netdev - [net PATCH] mlx5: fix bug reading rss_hash

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Date:   Mon, 22 May 2017 20:13:07 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Saeed Mahameed <saeedm@...lanox.com>
Cc:     Daniel Borkmann <borkmann@...earbox.net>, netdev@...r.kernel.org,
        Tariq Toukan <tariqt@...lanox.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Subject: [net PATCH] mlx5: fix bug reading rss_hash_type from CQE

Masks for extracting part of the Completion Queue Entry (CQE)
field rss_hash_type was swapped, namely CQE_RSS_HTYPE_IP and
CQE_RSS_HTYPE_L4.

The bug resulted in setting skb->l4_hash, even-though the
rss_hash_type indicated that hash was NOT computed over the
L4 (UDP or TCP) part of the packet.

Added comments from the datasheet, to make it more clear what
these masks are selecting.

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
 include/linux/mlx5/device.h |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/mlx5/device.h b/include/linux/mlx5/device.h
index dd9a263ed368..a940ec6a046c 100644
--- a/include/linux/mlx5/device.h
+++ b/include/linux/mlx5/device.h
@@ -787,8 +787,14 @@ enum {
 };
 
 enum {
-	CQE_RSS_HTYPE_IP	= 0x3 << 6,
-	CQE_RSS_HTYPE_L4	= 0x3 << 2,
+	CQE_RSS_HTYPE_IP	= 0x3 << 2,
+	/* cqe->rss_hash_type[3:2] - IP destination selected for hash
+	 * (00 = none,  01 = IPv4, 10 = IPv6, 11 = Reserved)
+	 */
+	CQE_RSS_HTYPE_L4	= 0x3 << 6,
+	/* cqe->rss_hash_type[7:6] - L4 destination selected for hash
+	 * (00 = none, 01 = TCP. 10 = UDP, 11 = IPSEC.SPI
+	 */
 };
 
 enum {