[PATCH net-next 4/5] virtio_ring: introduce virtqueue_get_dma_premapped()

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Introduce helper virtqueue_get_dma_premapped(), then the driver
can know whether dma unmap is needed.

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
 drivers/net/virtio/main.c       | 22 +++++++++-------------
 drivers/net/virtio/virtio_net.h |  3 ---
 drivers/virtio/virtio_ring.c    | 22 ++++++++++++++++++++++
 include/linux/virtio.h          |  1 +
 4 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
index 186b2cf5d8fc..4fbf612da235 100644
--- a/drivers/net/virtio/main.c
+++ b/drivers/net/virtio/main.c
@@ -483,7 +483,7 @@ static void *virtnet_rq_get_buf(struct virtnet_rq *rq, u32 *len, void **ctx)
 	void *buf;
 
 	buf = virtqueue_get_buf_ctx(rq->vq, len, ctx);
-	if (buf && rq->do_dma)
+	if (buf && virtqueue_get_dma_premapped(rq->vq))
 		virtnet_rq_unmap(rq, buf, *len);
 
 	return buf;
@@ -496,7 +496,7 @@ static void virtnet_rq_init_one_sg(struct virtnet_rq *rq, void *buf, u32 len)
 	u32 offset;
 	void *head;
 
-	if (!rq->do_dma) {
+	if (!virtqueue_get_dma_premapped(rq->vq)) {
 		sg_init_one(rq->sg, buf, len);
 		return;
 	}
@@ -526,7 +526,7 @@ static void *virtnet_rq_alloc(struct virtnet_rq *rq, u32 size, gfp_t gfp)
 
 	head = page_address(alloc_frag->page);
 
-	if (rq->do_dma) {
+	if (virtqueue_get_dma_premapped(rq->vq)) {
 		dma = head;
 
 		/* new pages */
@@ -580,12 +580,8 @@ static void virtnet_rq_set_premapped(struct virtnet_info *vi)
 	if (!vi->mergeable_rx_bufs && vi->big_packets)
 		return;
 
-	for (i = 0; i < vi->max_queue_pairs; i++) {
-		if (virtqueue_set_dma_premapped(vi->rq[i].vq))
-			continue;
-
-		vi->rq[i].do_dma = true;
-	}
+	for (i = 0; i < vi->max_queue_pairs; i++)
+		virtqueue_set_dma_premapped(vi->rq[i].vq);
 }
 
 static void free_old_xmit(struct virtnet_sq *sq, bool in_napi)
@@ -1643,7 +1639,7 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct virtnet_rq *rq,
 
 	err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
 	if (err < 0) {
-		if (rq->do_dma)
+		if (virtqueue_get_dma_premapped(rq->vq))
 			virtnet_rq_unmap(rq, buf, 0);
 		put_page(virt_to_head_page(buf));
 	}
@@ -1758,7 +1754,7 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
 	ctx = mergeable_len_to_ctx(len + room, headroom);
 	err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
 	if (err < 0) {
-		if (rq->do_dma)
+		if (virtqueue_get_dma_premapped(rq->vq))
 			virtnet_rq_unmap(rq, buf, 0);
 		put_page(virt_to_head_page(buf));
 	}
@@ -4007,7 +4003,7 @@ static void free_receive_page_frags(struct virtnet_info *vi)
 	int i;
 	for (i = 0; i < vi->max_queue_pairs; i++)
 		if (vi->rq[i].alloc_frag.page) {
-			if (vi->rq[i].do_dma && vi->rq[i].last_dma)
+			if (virtqueue_get_dma_premapped(vi->rq[i].vq) && vi->rq[i].last_dma)
 				virtnet_rq_unmap(&vi->rq[i], vi->rq[i].last_dma, 0);
 			put_page(vi->rq[i].alloc_frag.page);
 		}
@@ -4035,7 +4031,7 @@ static void virtnet_rq_free_unused_bufs(struct virtqueue *vq)
 	rq = &vi->rq[i];
 
 	while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) {
-		if (rq->do_dma)
+		if (virtqueue_get_dma_premapped(rq->vq))
 			virtnet_rq_unmap(rq, buf, 0);
 
 		virtnet_rq_free_buf(vi, rq, buf);
diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
index b28a4d0a3150..066a2b9d2b3c 100644
--- a/drivers/net/virtio/virtio_net.h
+++ b/drivers/net/virtio/virtio_net.h
@@ -115,9 +115,6 @@ struct virtnet_rq {
 
 	/* Record the last dma info to free after new pages is allocated. */
 	struct virtnet_rq_dma *last_dma;
-
-	/* Do dma by self */
-	bool do_dma;
 };
 
 struct virtnet_info {
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 2c5089d3b510..9092bcdebb53 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2905,6 +2905,28 @@ int virtqueue_set_dma_premapped(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_set_dma_premapped);
 
+/**
+ * virtqueue_get_dma_premapped - get the vring premapped mode
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * Get the premapped mode of the vq.
+ *
+ * Returns bool for the vq premapped mode.
+ */
+bool virtqueue_get_dma_premapped(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	bool premapped;
+
+	START_USE(vq);
+	premapped = vq->premapped;
+	END_USE(vq);
+
+	return premapped;
+
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_dma_premapped);
+
 /**
  * virtqueue_reset - detach and recycle all unused buffers
  * @_vq: the struct virtqueue we're talking about.
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 2596f0e7e395..3e9a2bb75af6 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -98,6 +98,7 @@ bool virtqueue_enable_cb(struct virtqueue *vq);
 unsigned virtqueue_enable_cb_prepare(struct virtqueue *vq);
 
 int virtqueue_set_dma_premapped(struct virtqueue *_vq);
+bool virtqueue_get_dma_premapped(struct virtqueue *_vq);
 
 bool virtqueue_poll(struct virtqueue *vq, unsigned);
 
-- 
2.32.0.3.g01195cf9f





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