netdev - [PATCH net 1/2] i40e: Fix ATR queue selection

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Message-Id: <20210818174217.4138922-2-anthony.l.nguyen@intel.com>
Date:   Wed, 18 Aug 2021 10:42:16 -0700
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
        netdev@...r.kernel.org, anthony.l.nguyen@...el.com,
        sassmann@...hat.com,
        Przemyslaw Patynowski <przemyslawx.patynowski@...el.com>,
        Dave Switzer <david.switzer@...el.com>
Subject: [PATCH net 1/2] i40e: Fix ATR queue selection

From: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>

Without this patch, ATR does not work. Receive/transmit uses queue
selection based on SW DCB hashing method.

If traffic classes are not configured for PF, then use
netdev_pick_tx function for selecting queue for packet transmission.
Instead of calling i40e_swdcb_skb_tx_hash, call netdev_pick_tx,
which ensures that packet is transmitted/received from CPU that is
running the application.

Reproduction steps:
1. Load i40e driver
2. Map each MSI interrupt of i40e port for each CPU
3. Disable ntuple, enable ATR i.e.:
ethtool -K $interface ntuple off
ethtool --set-priv-flags $interface flow-director-atr
4. Run application that is generating traffic and is bound to a
single CPU, i.e.:
taskset -c 9 netperf -H 1.1.1.1 -t TCP_RR -l 10
5. Observe behavior:
Application's traffic should be restricted to the CPU provided in
taskset.

Fixes: 821bd0c990ba ("i40e: Fix queue-to-TC mapping on Tx")
Signed-off-by: Przemyslaw Patynowski <przemyslawx.patynowski@...el.com>
Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
Tested-by: Dave Switzer <david.switzer@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/i40e/i40e_txrx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 3f25bd8c4924..10a83e5385c7 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -3663,8 +3663,7 @@ u16 i40e_lan_select_queue(struct net_device *netdev,

 	/* is DCB enabled at all? */
 	if (vsi->tc_config.numtc == 1)
-		return i40e_swdcb_skb_tx_hash(netdev, skb,
-					      netdev->real_num_tx_queues);
+		return netdev_pick_tx(netdev, skb, sb_dev);

 	prio = skb->priority;
 	hw = &vsi->back->hw;
-- 
2.26.2