On 09/06/2018 08:19 PM, Jens Freimann wrote:
Add helper functions to set/clear and check descriptor flags.
Signed-off-by: Jens Freimann <jfreim...@redhat.com>
---
drivers/net/virtio/virtio_ring.h | 26 ++++++++++++++++++++++++++
drivers/net/virtio/virtqueue.h | 19 +++++++++++++++++++
2 files changed, 45 insertions(+)
diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h
index e2c597434..f3b23f419 100644
--- a/drivers/net/virtio/virtio_ring.h
+++ b/drivers/net/virtio/virtio_ring.h
@@ -78,6 +78,8 @@ struct vring_packed_desc_event {
struct vring {
unsigned int num;
+ unsigned int avail_wrap_counter;
+ unsigned int used_wrap_counter;
union {
struct vring_desc_packed *desc_packed;
struct vring_desc *desc;
@@ -92,6 +94,30 @@ struct vring {
};
};
+static inline void
+_set_desc_avail(struct vring_desc_packed *desc, int wrap_counter)
+{
+ desc->flags |= VRING_DESC_F_AVAIL(wrap_counter) |
+ VRING_DESC_F_USED(!wrap_counter);
It implies the avail and used bits to be cleared beforehand.
Maybe it would be safer to clear them in the helper?
+}
+
+static inline void
+set_desc_avail(struct vring *vr, struct vring_desc_packed *desc)
+{
+ _set_desc_avail(desc, vr->avail_wrap_counter);
+}
+
+static inline int
+desc_is_used(struct vring_desc_packed *desc, struct vring *vr)
+{
+ uint16_t used, avail;
+
+ used = !!(desc->flags & VRING_DESC_F_USED(1));
+ avail = !!(desc->flags & VRING_DESC_F_AVAIL(1));
+
+ return used == avail && used == vr->used_wrap_counter;
+}
+
/* The standard layout for the ring is a continuous chunk of memory which
* looks like this. We assume num is a power of 2.
*
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index d2a0b651a..53fce61b4 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -245,6 +245,25 @@ struct virtio_tx_region {
__attribute__((__aligned__(16)));
};
+static inline uint16_t
+increment_pq_index(uint16_t idx, size_t ring_size)
+{
+ return ++idx >= ring_size ? 0 : idx;
+}
Not sure this helper is really useful, as it ends up
doing two checks in a row.
+
+static inline uint16_t
+update_pq_avail_index(struct virtqueue *vq)
+{
+ uint16_t idx;
+
+ idx = increment_pq_index(vq->vq_avail_idx, vq->vq_nentries);
+ if (idx == 0)
+ vq->vq_ring.avail_wrap_counter ^= 1;
+ vq->vq_avail_idx = idx;
+
+ return vq->vq_avail_idx;
+}
So it could be simplified to:
{
if (++vq->vq_avail_idx >= vq->vq_entries) {
vq->vq_avail_idx = 0;
vq->vq_ring.avail_wrap_counter ^= 1;
}
return vq->vq_avail_idx;
}
+
static inline void
vring_desc_init_packed(struct vring *vr, int n)
{
