On Wed, Dec 04, 2024 at 10:49:02AM +0800, Jason Wang wrote:

On Tue, Dec 3, 2024 at 3:31 PM Koichiro Den [off-list ref] wrote:

quoted

When virtqueue_reset() has actually recycled all unused buffers,
additional work may be required in some cases. Relying solely on its
return status is fragile, so introduce a new argument 'flushed' to
explicitly indicate whether it has really occurred.

Signed-off-by: Koichiro Den <redacted>
---
 drivers/net/virtio_net.c     | 6 ++++--
 drivers/virtio/virtio_ring.c | 6 +++++-
 include/linux/virtio.h       | 3 ++-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0103d7990e44..d5240a03b7d6 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -5695,6 +5695,7 @@ static int virtnet_rq_bind_xsk_pool(struct virtnet_info *vi, struct receive_queu
                                    struct xsk_buff_pool *pool)
 {
        int err, qindex;
+       bool flushed;

        qindex = rq - vi->rq;

@@ -5713,7 +5714,7 @@ static int virtnet_rq_bind_xsk_pool(struct virtnet_info *vi, struct receive_queu

        virtnet_rx_pause(vi, rq);

-       err = virtqueue_reset(rq->vq, virtnet_rq_unmap_free_buf);
+       err = virtqueue_reset(rq->vq, virtnet_rq_unmap_free_buf, &flushed);
        if (err) {
                netdev_err(vi->dev, "reset rx fail: rx queue index: %d err: %d\n", qindex, err);

@@ -5737,12 +5738,13 @@ static int virtnet_sq_bind_xsk_pool(struct virtnet_info *vi,
                                    struct xsk_buff_pool *pool)
 {
        int err, qindex;
+       bool flushed;

        qindex = sq - vi->sq;

        virtnet_tx_pause(vi, sq);

-       err = virtqueue_reset(sq->vq, virtnet_sq_free_unused_buf);
+       err = virtqueue_reset(sq->vq, virtnet_sq_free_unused_buf, &flushed);
        if (err) {
                netdev_err(vi->dev, "reset tx fail: tx queue index: %d err: %d\n", qindex, err);
                pool = NULL;

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 34a068d401ec..b522ef798946 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c

@@ -2828,6 +2828,7 @@ EXPORT_SYMBOL_GPL(virtqueue_resize);
  * virtqueue_reset - detach and recycle all unused buffers
  * @_vq: the struct virtqueue we're talking about.
  * @recycle: callback to recycle unused buffers
+ * @flushed: whether or not unused buffers are all flushed
  *
  * Caller must ensure we don't call this with other virtqueue operations
  * at the same time (except where noted).

@@ -2839,14 +2840,17 @@ EXPORT_SYMBOL_GPL(virtqueue_resize);
  * -EPERM: Operation not permitted
  */
 int virtqueue_reset(struct virtqueue *_vq,
-                   void (*recycle)(struct virtqueue *vq, void *buf))
+                   void (*recycle)(struct virtqueue *vq, void *buf),
+                   bool *flushed)
 {
        struct vring_virtqueue *vq = to_vvq(_vq);
        int err;

+       *flushed = false;
        err = virtqueue_disable_and_recycle(_vq, recycle);
        if (err)
                return err;
+       *flushed = true;

This makes me think if it would be easier if we just find a way to
reset the tx queue inside virtqueue_disable_and_recycle().

For example, introducing a recycle_done callback?

It sounds reasonable and much cleaner. I'll prepare and send v3 shortly.
Thanks for the review.

-Koichiro Den

Thanks