Re: [RFC PATCH v1 4/4] arm/arm64: fix a migrating irq bug when hotplug cpu

From: Yang Yingliang
Date: Sun Sep 06 2015 - 22:34:36 EST


On 2015/9/6 13:55, Jiang Liu wrote:


On 2015/9/6 12:23, Yang Yingliang wrote:
When cpu is disabled, all irqs will be migratged to another cpu.
In some cases, a new affinity is different, it needed to be coppied
to irq's affinity. But if the type of irq is LPI, it's affinity will
not be coppied because of irq_set_affinity's return value. Fix it by
using irq_do_set_affinity.

And migrating interrupts is a core code matter, so move the code to
kernel/irq/migration.c and select CONFIG_GENERIC_IRQ_MIGRATION when
CONFIG_HOTPLUG_CPU and CONFIG_SMP is enabled.

Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>
Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/irq.h | 1 -
arch/arm/kernel/irq.c | 62 --------------------------------------------
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/irq.h | 1 -
arch/arm64/kernel/irq.c | 62 --------------------------------------------
kernel/irq/migration.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
7 files changed, 64 insertions(+), 126 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 41cbb4a..ebc8a33 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -22,6 +22,7 @@ config ARM
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_PROBE
+ select GENERIC_IRQ_MIGRATION if SMP && HOTPLUG_CPU
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_PCI_IOMAP
diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index 53c15de..d17fc900 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 baf8ede..2efdb40 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>
@@ -135,64 +134,3 @@ 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/arm64/Kconfig b/arch/arm64/Kconfig
index b7b9cea..6ffe411 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -32,6 +32,7 @@ config ARM64
select GENERIC_CPU_AUTOPROBE
select GENERIC_EARLY_IOREMAP
select GENERIC_IRQ_PROBE
+ select GENERIC_IRQ_MIGRATION if SMP && HOTPLUG_CPU
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_PCI_IOMAP
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index bbb251b..0916929 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -7,7 +7,6 @@

struct pt_regs;

-extern void migrate_irqs(void);
extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));

static inline void acpi_irq_init(void)
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 463fa2e..04ac1f6 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -27,7 +27,6 @@
#include <linux/init.h>
#include <linux/irqchip.h>
#include <linux/seq_file.h>
-#include <linux/ratelimit.h>

unsigned long irq_err_count;

@@ -56,64 +55,3 @@ void __init init_IRQ(void)
if (!handle_arch_irq)
panic("No interrupt controller found.");
}
-
-#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/kernel/irq/migration.c b/kernel/irq/migration.c
index 37ddb7b..5801c79 100644
--- a/kernel/irq/migration.c
+++ b/kernel/irq/migration.c
@@ -1,6 +1,7 @@

#include <linux/irq.h>
#include <linux/interrupt.h>
+#include <linux/ratelimit.h>

#include "internals.h"

@@ -77,3 +78,64 @@ void irq_move_irq(struct irq_data *idata)
if (!masked)
idata->chip->irq_unmask(idata);
}
+
+#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 = d->affinity;
+ 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);
How about pr_warn here? It may cause serious drawback if this happens.
I think so, I will change it next version.

+ else
+ irq_do_set_affinity(d, affinity, false);
Should we check return value here?

The return value is not used, so we don't check it.
Maybe I could add some warning by checking it.
+
+ 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) {
Should we use for_each_active_irq() here to iterate over active
irqs only?

It looks good. I will use it next version.
+ 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 */


.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/