On Tue, Mar 19, 2019 at 02:28:30PM +0100, Maxime Coquelin wrote:
On 3/19/19 11:09 AM, Tiwei Bie wrote:
On Tue, Mar 19, 2019 at 10:44:32AM +0100, Jens Freimann wrote:
On Tue, Mar 19, 2019 at 02:43:07PM +0800, Tiwei Bie wrote:
Put split ring and packed ring specific fields into separate
sub-structures, and also union them as they won't be available
at the same time.
Signed-off-by: Tiwei Bie <tiwei....@intel.com>
---
drivers/net/virtio/virtio_ethdev.c | 71 +++++++++---------
drivers/net/virtio/virtio_rxtx.c | 66 ++++++++---------
drivers/net/virtio/virtio_rxtx_simple.h | 2 +-
drivers/net/virtio/virtio_rxtx_simple_neon.c | 2 +-
drivers/net/virtio/virtio_rxtx_simple_sse.c | 2 +-
drivers/net/virtio/virtqueue.c | 6 +-
drivers/net/virtio/virtqueue.h | 77 +++++++++++---------
7 files changed, 117 insertions(+), 109 deletions(-)
[snip]
...
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 80c0c43c3..48b3912e6 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -191,17 +191,22 @@ struct vq_desc_extra {
struct virtqueue {
struct virtio_hw *hw; /**< virtio_hw structure pointer. */
- struct vring vq_ring; /**< vring keeping desc, used and avail */
- struct vring_packed ring_packed; /**< vring keeping descs */
- bool used_wrap_counter;
- uint16_t cached_flags; /**< cached flags for descs */
- uint16_t event_flags_shadow;
+ union {
+ struct {
+ /**< vring keeping desc, used and avail */
+ struct vring ring;
+ } vq_split;
- /**
- * Last consumed descriptor in the used table,
- * trails vq_ring.used->idx.
- */
- uint16_t vq_used_cons_idx;
+ struct {
+ /**< vring keeping descs and events */
+ struct vring_packed ring;
+ bool used_wrap_counter;
+ uint16_t cached_flags; /**< cached flags for descs */
+ uint16_t event_flags_shadow;
+ } vq_packed;
+ };
+
+ uint16_t vq_used_cons_idx; /**< last consumed descriptor */
uint16_t vq_nentries; /**< vring desc numbers */
uint16_t vq_free_cnt; /**< num of desc available */
uint16_t vq_avail_idx; /**< sync until needed */
Honest question: What do we really gain by putting it in a union? We
save a little memory. But we also make code less readable IMHO.
I think it will make it clear that fields like used_wrap_counter
are only available in packed ring which will make the code more
readable.
If we do this, can we at least shorten some variable names, like drop
the vq_ prefix? (It's used everywhere like vq->vq_packed*, so with
vq->packed* we don't loose any context).
I prefer to have consistent prefix like most fields in this
structure (although some fields don't really follow this).
As Jens, I tend to agree that the vq_ prefix is quite redundant.
However, I think it is better to keep it in this patch for consistency.
Maybe it can be remove in a separate patch later?
I thought it might be convenient to change it now as we are touching
all related code anyway. But I also don't want to block the patch because of
this cosmetic thing. So let's defer it to a later patch set.
regards,
Jens
