linux-kernel - [PATCH 4.4 020/192] [PATCH 020/135] fm10k: Fix handling of NAPI budget when multiple queues are enabled per vector

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Date:   Mon, 12 Sep 2016 18:58:49 +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>,
        Krishneil Singh <Krishneil.k.singh@...el.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 020/192] [PATCH 020/135] fm10k: 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 9f872986479b6e0543eb5c615e5f9491bb04e5c1 ]

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: Krishneil Singh <Krishneil.k.singh@...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/fm10k/fm10k_main.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c
@@ -1428,6 +1428,10 @@ static int fm10k_poll(struct napi_struct
 	fm10k_for_each_ring(ring, q_vector->tx)
 		clean_complete &= fm10k_clean_tx_irq(q_vector, ring);
 
+	/* Handle case where we are called by netpoll with a budget of 0 */
+	if (budget <= 0)
+		return budget;
+
 	/* attempt to distribute budget to each queue fairly, but don't
 	 * allow the budget to go below 1 because we'll exit polling
 	 */