patch 'net/mlx5: relax headroom assertion' has been queued to stable release 20.11.5

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 20.11.5

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 02/20/22. 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/66aa6f946717b3391a7aafe04a9909f4f248a465

Thanks.

Luca Boccassi

---
>From 66aa6f946717b3391a7aafe04a9909f4f248a465 Mon Sep 17 00:00:00 2001
From: Dmitry Kozlyuk <dkozlyuk at nvidia.com>
Date: Tue, 28 Dec 2021 11:20:43 +0200
Subject: [PATCH] net/mlx5: relax headroom assertion

[ upstream commit 637582afcc886fc53c1dc7a3686cc771abad2cfd ]

A debug assertion in Single-Packet Receive Queue (SPRQ) mode
required all Rx mbufs to have a 128 byte headroom,
based on the assumption that rte_pktmbuf_init() sets it.
However, rte_pktmbuf_init() may set a smaller headroom
if the dataroom is insufficient, e.g. this is a natural case
for split buffer segments. The headroom can also be larger.
Only check the headroom size when vectored Rx routines
are used because they rely on it. Relax the assertion
to require sufficient headroom size, not an exact one.

Fixes: a0a45e8af723 ("net/mlx5: configure Rx queue for buffer split")

Signed-off-by: Dmitry Kozlyuk <dkozlyuk at nvidia.com>
Acked-by: Matan Azrad <matan at nvidia.com>
---
 drivers/net/mlx5/mlx5_rxq.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index e4dfb82822..d7e5d194e3 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -207,6 +207,7 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
 	unsigned int elts_n = mlx5_rxq_mprq_enabled(&rxq_ctrl->rxq) ?
 		(1 << rxq_ctrl->rxq.elts_n) * (1 << rxq_ctrl->rxq.strd_num_n) :
 		(1 << rxq_ctrl->rxq.elts_n);
+	bool has_vec_support = mlx5_rxq_check_vec_support(&rxq_ctrl->rxq) > 0;
 	unsigned int i;
 	int err;
 
@@ -222,8 +223,9 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
 			rte_errno = ENOMEM;
 			goto error;
 		}
-		/* Headroom is reserved by rte_pktmbuf_alloc(). */
-		MLX5_ASSERT(DATA_OFF(buf) == RTE_PKTMBUF_HEADROOM);
+		/* Only vectored Rx routines rely on headroom size. */
+		MLX5_ASSERT(!has_vec_support ||
+			    DATA_OFF(buf) >= RTE_PKTMBUF_HEADROOM);
 		/* Buffer is supposed to be empty. */
 		MLX5_ASSERT(rte_pktmbuf_data_len(buf) == 0);
 		MLX5_ASSERT(rte_pktmbuf_pkt_len(buf) == 0);
@@ -236,7 +238,7 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
 		(*rxq_ctrl->rxq.elts)[i] = buf;
 	}
 	/* If Rx vector is activated. */
-	if (mlx5_rxq_check_vec_support(&rxq_ctrl->rxq) > 0) {
+	if (has_vec_support) {
 		struct mlx5_rxq_data *rxq = &rxq_ctrl->rxq;
 		struct rte_mbuf *mbuf_init = &rxq->fake_mbuf;
 		struct rte_pktmbuf_pool_private *priv =
-- 
2.30.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2022-02-18 12:37:38.972455641 +0000
+++ 0021-net-mlx5-relax-headroom-assertion.patch	2022-02-18 12:37:37.558788972 +0000
@@ -1 +1 @@
-From 637582afcc886fc53c1dc7a3686cc771abad2cfd Mon Sep 17 00:00:00 2001
+From 66aa6f946717b3391a7aafe04a9909f4f248a465 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 637582afcc886fc53c1dc7a3686cc771abad2cfd ]
+
@@ -17 +18,0 @@
-Cc: stable at dpdk.org
@@ -26 +27 @@
-index eda609dd78..ee07c610b9 100644
+index e4dfb82822..d7e5d194e3 100644
@@ -29,4 +30,4 @@
-@@ -140,6 +140,7 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
- 			      RTE_BIT32(rxq_ctrl->rxq.elts_n) *
- 			      RTE_BIT32(rxq_ctrl->rxq.log_strd_num) :
- 			      RTE_BIT32(rxq_ctrl->rxq.elts_n);
+@@ -207,6 +207,7 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
+ 	unsigned int elts_n = mlx5_rxq_mprq_enabled(&rxq_ctrl->rxq) ?
+ 		(1 << rxq_ctrl->rxq.elts_n) * (1 << rxq_ctrl->rxq.strd_num_n) :
+ 		(1 << rxq_ctrl->rxq.elts_n);
@@ -37 +38 @@
-@@ -161,8 +162,9 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
+@@ -222,8 +223,9 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
@@ -49 +50 @@
-@@ -175,7 +177,7 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)
+@@ -236,7 +238,7 @@ rxq_alloc_elts_sprq(struct mlx5_rxq_ctrl *rxq_ctrl)