linux-kernel - [PATCH 4.4 014/192] [PATCH 014/135] ixgbe: Fix handling of NAPI budget when multiple queues are enabled per vector

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Date:   Mon, 12 Sep 2016 18:58:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexander Duyck <aduyck@...antis.com>,
        Darin Miller <darin.j.miller@...el.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 014/192] [PATCH 014/135] ixgbe: Fix handling of NAPI budget when multiple queues are enabled per vector

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 5d6002b7b822c7423e75d4651e6790bfb5642b1b ]

This patch corrects an issue in which the polling routine would increase
the budget for Rx to at least 1 per queue if multiple queues were present.
This would result in Rx packets being processed when the budget was 0 which
is meant to indicate that no Rx can be handled.

Signed-off-by: Alexander Duyck <aduyck@...antis.com>
Tested-by: Darin Miller <darin.j.miller@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -2786,7 +2786,8 @@ int ixgbe_poll(struct napi_struct *napi,
 	ixgbe_for_each_ring(ring, q_vector->tx)
 		clean_complete &= !!ixgbe_clean_tx_irq(q_vector, ring);
 
-	if (!ixgbe_qv_lock_napi(q_vector))
+	/* Exit if we are called by netpoll or busy polling is active */
+	if ((budget <= 0) || !ixgbe_qv_lock_napi(q_vector))
 		return budget;
 
 	/* attempt to distribute budget to each queue fairly, but don't allow