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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Radoslaw Tyl <radoslawx.tyl@intel.com>,
        Andrew Bowers <andrewx.bowers@intel.com>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 080/220] ixgbe: Fix ixgbe TX hangs with XDP_TX beyond queue limit
Date:   Fri, 22 Nov 2019 11:27:25 +0100
Message-Id: <20191122100918.149260395@linuxfoundation.org>
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From: Radoslaw Tyl <radoslawx.tyl@intel.com>

[ Upstream commit 8d7179b1e2d64b3493c0114916486fe92e6109a9 ]

We have Tx hang when number Tx and XDP queues are more than 64.
In XDP always is MTQC == 0x0 (64TxQs). We need more space for Tx queues.

Signed-off-by: Radoslaw Tyl <radoslawx.tyl@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 85280765d793d..f3e21de3b1f0b 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -3582,12 +3582,18 @@ static void ixgbe_setup_mtqc(struct ixgbe_adapter *adapter)
 		else
 			mtqc |= IXGBE_MTQC_64VF;
 	} else {
-		if (tcs > 4)
+		if (tcs > 4) {
 			mtqc = IXGBE_MTQC_RT_ENA | IXGBE_MTQC_8TC_8TQ;
-		else if (tcs > 1)
+		} else if (tcs > 1) {
 			mtqc = IXGBE_MTQC_RT_ENA | IXGBE_MTQC_4TC_4TQ;
-		else
-			mtqc = IXGBE_MTQC_64Q_1PB;
+		} else {
+			u8 max_txq = adapter->num_tx_queues +
+				adapter->num_xdp_queues;
+			if (max_txq > 63)
+				mtqc = IXGBE_MTQC_RT_ENA | IXGBE_MTQC_4TC_4TQ;
+			else
+				mtqc = IXGBE_MTQC_64Q_1PB;
+		}
 	}
 
 	IXGBE_WRITE_REG(hw, IXGBE_MTQC, mtqc);
-- 
2.20.1