Re: [PATCH net-next v2 4/5] virtio_ring: add 'flushed' as an argument to virtqueue_reset()

On Tue, Dec 3, 2024 at 3:31 PM Koichiro Den koichiro.den@canonical.com wrote:

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 koichiro.den@canonical.com

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?

Thanks