linux-kernel - [PATCH 18/19] virtio_ring: factor out split indirect detaching logic

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Message-ID: <20250324060127.2358-6-jasowang@redhat.com>
Date: Mon, 24 Mar 2025 14:01:26 +0800
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com,
	jasowang@...hat.com
Cc: xuanzhuo@...ux.alibaba.com,
	eperezma@...hat.com,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH 18/19] virtio_ring: factor out split indirect detaching logic

Factor out the split indirect descriptor detaching logic in order to
make it be reused by the in order support.

Signed-off-by: Jason Wang <jasowang@...hat.com>
---
 drivers/virtio/virtio_ring.c | 63 ++++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 28 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a1a8cd931052..0fad8e8419c8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -765,11 +765,42 @@ static bool virtqueue_kick_prepare_split(struct vring_virtqueue *vq)
 	return needs_kick;
 }
 
+static void detach_indirect_split(struct vring_virtqueue *vq,
+				  unsigned int head)
+{
+	struct vring_desc_extra *extra = vq->split.desc_extra;
+	struct vring_desc *indir_desc =
+	       vq->split.desc_state[head].indir_desc;
+	unsigned int j;
+	u32 len, num;
+
+	/* Free the indirect table, if any, now that it's unmapped. */
+	if (!indir_desc)
+		return;
+	len = vq->split.desc_extra[head].len;
+
+	BUG_ON(!(vq->split.desc_extra[head].flags &
+			VRING_DESC_F_INDIRECT));
+	BUG_ON(len == 0 || len % sizeof(struct vring_desc));
+
+	num = len / sizeof(struct vring_desc);
+
+	extra = (struct vring_desc_extra *)&indir_desc[num];
+
+	if (vq->use_dma_api) {
+		for (j = 0; j < num; j++)
+			vring_unmap_one_split(vq, &extra[j]);
+	}
+
+	kfree(indir_desc);
+	vq->split.desc_state[head].indir_desc = NULL;
+}
+
 static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
 			     void **ctx)
 {
 	struct vring_desc_extra *extra;
-	unsigned int i, j;
+	unsigned int i;
 	__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
 
 	/* Clear data ptr. */
@@ -793,34 +824,10 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
 	/* Plus final descriptor */
 	vq->vq.num_free++;
 
-	if (vq->indirect) {
-		struct vring_desc *indir_desc =
-				vq->split.desc_state[head].indir_desc;
-		u32 len, num;
-
-		/* Free the indirect table, if any, now that it's unmapped. */
-		if (!indir_desc)
-			return;
-		len = vq->split.desc_extra[head].len;
-
-		BUG_ON(!(vq->split.desc_extra[head].flags &
-				VRING_DESC_F_INDIRECT));
-		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
-
-		num = len / sizeof(struct vring_desc);
-
-		extra = (struct vring_desc_extra *)&indir_desc[num];
-
-		if (vq->use_dma_api) {
-			for (j = 0; j < num; j++)
-				vring_unmap_one_split(vq, &extra[j]);
-		}
-
-		kfree(indir_desc);
-		vq->split.desc_state[head].indir_desc = NULL;
-	} else if (ctx) {
+	if (vq->indirect)
+		detach_indirect_split(vq, head);
+	else if (ctx)
 		*ctx = vq->split.desc_state[head].indir_desc;
-	}
 }
 
 static bool virtqueue_poll_split(const struct vring_virtqueue *vq,
-- 
2.42.0