From: Maxime Chevallier <maxime.chevallier@bootlin.com>
Date: Thu, 12 Jul 2018 13:54:22 +0200
Subject: net: mvpp2: make sure we don't spread load on disabled CPUs
Patch-mainline: v4.19-rc1
Git-commit: 2a2f467daf96f519f9d2ec69e133ad1365d3e8ff
References: bsc#1119113 FATE#326472

When filling the RSS table, we have to make sure that the rx queue is
attached to an online CPU.

This patch is not a full support for cpu_hotplug, but rather a way to
make sure that we don't break network on system booted with the maxcpus
parameter.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c
@@ -109,11 +109,17 @@ void mvpp2_cls_oversize_rxq_set(struct m
 
 static inline u32 mvpp22_rxfh_indir(struct mvpp2_port *port, u32 rxq)
 {
-	int nrxqs, cpus = num_possible_cpus();
+	int nrxqs, cpu, cpus = num_possible_cpus();
 
 	/* Number of RXQs per CPU */
 	nrxqs = port->nrxqs / cpus;
 
+	/* CPU that will handle this rx queue */
+	cpu = rxq / nrxqs;
+
+	if (!cpu_online(cpu))
+		return port->first_rxq;
+
 	/* Indirection to better distribute the paquets on the CPUs when
 	 * configuring the RSS queues.
 	 */