2017-04-17 06:43:54 +00:00
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From: Gregory CLEMENT <gregory.clement@free-electrons.com>
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Date: Thu, 4 Feb 2016 22:09:24 +0100
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Subject: [PATCH] net: mvneta: Fix the CPU choice in mvneta_percpu_elect
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When passing to the management of multiple RX queue, the
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mvneta_percpu_elect function was broken. The use of the modulo can lead
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to elect the wrong cpu. For example with rxq_def=2, if the CPU 2 goes
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offline and then online, we ended with the third RX queue activated in
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the same time on CPU 0 and CPU2, which lead to a kernel crash.
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With this fix, we don't try to get "the closer" CPU if the default CPU is
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gone, now we just use CPU 0 which always be there. Thanks to this, the
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code becomes more readable, easier to maintain and more predicable.
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Cc: stable@vger.kernel.org
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Fixes: 2dcf75e2793c ("net: mvneta: Associate RX queues with each CPU")
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Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/drivers/net/ethernet/marvell/mvneta.c
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+++ b/drivers/net/ethernet/marvell/mvneta.c
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2018-01-07 14:12:52 +00:00
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@@ -2851,9 +2851,14 @@ static void mvneta_percpu_disable(void *
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2017-04-17 06:43:54 +00:00
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static void mvneta_percpu_elect(struct mvneta_port *pp)
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{
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- int online_cpu_idx, max_cpu, cpu, i = 0;
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+ int elected_cpu = 0, max_cpu, cpu, i = 0;
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+
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+ /* Use the cpu associated to the rxq when it is online, in all
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+ * the other cases, use the cpu 0 which can't be offline.
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+ */
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+ if (cpu_online(pp->rxq_def))
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+ elected_cpu = pp->rxq_def;
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- online_cpu_idx = pp->rxq_def % num_online_cpus();
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max_cpu = num_present_cpus();
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for_each_online_cpu(cpu) {
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2018-01-07 14:12:52 +00:00
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@@ -2864,7 +2869,7 @@ static void mvneta_percpu_elect(struct m
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2017-04-17 06:43:54 +00:00
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if ((rxq % max_cpu) == cpu)
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rxq_map |= MVNETA_CPU_RXQ_ACCESS(rxq);
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- if (i == online_cpu_idx)
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+ if (cpu == elected_cpu)
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/* Map the default receive queue queue to the
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* elected CPU
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*/
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2018-01-07 14:12:52 +00:00
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@@ -2875,7 +2880,7 @@ static void mvneta_percpu_elect(struct m
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2017-04-17 06:43:54 +00:00
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* the CPU bound to the default RX queue
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*/
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if (txq_number == 1)
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- txq_map = (i == online_cpu_idx) ?
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+ txq_map = (cpu == elected_cpu) ?
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MVNETA_CPU_TXQ_ACCESS(1) : 0;
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else
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txq_map = mvreg_read(pp, MVNETA_CPU_MAP(cpu)) &
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