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* [PATCH] net: mvpp2: Fix affinity hint allocation
@ 2018-10-30 15:41 Marc Zyngier
  2018-10-30 18:40 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: Marc Zyngier @ 2018-10-30 15:41 UTC (permalink / raw)
  To: davem, Antoine Tenart
  Cc: netdev, linux-kernel, thomas.petazzoni, maxime.chevallier,
	miquel.raynal, gregory.clement, nadavh, stefanc, ymarkman, mw

The mvpp2 driver has the curious behaviour of passing a stack variable
to irq_set_affinity_hint(), which results in the kernel exploding
the first time anyone accesses this information. News flash: userspace
does, and irqbalance will happily take the machine down. Great stuff.

An easy fix is to track the mask within the queue_vector structure,
and to make sure it has the same lifetime as the interrupt itself.

Fixes: e531f76757eb ("net: mvpp2: handle cases where more CPUs are available than s/w threads")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
As requested in https://lore.kernel.org/lkml/20181030135354.GD3407@kwain/

 drivers/net/ethernet/marvell/mvpp2/mvpp2.h     |  1 +
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c    | 18 ++++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
index 176c6b56fdcc..398328f10743 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
@@ -796,6 +796,7 @@ struct mvpp2_queue_vector {
 	int nrxqs;
 	u32 pending_cause_rx;
 	struct mvpp2_port *port;
+	struct cpumask *mask;
 };
 
 struct mvpp2_port {
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 14f9679c957c..7a37a37e3fb3 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -3298,24 +3298,30 @@ static int mvpp2_irqs_init(struct mvpp2_port *port)
 	for (i = 0; i < port->nqvecs; i++) {
 		struct mvpp2_queue_vector *qv = port->qvecs + i;
 
-		if (qv->type == MVPP2_QUEUE_VECTOR_PRIVATE)
+		if (qv->type == MVPP2_QUEUE_VECTOR_PRIVATE) {
+			qv->mask = kzalloc(cpumask_size(), GFP_KERNEL);
+			if (!qv->mask) {
+				err = -ENOMEM;
+				goto err;
+			}
+
 			irq_set_status_flags(qv->irq, IRQ_NO_BALANCING);
+		}
 
 		err = request_irq(qv->irq, mvpp2_isr, 0, port->dev->name, qv);
 		if (err)
 			goto err;
 
 		if (qv->type == MVPP2_QUEUE_VECTOR_PRIVATE) {
-			unsigned long mask = 0;
 			unsigned int cpu;
 
 			for_each_present_cpu(cpu) {
 				if (mvpp2_cpu_to_thread(port->priv, cpu) ==
 				    qv->sw_thread_id)
-					mask |= BIT(cpu);
+					cpumask_set_cpu(cpu, qv->mask);
 			}
 
-			irq_set_affinity_hint(qv->irq, to_cpumask(&mask));
+			irq_set_affinity_hint(qv->irq, qv->mask);
 		}
 	}
 
@@ -3325,6 +3331,8 @@ static int mvpp2_irqs_init(struct mvpp2_port *port)
 		struct mvpp2_queue_vector *qv = port->qvecs + i;
 
 		irq_set_affinity_hint(qv->irq, NULL);
+		kfree(qv->mask);
+		qv->mask = NULL;
 		free_irq(qv->irq, qv);
 	}
 
@@ -3339,6 +3347,8 @@ static void mvpp2_irqs_deinit(struct mvpp2_port *port)
 		struct mvpp2_queue_vector *qv = port->qvecs + i;
 
 		irq_set_affinity_hint(qv->irq, NULL);
+		kfree(qv->mask);
+		qv->mask = NULL;
 		irq_clear_status_flags(qv->irq, IRQ_NO_BALANCING);
 		free_irq(qv->irq, qv);
 	}
-- 
2.19.1


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] net: mvpp2: Fix affinity hint allocation
  2018-10-30 15:41 [PATCH] net: mvpp2: Fix affinity hint allocation Marc Zyngier
@ 2018-10-30 18:40 ` David Miller
  0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2018-10-30 18:40 UTC (permalink / raw)
  To: marc.zyngier
  Cc: antoine.tenart, netdev, linux-kernel, thomas.petazzoni,
	maxime.chevallier, miquel.raynal, gregory.clement, nadavh,
	stefanc, ymarkman, mw

From: Marc Zyngier <marc.zyngier@arm.com>
Date: Tue, 30 Oct 2018 15:41:00 +0000

> The mvpp2 driver has the curious behaviour of passing a stack variable
> to irq_set_affinity_hint(), which results in the kernel exploding
> the first time anyone accesses this information. News flash: userspace
> does, and irqbalance will happily take the machine down. Great stuff.
> 
> An easy fix is to track the mask within the queue_vector structure,
> and to make sure it has the same lifetime as the interrupt itself.
> 
> Fixes: e531f76757eb ("net: mvpp2: handle cases where more CPUs are available than s/w threads")
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> As requested in https://lore.kernel.org/lkml/20181030135354.GD3407@kwain/

Applied.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2018-10-30 18:40 ` David Miller

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