linux-kernel - [PATCH AUTOSEL 4.9 02/24] ARM: 8824/1: fix a migrating irq bug when hotplug cpu

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Message-Id: <20190313191647.160171-2-sashal@kernel.org>
Date:   Wed, 13 Mar 2019 15:16:25 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dietmar Eggemann <dietmar.eggemann@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.9 02/24] ARM: 8824/1: fix a migrating irq bug when hotplug cpu

From: Dietmar Eggemann <dietmar.eggemann@....com>

[ Upstream commit 1b5ba350784242eb1f899bcffd95d2c7cff61e84 ]

Arm TC2 fails cpu hotplug stress test.

This issue was tracked down to a missing copy of the new affinity
cpumask for the vexpress-spc interrupt into struct
irq_common_data.affinity when the interrupt is migrated in
migrate_one_irq().

Fix it by replacing the arm specific hotplug cpu migration with the
generic irq code.

This is the counterpart implementation to commit 217d453d473c ("arm64:
fix a migrating irq bug when hotplug cpu").

Tested with cpu hotplug stress test on Arm TC2 (multi_v7_defconfig plus
CONFIG_ARM_BIG_LITTLE_CPUFREQ=y and CONFIG_ARM_VEXPRESS_SPC_CPUFREQ=y).
The vexpress-spc interrupt (irq=22) on this board is affine to CPU0.
Its affinity cpumask now changes correctly e.g. from 0 to 1-4 when
CPU0 is hotplugged out.

Suggested-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/Kconfig           |  1 +
 arch/arm/include/asm/irq.h |  1 -
 arch/arm/kernel/irq.c      | 62 --------------------------------------
 arch/arm/kernel/smp.c      |  2 +-
 4 files changed, 2 insertions(+), 64 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b5d529fdffab..74a70f91b01a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1457,6 +1457,7 @@ config NR_CPUS
 config HOTPLUG_CPU
 	bool "Support for hot-pluggable CPUs"
 	depends on SMP
+	select GENERIC_IRQ_MIGRATION
 	help
 	  Say Y here to experiment with turning CPUs off and on.  CPUs
 	  can be controlled through /sys/devices/system/cpu.
diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index e53638c8ed8a..61e1d089ce1a 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -24,7 +24,6 @@
 #ifndef __ASSEMBLY__
 struct irqaction;
 struct pt_regs;
-extern void migrate_irqs(void);
 
 extern void asm_do_IRQ(unsigned int, struct pt_regs *);
 void handle_IRQ(unsigned int, struct pt_regs *);
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index ece04a457486..5b07c7a31c31 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -31,7 +31,6 @@
 #include <linux/smp.h>
 #include <linux/init.h>
 #include <linux/seq_file.h>
-#include <linux/ratelimit.h>
 #include <linux/errno.h>
 #include <linux/list.h>
 #include <linux/kallsyms.h>
@@ -119,64 +118,3 @@ int __init arch_probe_nr_irqs(void)
 	return nr_irqs;
 }
 #endif
-
-#ifdef CONFIG_HOTPLUG_CPU
-static bool migrate_one_irq(struct irq_desc *desc)
-{
-	struct irq_data *d = irq_desc_get_irq_data(desc);
-	const struct cpumask *affinity = irq_data_get_affinity_mask(d);
-	struct irq_chip *c;
-	bool ret = false;
-
-	/*
-	 * If this is a per-CPU interrupt, or the affinity does not
-	 * include this CPU, then we have nothing to do.
-	 */
-	if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity))
-		return false;
-
-	if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
-		affinity = cpu_online_mask;
-		ret = true;
-	}
-
-	c = irq_data_get_irq_chip(d);
-	if (!c->irq_set_affinity)
-		pr_debug("IRQ%u: unable to set affinity\n", d->irq);
-	else if (c->irq_set_affinity(d, affinity, false) == IRQ_SET_MASK_OK && ret)
-		cpumask_copy(irq_data_get_affinity_mask(d), affinity);
-
-	return ret;
-}
-
-/*
- * The current CPU has been marked offline.  Migrate IRQs off this CPU.
- * If the affinity settings do not allow other CPUs, force them onto any
- * available CPU.
- *
- * Note: we must iterate over all IRQs, whether they have an attached
- * action structure or not, as we need to get chained interrupts too.
- */
-void migrate_irqs(void)
-{
-	unsigned int i;
-	struct irq_desc *desc;
-	unsigned long flags;
-
-	local_irq_save(flags);
-
-	for_each_irq_desc(i, desc) {
-		bool affinity_broken;
-
-		raw_spin_lock(&desc->lock);
-		affinity_broken = migrate_one_irq(desc);
-		raw_spin_unlock(&desc->lock);
-
-		if (affinity_broken)
-			pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n",
-				i, smp_processor_id());
-	}
-
-	local_irq_restore(flags);
-}
-#endif /* CONFIG_HOTPLUG_CPU */
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8faf869e9fb2..bc83ec7ed53f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -253,7 +253,7 @@ int __cpu_disable(void)
 	/*
 	 * OK - migrate IRQs away from this CPU
 	 */
-	migrate_irqs();
+	irq_migrate_all_off_this_cpu();
 
 	/*
 	 * Flush user cache and TLB mappings, and then remove this CPU
-- 
2.19.1