[PATCH net-next v2 01/13] virtio_ring: introduce vring_need_unmap_buffer

Xuan Zhuo
2024-10-30T08:25:02Z

To make the code readable, introduce vring_need_unmap_buffer() to
replace do_unmap.

use_dma_api premapped -> vring_need_unmap_buffer()
1. false false false
2. true false true
3. true true false

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
---
drivers/virtio/virtio_ring.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 98374ed7c577..97590c201aa2 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -175,11 +175,6 @@ struct vring_virtqueue {
/* Do DMA mapping by driver */
bool premapped;

- /* Do unmap or not for desc. Just when premapped is False and
- * use_dma_api is true, this is true.
- */
- bool do_unmap;
-
/* Head of free buffer list. */
unsigned int free_head;
/* Number we've added since last sync. */
@@ -297,6 +292,11 @@ static bool vring_use_dma_api(const struct virtio_device *vdev)
return false;
}

+static bool vring_need_unmap_buffer(const struct vring_virtqueue *vring)
+{
+ return vring->use_dma_api && !vring->premapped;
+}
+
size_t virtio_max_dma_size(const struct virtio_device *vdev)
{
size_t max_segment_size = SIZE_MAX;
@@ -445,7 +445,7 @@ static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq,
{
u16 flags;

- if (!vq->do_unmap)
+ if (!vring_need_unmap_buffer(vq))
return;

flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
@@ -475,7 +475,7 @@ static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
- if (!vq->do_unmap)
+ if (!vring_need_unmap_buffer(vq))
goto out;

dma_unmap_page(vring_dma_dev(vq),
@@ -643,7 +643,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
}
/* Last one doesn't continue. */
desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
- if (!indirect && vq->do_unmap)
+ if (!indirect && vring_need_unmap_buffer(vq))
vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &=
~VRING_DESC_F_NEXT;

@@ -802,7 +802,7 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
VRING_DESC_F_INDIRECT));
BUG_ON(len == 0 || len % sizeof(struct vring_desc));

- if (vq->do_unmap) {
+ if (vring_need_unmap_buffer(vq)) {
for (j = 0; j < len / sizeof(struct vring_desc); j++)
vring_unmap_one_split_indirect(vq, &indir_desc[j]);
}
@@ -1236,7 +1236,7 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
- if (!vq->do_unmap)
+ if (!vring_need_unmap_buffer(vq))
return;

dma_unmap_page(vring_dma_dev(vq),
@@ -1251,7 +1251,7 @@ static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
{
u16 flags;

- if (!vq->do_unmap)
+ if (!vring_need_unmap_buffer(vq))
return;

flags = le16_to_cpu(desc->flags);
@@ -1632,7 +1632,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
if (!desc)
return;

- if (vq->do_unmap) {
+ if (vring_need_unmap_buffer(vq)) {
len = vq->packed.desc_extra[id].len;
for (i = 0; i < len / sizeof(struct vring_packed_desc);
i++)
@@ -2091,7 +2091,6 @@ static struct virtqueue *vring_create_virtqueue_packed(
vq->dma_dev = dma_dev;
vq->use_dma_api = vring_use_dma_api(vdev);
vq->premapped = false;
- vq->do_unmap = vq->use_dma_api;

vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
!context;
@@ -2636,7 +2635,6 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index,
vq->dma_dev = dma_dev;
vq->use_dma_api = vring_use_dma_api(vdev);
vq->premapped = false;
- vq->do_unmap = vq->use_dma_api;

vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
!context;
@@ -2799,7 +2797,6 @@ int virtqueue_set_dma_premapped(struct virtqueue *_vq)
}

vq->premapped = true;
- vq->do_unmap = false;

END_USE(vq);

--
2.32.0.3.g01195cf9f