linux/arch/arm/kernel/irq.c
Russell King 617912440b ARM: irq migration: ensure migration is handled safely
Ensure appropriate locks are taken to ensure that IRQ migration off
the current CPU is race-free.  We may have a concurrent set_affinity
via procfs running on another CPU in parallel with the IRQ migration,
resulting in unpredictable results.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-23 17:24:16 +00:00

235 lines
5.5 KiB
C

/*
* linux/arch/arm/kernel/irq.c
*
* Copyright (C) 1992 Linus Torvalds
* Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
*
* Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
* Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
* Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This file contains the code used by various IRQ handling routines:
* asking for different IRQ's should be done through these routines
* instead of just grabbing them. Thus setups with different IRQ numbers
* shouldn't result in any weird surprises, and installing new handlers
* should be easier.
*
* IRQ's are in fact implemented a bit like signal handlers for the kernel.
* Naturally it's not a 1:1 relation, but there are similarities.
*/
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/signal.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/random.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/kallsyms.h>
#include <linux/proc_fs.h>
#include <linux/ftrace.h>
#include <asm/system.h>
#include <asm/mach/arch.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
/*
* No architecture-specific irq_finish function defined in arm/arch/irqs.h.
*/
#ifndef irq_finish
#define irq_finish(irq) do { } while (0)
#endif
unsigned long irq_err_count;
int show_interrupts(struct seq_file *p, void *v)
{
int i = *(loff_t *) v, cpu;
struct irq_desc *desc;
struct irqaction * action;
unsigned long flags;
int prec, n;
for (prec = 3, n = 1000; prec < 10 && n <= nr_irqs; prec++)
n *= 10;
#ifdef CONFIG_SMP
if (prec < 4)
prec = 4;
#endif
if (i == 0) {
char cpuname[12];
seq_printf(p, "%*s ", prec, "");
for_each_present_cpu(cpu) {
sprintf(cpuname, "CPU%d", cpu);
seq_printf(p, " %10s", cpuname);
}
seq_putc(p, '\n');
}
if (i < nr_irqs) {
desc = irq_to_desc(i);
raw_spin_lock_irqsave(&desc->lock, flags);
action = desc->action;
if (!action)
goto unlock;
seq_printf(p, "%*d: ", prec, i);
for_each_present_cpu(cpu)
seq_printf(p, "%10u ", kstat_irqs_cpu(i, cpu));
seq_printf(p, " %10s", desc->irq_data.chip->name ? : "-");
seq_printf(p, " %s", action->name);
for (action = action->next; action; action = action->next)
seq_printf(p, ", %s", action->name);
seq_putc(p, '\n');
unlock:
raw_spin_unlock_irqrestore(&desc->lock, flags);
} else if (i == nr_irqs) {
#ifdef CONFIG_FIQ
show_fiq_list(p, prec);
#endif
#ifdef CONFIG_SMP
show_ipi_list(p, prec);
#endif
#ifdef CONFIG_LOCAL_TIMERS
show_local_irqs(p, prec);
#endif
seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
}
return 0;
}
/*
* do_IRQ handles all hardware IRQ's. Decoded IRQs should not
* come via this function. Instead, they should provide their
* own 'handler'
*/
asmlinkage void __exception_irq_entry
asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
irq_enter();
/*
* Some hardware gives randomly wrong interrupts. Rather
* than crashing, do something sensible.
*/
if (unlikely(irq >= nr_irqs)) {
if (printk_ratelimit())
printk(KERN_WARNING "Bad IRQ%u\n", irq);
ack_bad_irq(irq);
} else {
generic_handle_irq(irq);
}
/* AT91 specific workaround */
irq_finish(irq);
irq_exit();
set_irq_regs(old_regs);
}
void set_irq_flags(unsigned int irq, unsigned int iflags)
{
struct irq_desc *desc;
unsigned long flags;
if (irq >= nr_irqs) {
printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
return;
}
desc = irq_to_desc(irq);
raw_spin_lock_irqsave(&desc->lock, flags);
desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
if (iflags & IRQF_VALID)
desc->status &= ~IRQ_NOREQUEST;
if (iflags & IRQF_PROBE)
desc->status &= ~IRQ_NOPROBE;
if (!(iflags & IRQF_NOAUTOEN))
desc->status &= ~IRQ_NOAUTOEN;
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
void __init init_IRQ(void)
{
machine_desc->init_irq();
}
#ifdef CONFIG_SPARSE_IRQ
int __init arch_probe_nr_irqs(void)
{
nr_irqs = machine_desc->nr_irqs ? machine_desc->nr_irqs : NR_IRQS;
return nr_irqs;
}
#endif
#ifdef CONFIG_HOTPLUG_CPU
static bool migrate_one_irq(struct irq_data *d)
{
unsigned int cpu = cpumask_any_and(d->affinity, cpu_online_mask);
bool ret = false;
if (cpu >= nr_cpu_ids) {
cpu = cpumask_any(cpu_online_mask);
ret = true;
}
pr_debug("IRQ%u: moving from cpu%u to cpu%u\n", d->irq, d->node, cpu);
d->chip->irq_set_affinity(d, cpumask_of(cpu), true);
return ret;
}
/*
* The 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.
*/
void migrate_irqs(void)
{
unsigned int i, cpu = smp_processor_id();
struct irq_desc *desc;
unsigned long flags;
local_irq_save(flags);
for_each_irq_desc(i, desc) {
struct irq_data *d = &desc->irq_data;
bool affinity_broken = false;
raw_spin_lock(&desc->lock);
do {
if (desc->action == NULL)
break;
if (d->node != cpu)
break;
affinity_broken = migrate_one_irq(d);
} while (0);
raw_spin_unlock(&desc->lock);
if (affinity_broken && printk_ratelimit())
pr_warning("IRQ%u no longer affine to CPU%u\n", i, cpu);
}
local_irq_restore(flags);
}
#endif /* CONFIG_HOTPLUG_CPU */