7 @@ struct virtnet_info {
 
 	/* Has control virtqueue */
 	bool has_cvq;
+	spinlock_t cvq_lock;
 
 	/* Host can handle any s/g split between our header and packet data */
 	bool any_header_sg;
@@ -2529,6 +2530,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
 	/* Caller should know better */
 	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
 
+	guard(spinlock)(&vi->cvq_lock);
 	vi->ctrl->status = ~0;
 	vi->ctrl->hdr.class = class;
 	vi->ctrl->hdr.cmd = cmd;
@@ -4818,8 +4820,10 @@ static int virtnet_probe(struct virtio_device *vdev)
 	    virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
 		vi->any_header_sg = true;
 
-	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
 		vi->has_cvq = true;
+		spin_lock_init(&vi->cvq_lock);
+	}
 
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
 		mtu = virtio_cread16(vdev,
-- 
2.42.0