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

[Koichiro Den <koichiro.den@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
---
 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;
 
 	if (vq->packed_ring)
 		virtqueue_reinit_packed(vq);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 878feda08af9..e5072d64a364 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -112,7 +112,8 @@ int virtqueue_resize(struct virtqueue *vq, u32 num,
 		     void (*recycle)(struct virtqueue *vq, void *buf),
 		     bool *flushed);
 int virtqueue_reset(struct virtqueue *vq,
-		    void (*recycle)(struct virtqueue *vq, void *buf));
+		    void (*recycle)(struct virtqueue *vq, void *buf),
+		    bool *flushed);
 
 struct virtio_admin_cmd {
 	__le16 opcode;
-- 
2.43.0