[SRU][O][PATCH 3/3] virtio_net: ensure netdev_tx_reset_queue is called on tx ring resize

[Koichiro Den]

BugLink: https://bugs.launchpad.net/bugs/2089684

virtnet_tx_resize() flushes remaining tx skbs, requiring DQL counters to
be reset when flushing has actually occurred. Add
virtnet_sq_free_unused_buf_done() as a callback for virtqueue_reset() to
handle this.

Fixes: c8bd1f7f3e61 ("virtio_net: add support for Byte Queue Limits")
Cc: <stable at vger.kernel.org> # v6.11+
Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
Acked-by: Jason Wang <jasowang at redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Signed-off-by: Paolo Abeni <pabeni at redhat.com>
(backported from commit 1480f0f61b675567ca5d0943d6ef2e39172dcafd linux-next)
[koichiroden: adjusted context due to missing unrelated commits]
Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
---
 drivers/net/virtio_net.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 905e84b10abe..fe1e59a4dcf6 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -501,6 +501,7 @@ struct virtio_net_common_hdr {
 };
 
 static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
+static void virtnet_sq_free_unused_buf_done(struct virtqueue *vq);
 static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
 			       struct net_device *dev,
 			       unsigned int *xdp_xmit,
@@ -3202,7 +3203,8 @@ static int virtnet_tx_resize(struct virtnet_info *vi, struct send_queue *sq,
 
 	virtnet_tx_pause(vi, sq);
 
-	err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf, NULL);
+	err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf,
+			       virtnet_sq_free_unused_buf_done);
 	if (err)
 		netdev_err(vi->dev, "resize tx fail: tx queue index: %d err: %d\n", qindex, err);
 
@@ -5929,6 +5931,14 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
 		xdp_return_frame(ptr_to_xdp(buf));
 }
 
+static void virtnet_sq_free_unused_buf_done(struct virtqueue *vq)
+{
+	struct virtnet_info *vi = vq->vdev->priv;
+	int i = vq2txq(vq);
+
+	netdev_tx_reset_queue(netdev_get_tx_queue(vi->dev, i));
+}
+
 static void free_unused_bufs(struct virtnet_info *vi)
 {
 	void *buf;
-- 
2.43.0