[dpdk-stable] patch 'net/mlx5: fix Rx queue count calculation' has been queued to stable release 19.11.6

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 19.11.6

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 11/26/20. 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.

Queued patches are on a temporary branch at:
https://github.com/bluca/dpdk-stable

This queued commit can be viewed at:
https://github.com/bluca/dpdk-stable/commit/0134408f53261d7dca1d7f37d47925e7bcf6f87f

Thanks.

Luca Boccassi

---
>From 0134408f53261d7dca1d7f37d47925e7bcf6f87f Mon Sep 17 00:00:00 2001
From: Maxime Leroy <maxime.leroy at 6wind.com>
Date: Tue, 17 Nov 2020 12:26:46 +0100
Subject: [PATCH] net/mlx5: fix Rx queue count calculation

[ upstream commit 9ae9720d7f0c12f877df9214f7cbedae546d4020 ]

The commit d2d57605522d ("net/mlx5: fix Rx queue count calculation") is
incorrect because the count calculation is wrong for the next cqe:

Example:

 Compressed Set of packets 1  |   Compressed Set of packets 2
C | a | e0 | e1 | e2 | e3 | e4 | e5 | C | a | e0

There are 2 compressed set of packets in the first queue. For the first
set, n is computed correctly.

But for the second, n is not computed properly. Because the zip context
is for the first set. The  second set is not yet decompressed, so
there are no context.

To fix the issue, we should only use the zip context for the first CQEs
series.

Fixes: d2d57605522d ("net/mlx5: fix Rx queue count calculation")

Signed-off-by: Maxime Leroy <maxime.leroy at 6wind.com>
Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro at 6wind.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo at nvidia.com>
---
 drivers/net/mlx5/mlx5_rxtx.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 9f4a04122c..6e5605d37e 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -468,11 +468,18 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
 {
 	struct rxq_zip *zip = &rxq->zip;
 	volatile struct mlx5_cqe *cqe;
-	unsigned int cq_ci = rxq->cq_ci;
 	const unsigned int cqe_n = (1 << rxq->cqe_n);
 	const unsigned int cqe_cnt = cqe_n - 1;
-	unsigned int used = 0;
+	unsigned int cq_ci, used;
 
+	/* if we are processing a compressed cqe */
+	if (zip->ai) {
+		used = zip->cqe_cnt - zip->ai;
+		cq_ci = zip->cq_ci;
+	} else {
+		used = 0;
+		cq_ci = rxq->cq_ci;
+	}
 	cqe = &(*rxq->cqes)[cq_ci & cqe_cnt];
 	while (check_cqe(cqe, cqe_n, cq_ci) != MLX5_CQE_STATUS_HW_OWN) {
 		int8_t op_own;
@@ -480,10 +487,7 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
 
 		op_own = cqe->op_own;
 		if (MLX5_CQE_FORMAT(op_own) == MLX5_COMPRESSED)
-			if (unlikely(zip->ai))
-				n = zip->cqe_cnt - zip->ai;
-			else
-				n = rte_be_to_cpu_32(cqe->byte_cnt);
+			n = rte_be_to_cpu_32(cqe->byte_cnt);
 		else
 			n = 1;
 		cq_ci += n;
-- 
2.27.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2020-11-24 16:50:36.717569005 +0000
+++ 0004-net-mlx5-fix-Rx-queue-count-calculation.patch	2020-11-24 16:50:36.549495892 +0000
@@ -1 +1 @@
-From 9ae9720d7f0c12f877df9214f7cbedae546d4020 Mon Sep 17 00:00:00 2001
+From 0134408f53261d7dca1d7f37d47925e7bcf6f87f Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 9ae9720d7f0c12f877df9214f7cbedae546d4020 ]
+
@@ -25 +26,0 @@
-Cc: stable at dpdk.org
@@ -35 +36 @@
-index 844a1c633d..2733dcd3ff 100644
+index 9f4a04122c..6e5605d37e 100644
@@ -38 +39 @@
-@@ -462,11 +462,18 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
+@@ -468,11 +468,18 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
@@ -59 +60 @@
-@@ -474,10 +481,7 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
+@@ -480,10 +487,7 @@ rx_queue_count(struct mlx5_rxq_data *rxq)