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Message-Id: <1388938030-16434-1-git-send-email-prarit@redhat.com>
Date: Sun, 5 Jan 2014 11:07:10 -0500
From: Prarit Bhargava <prarit@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Prarit Bhargava <prarit@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Michel Lespinasse <walken@...gle.com>,
Andi Kleen <ak@...ux.intel.com>,
Seiji Aguchi <seiji.aguchi@....com>,
Yang Zhang <yang.z.zhang@...el.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
janet.morgan@...el.com, tony.luck@...el.com, ruiv.wang@...il.com
Subject: [PATCH] x86, Fix do_IRQ interrupt warning for cpu hotplug retriggered irqs [v2]
I tested this by doing a continuous loop of booting a system, downing all
cpus, and then rebooting. Before every reboot I grepped the dmesg log for
the do_IRQ warning to see if there were any additional do_IRQ warnings and
I do not see any after applying this patch. I also tested on several
small and medium sized boxes to confirm that cpu hotplug still works there
too and do not see any issues. Please note that this patchset was tested
in conjunction with
http://marc.info/?l=linux-edac&m=138783131400902&w=2
and
http://marc.info/?l=linux-kernel&m=138871006718478&w=2
in order to get cpu hotplug working.
I'm redoing some additional stability testing (with the additional 2 line
change in this version of the patch) after down'ing all cpus and
bringing them back into service, however, I don't expect to see any new issues.
P.
----8<----
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=64831
When downing a cpu it is possible that there are unhandled irqs left in
the APIC IRR register. The following code path shows how the problem
can occur:
1. CPU 5 is to go down.
2. cpu_disable() on CPU 5 executes with interrupt flag cleared by
local_irq_save() via stop_machine().
3. IRQ 12 asserts on CPU 5, setting IRR but not ISR because interrupt
flag is cleared (CPU unabled to handle the irq)
4. IRQs are migrated off of CPU 5, and the vectors' irqs are set to -1.
5. stop_machine() finishes cpu_disable()
6. cpu_die() for CPU 5 executes in normal context.
7. CPU 5 attempts to handle IRQ 12 because the IRR is set for IRQ 12. The
code attempts to find the vector's IRQ and cannot because it has been set to -1.
8. do_IRQ warning displays warning about CPU 5 IRQ 12.
When this happens, do_IRQ() spits out a warning like
kernel: [ 614.414443] do_IRQ: 5.124 No irq handler for vector (irq -1)
I added a debug printk to output which CPU & vector was retriggered and
discovered that that we are getting bogus events. I see a 100% correlation
between this debug printk in fixup_irqs() and the do_IRQ() warning.
This patchset resolves this by adding definitions for VECTOR_UNDEFINED(-1) and
VECTOR_RETRIGGERED(-2) and modifying the code to use them.
[v2]: sent with more detailed commit message
[v3]: set vector_irq[irq] back to VECTOR_UNDEFINED after call in do_IRQ()
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Michel Lespinasse <walken@...gle.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Seiji Aguchi <seiji.aguchi@....com>
Cc: Yang Zhang <yang.z.zhang@...el.com>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>
Cc: janet.morgan@...el.com
Cc: tony.luck@...el.com
Cc: ruiv.wang@...il.com
---
arch/x86/include/asm/hw_irq.h | 2 ++
arch/x86/kernel/apic/io_apic.c | 13 +++++++------
arch/x86/kernel/irq.c | 20 ++++++++++++++------
arch/x86/kernel/irqinit.c | 4 ++--
4 files changed, 25 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index 92b3bae..22c425e 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -188,6 +188,8 @@ extern __visible void smp_invalidate_interrupt(struct pt_regs *);
extern void (*__initconst interrupt[NR_VECTORS-FIRST_EXTERNAL_VECTOR])(void);
+#define VECTOR_UNDEFINED -1
+#define VECTOR_RETRIGGERED -2
typedef int vector_irq_t[NR_VECTORS];
DECLARE_PER_CPU(vector_irq_t, vector_irq);
extern void setup_vector_irq(int cpu);
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index e63a5bd..6e1541c 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1143,7 +1143,8 @@ next:
goto next;
for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask)
- if (per_cpu(vector_irq, new_cpu)[vector] != -1)
+ if (per_cpu(vector_irq, new_cpu)[vector] >
+ VECTOR_UNDEFINED)
goto next;
/* Found one! */
current_vector = vector;
@@ -1183,7 +1184,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg *cfg)
vector = cfg->vector;
for_each_cpu_and(cpu, cfg->domain, cpu_online_mask)
- per_cpu(vector_irq, cpu)[vector] = -1;
+ per_cpu(vector_irq, cpu)[vector] = VECTOR_UNDEFINED;
cfg->vector = 0;
cpumask_clear(cfg->domain);
@@ -1195,7 +1196,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg *cfg)
vector++) {
if (per_cpu(vector_irq, cpu)[vector] != irq)
continue;
- per_cpu(vector_irq, cpu)[vector] = -1;
+ per_cpu(vector_irq, cpu)[vector] = VECTOR_UNDEFINED;
break;
}
}
@@ -1228,12 +1229,12 @@ void __setup_vector_irq(int cpu)
/* Mark the free vectors */
for (vector = 0; vector < NR_VECTORS; ++vector) {
irq = per_cpu(vector_irq, cpu)[vector];
- if (irq < 0)
+ if (irq <= VECTOR_UNDEFINED)
continue;
cfg = irq_cfg(irq);
if (!cpumask_test_cpu(cpu, cfg->domain))
- per_cpu(vector_irq, cpu)[vector] = -1;
+ per_cpu(vector_irq, cpu)[vector] = VECTOR_UNDEFINED;
}
raw_spin_unlock(&vector_lock);
}
@@ -2208,7 +2209,7 @@ asmlinkage void smp_irq_move_cleanup_interrupt(void)
struct irq_cfg *cfg;
irq = __this_cpu_read(vector_irq[vector]);
- if (irq == -1)
+ if (irq <= VECTOR_UNDEFINED)
continue;
desc = irq_to_desc(irq);
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 22d0687..aa7c049 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -193,9 +193,13 @@ __visible unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
if (!handle_irq(irq, regs)) {
ack_APIC_irq();
- if (printk_ratelimit())
- pr_emerg("%s: %d.%d No irq handler for vector (irq %d)\n",
- __func__, smp_processor_id(), vector, irq);
+ if (irq != VECTOR_RETRIGGERED)
+ pr_emerg_ratelimited("%s: %d.%d No irq handler for vector (irq %d)\n",
+ __func__, smp_processor_id(),
+ vector, irq);
+ else
+ __this_cpu_write(vector_irq[vector],
+ VECTOR_UNDEFINED);
}
irq_exit();
@@ -344,7 +348,7 @@ void fixup_irqs(void)
for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
unsigned int irr;
- if (__this_cpu_read(vector_irq[vector]) < 0)
+ if (__this_cpu_read(vector_irq[vector]) <= VECTOR_UNDEFINED)
continue;
irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
@@ -355,11 +359,15 @@ void fixup_irqs(void)
data = irq_desc_get_irq_data(desc);
chip = irq_data_get_irq_chip(data);
raw_spin_lock(&desc->lock);
- if (chip->irq_retrigger)
+ if (chip->irq_retrigger) {
chip->irq_retrigger(data);
+ __this_cpu_write(vector_irq[vector],
+ VECTOR_RETRIGGERED);
+ }
raw_spin_unlock(&desc->lock);
}
- __this_cpu_write(vector_irq[vector], -1);
+ if (__this_cpu_read(vector_irq[vector]) != VECTOR_RETRIGGERED)
+ __this_cpu_write(vector_irq[vector], VECTOR_UNDEFINED);
}
}
#endif
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index a2a1fbc..7f50156 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -52,7 +52,7 @@ static struct irqaction irq2 = {
};
DEFINE_PER_CPU(vector_irq_t, vector_irq) = {
- [0 ... NR_VECTORS - 1] = -1,
+ [0 ... NR_VECTORS - 1] = VECTOR_UNDEFINED,
};
int vector_used_by_percpu_irq(unsigned int vector)
@@ -60,7 +60,7 @@ int vector_used_by_percpu_irq(unsigned int vector)
int cpu;
for_each_online_cpu(cpu) {
- if (per_cpu(vector_irq, cpu)[vector] != -1)
+ if (per_cpu(vector_irq, cpu)[vector] > VECTOR_UNDEFINED)
return 1;
}
--
1.7.9.3
--
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