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Subject[RFC PATCH 04/16] virtio_ring: split: extract detach_from_vring_split()
Date
To handle freeing buf from the detached vring, do a split for
detach_buf_split().

The split function detach_buf_from_vring_split() is used to release buf
from vring, and the vq passed in is read-only. All modifications are for
vring.

In this way, detach_buf_from_vring_split() becomes a general function,
which can be used for detach_buf_split() and also for handling detached
vrings.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 54 +++++++++++++++++++++++-------------
1 file changed, 34 insertions(+), 20 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 6fd45c9a3517..aa85058978cb 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -734,54 +734,68 @@ static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
return needs_kick;
}

-static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
- void **ctx)
+static int detach_buf_from_vring_split(struct vring_virtqueue_split *vring,
+ struct vring_virtqueue const *vq,
+ unsigned int head,
+ unsigned int free_head,
+ void **ctx)
{
- unsigned int i, j;
+ unsigned int i, j, num = 0;
__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);

/* Clear data ptr. */
- vq->split.desc_state[head].data = NULL;
+ vring->desc_state[head].data = NULL;

/* Put back on free list: unmap first-level descriptors and find end */
i = head;

- while (vq->split.vring.desc[i].flags & nextflag) {
- vring_unmap_one_split(vq, &vq->split.desc_extra[i]);
- i = vq->split.desc_extra[i].next;
- vq->vq.num_free++;
+ while (vring->vring.desc[i].flags & nextflag) {
+ vring_unmap_one_split(vq, &vring->desc_extra[i]);
+ i = vring->desc_extra[i].next;
+ ++num;
}

- vring_unmap_one_split(vq, &vq->split.desc_extra[i]);
- vq->split.desc_extra[i].next = vq->free_head;
- vq->free_head = head;
+ vring_unmap_one_split(vq, &vring->desc_extra[i]);
+ vring->desc_extra[i].next = free_head;

- /* Plus final descriptor */
- vq->vq.num_free++;
+ ++num;

if (vq->indirect) {
struct vring_desc *indir_desc =
- vq->split.desc_state[head].indir_desc;
+ vring->desc_state[head].indir_desc;
u32 len;

/* Free the indirect table, if any, now that it's unmapped. */
if (!indir_desc)
- return;
+ return num;

- len = vq->split.desc_extra[head].len;
+ len = vring->desc_extra[head].len;

- BUG_ON(!(vq->split.desc_extra[head].flags &
- VRING_DESC_F_INDIRECT));
+ BUG_ON(!(vring->desc_extra[head].flags & VRING_DESC_F_INDIRECT));
BUG_ON(len == 0 || len % sizeof(struct vring_desc));

for (j = 0; j < len / sizeof(struct vring_desc); j++)
vring_unmap_one_split_indirect(vq, &indir_desc[j]);

kfree(indir_desc);
- vq->split.desc_state[head].indir_desc = NULL;
+ vring->desc_state[head].indir_desc = NULL;
} else if (ctx) {
- *ctx = vq->split.desc_state[head].indir_desc;
+ *ctx = vring->desc_state[head].indir_desc;
}
+
+ return num;
+}
+
+static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
+ void **ctx)
+{
+ int num;
+
+ num = detach_buf_from_vring_split(&vq->split, vq, head, vq->free_head,
+ ctx);
+
+ vq->vq.num_free += num;
+ vq->free_head = head;
}

static inline bool more_used_split(const struct vring_virtqueue *vq)
--
2.31.0
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