[dpdk-stable] patch 'net/virtio: fix in-order Tx path for split ring' has been queued to LTS release 18.11.2

[Kevin Traynor <ktraynor@redhat.com>]

Hi,

FYI, your patch has been queued to LTS release 18.11.2

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 04/16/19. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Thanks.

Kevin Traynor

---
From 8cc891643229266c99063c1da606e6438ac9d9bd Mon Sep 17 00:00:00 2001
From: Tiwei Bie <tiwei.bie@intel.com>
Date: Tue, 19 Feb 2019 18:59:48 +0800
Subject: [PATCH] net/virtio: fix in-order Tx path for split ring

[ upstream commit e788032aaca7193a107ca3fcfb71b0f0ba6c3db5 ]

When IN_ORDER feature is negotiated, device may just write out a
single used ring entry for a batch of buffers:

"""
Some devices always use descriptors in the same order in which they
have been made available. These devices can offer the VIRTIO_F_IN_ORDER
feature. If negotiated, this knowledge allows devices to notify the
use of a batch of buffers to the driver by only writing out a single
used ring entry with the id corresponding to the head entry of the
descriptor chain describing the last buffer in the batch.

The device then skips forward in the ring according to the size of
the batch. Accordingly, it increments the used idx by the size of
the batch.

The driver needs to look up the used id and calculate the batch size
to be able to advance to where the next used ring entry will be written
by the device.
"""

Currently, the in-order Tx path in split ring can't handle this.
With this patch, driver will allocate desc_extra[] based on the
index in avail/used ring instead of the index in descriptor table.
And driver can just relay on the used->idx written by device to
reclaim the descriptors and Tx buffers.

Fixes: e5f456a98d3c ("net/virtio: support in-order Rx and Tx")

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 drivers/net/virtio/virtio_rxtx.c | 28 ++++++++++------------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index eb891433e..7e035130f 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -193,5 +193,5 @@ static void
 virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
 {
-	uint16_t i, used_idx, desc_idx = 0, last_idx;
+	uint16_t i, idx = vq->vq_used_cons_idx;
 	int16_t free_cnt = 0;
 	struct vq_desc_extra *dxp = NULL;
@@ -201,13 +201,6 @@ virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
 
 	for (i = 0; i < num; i++) {
-		struct vring_used_elem *uep;
-
-		used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
-		uep = &vq->vq_ring.used->ring[used_idx];
-		desc_idx = (uint16_t)uep->id;
-
-		dxp = &vq->vq_descx[desc_idx];
-		vq->vq_used_cons_idx++;
-
+		dxp = &vq->vq_descx[idx++ & (vq->vq_nentries - 1)];
+		free_cnt += dxp->ndescs;
 		if (dxp->cookie != NULL) {
 			rte_pktmbuf_free(dxp->cookie);
@@ -216,10 +209,6 @@ virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
 	}
 
-	last_idx = desc_idx + dxp->ndescs - 1;
-	free_cnt = last_idx - vq->vq_desc_tail_idx;
-	if (free_cnt <= 0)
-		free_cnt += vq->vq_nentries;
-
-	vq_ring_free_inorder(vq, last_idx, free_cnt);
+	vq->vq_free_cnt += free_cnt;
+	vq->vq_used_cons_idx = idx;
 }
 
@@ -422,5 +411,5 @@ virtqueue_enqueue_xmit_inorder(struct virtnet_tx *txvq,
 	while (i < num) {
 		idx = idx & (vq->vq_nentries - 1);
-		dxp = &vq->vq_descx[idx];
+		dxp = &vq->vq_descx[vq->vq_avail_idx & (vq->vq_nentries - 1)];
 		dxp->cookie = (void *)cookies[i];
 		dxp->ndescs = 1;
@@ -473,5 +462,8 @@ virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
 	head_idx = vq->vq_desc_head_idx;
 	idx = head_idx;
-	dxp = &vq->vq_descx[idx];
+	if (in_order)
+		dxp = &vq->vq_descx[vq->vq_avail_idx & (vq->vq_nentries - 1)];
+	else
+		dxp = &vq->vq_descx[idx];
 	dxp->cookie = (void *)cookie;
 	dxp->ndescs = needed;
-- 
2.20.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2019-04-10 14:06:09.565312586 +0100
+++ 0020-net-virtio-fix-in-order-Tx-path-for-split-ring.patch	2019-04-10 14:06:07.837294862 +0100
@@ -1,8 +1,10 @@
-From e788032aaca7193a107ca3fcfb71b0f0ba6c3db5 Mon Sep 17 00:00:00 2001
+From 8cc891643229266c99063c1da606e6438ac9d9bd Mon Sep 17 00:00:00 2001
 From: Tiwei Bie <tiwei.bie@intel.com>
 Date: Tue, 19 Feb 2019 18:59:48 +0800
 Subject: [PATCH] net/virtio: fix in-order Tx path for split ring
 
+[ upstream commit e788032aaca7193a107ca3fcfb71b0f0ba6c3db5 ]
+
 When IN_ORDER feature is negotiated, device may just write out a
 single used ring entry for a batch of buffers:
 
@@ -30,7 +32,6 @@
 reclaim the descriptors and Tx buffers.
 
 Fixes: e5f456a98d3c ("net/virtio: support in-order Rx and Tx")
-Cc: stable@dpdk.org
 
 Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
 Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
@@ -39,17 +40,17 @@
  1 file changed, 10 insertions(+), 18 deletions(-)
 
 diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
-index b07ceac6d..407f58bce 100644
+index eb891433e..7e035130f 100644
 --- a/drivers/net/virtio/virtio_rxtx.c
 +++ b/drivers/net/virtio/virtio_rxtx.c
-@@ -280,5 +280,5 @@ static void
+@@ -193,5 +193,5 @@ static void
  virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
  {
 -	uint16_t i, used_idx, desc_idx = 0, last_idx;
 +	uint16_t i, idx = vq->vq_used_cons_idx;
  	int16_t free_cnt = 0;
  	struct vq_desc_extra *dxp = NULL;
-@@ -288,13 +288,6 @@ virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
+@@ -201,13 +201,6 @@ virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
  
  	for (i = 0; i < num; i++) {
 -		struct vring_used_elem *uep;
@@ -65,7 +66,7 @@
 +		free_cnt += dxp->ndescs;
  		if (dxp->cookie != NULL) {
  			rte_pktmbuf_free(dxp->cookie);
-@@ -303,10 +296,6 @@ virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
+@@ -216,10 +209,6 @@ virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
  	}
  
 -	last_idx = desc_idx + dxp->ndescs - 1;
@@ -78,14 +79,14 @@
 +	vq->vq_used_cons_idx = idx;
  }
  
-@@ -557,5 +546,5 @@ virtqueue_enqueue_xmit_inorder(struct virtnet_tx *txvq,
+@@ -422,5 +411,5 @@ virtqueue_enqueue_xmit_inorder(struct virtnet_tx *txvq,
  	while (i < num) {
  		idx = idx & (vq->vq_nentries - 1);
 -		dxp = &vq->vq_descx[idx];
 +		dxp = &vq->vq_descx[vq->vq_avail_idx & (vq->vq_nentries - 1)];
  		dxp->cookie = (void *)cookies[i];
  		dxp->ndescs = 1;
-@@ -709,5 +698,8 @@ virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
+@@ -473,5 +462,8 @@ virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
  	head_idx = vq->vq_desc_head_idx;
  	idx = head_idx;
 -	dxp = &vq->vq_descx[idx];