android_kernel_xiaomi_sm8350/arch/x86_64/kernel/irq.c
Siddha, Suresh B 48d8d7ee5d x86_64 irq: use mask/unmask and proper locking in fixup_irqs()
Force irq migration path during cpu offline, is not using proper locks and
irq_chip mask/unmask routines.  This will result in some races(especially
the device generating the interrupt can see some inconsistent state,
resulting in issues like stuck irq,..).

Appended patch fixes the issue by taking proper lock and encapsulating
irq_chip set_affinity() with a mask() before and an unmask() after.

This fixes a MSI irq stuck issue reported by Darrick Wong.

There are several more general bugs in this area(irq migration in the
process context). For example,

 1. Possibility of missing edge triggered irq.
 2. Reliable method of migrating level triggered irq in the process context.

We plan to look and close these in the near future.

Eric says:
	In addition even with the fix from Suresh there is still at least one
	nasty hardware race in fixup_irqs().   However we exercise that code
	path rarely enough that we are unlikely to hit it in the real world,
	and that race seems to have existed since the code was merged.  And a
	fix for that is not coming soon as it is an open investigation area
	if we can fix irq migration to work outside of irq context or if
	we have to rework the requirements imposed by the generic cpu hotplug
	and layer on fixup_irqs().  So this may come up again.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Reported-and-tested-by: Darrick Wong <djwong@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-26 16:54:29 -07:00

214 lines
4.8 KiB
C

/*
* linux/arch/x86_64/kernel/irq.c
*
* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
*
* This file contains the lowest level x86_64-specific interrupt
* entry and irq statistics code. All the remaining irq logic is
* done by the generic kernel/irq/ code and in the
* x86_64-specific irq controller code. (e.g. i8259.c and
* io_apic.c.)
*/
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/io_apic.h>
#include <asm/idle.h>
#include <asm/smp.h>
atomic_t irq_err_count;
#ifdef CONFIG_DEBUG_STACKOVERFLOW
/*
* Probabilistic stack overflow check:
*
* Only check the stack in process context, because everything else
* runs on the big interrupt stacks. Checking reliably is too expensive,
* so we just check from interrupts.
*/
static inline void stack_overflow_check(struct pt_regs *regs)
{
u64 curbase = (u64)task_stack_page(current);
static unsigned long warned = -60*HZ;
if (regs->rsp >= curbase && regs->rsp <= curbase + THREAD_SIZE &&
regs->rsp < curbase + sizeof(struct thread_info) + 128 &&
time_after(jiffies, warned + 60*HZ)) {
printk("do_IRQ: %s near stack overflow (cur:%Lx,rsp:%lx)\n",
current->comm, curbase, regs->rsp);
show_stack(NULL,NULL);
warned = jiffies;
}
}
#endif
/*
* Generic, controller-independent functions:
*/
int show_interrupts(struct seq_file *p, void *v)
{
int i = *(loff_t *) v, j;
struct irqaction * action;
unsigned long flags;
if (i == 0) {
seq_printf(p, " ");
for_each_online_cpu(j)
seq_printf(p, "CPU%-8d",j);
seq_putc(p, '\n');
}
if (i < NR_IRQS) {
spin_lock_irqsave(&irq_desc[i].lock, flags);
action = irq_desc[i].action;
if (!action)
goto skip;
seq_printf(p, "%3d: ",i);
#ifndef CONFIG_SMP
seq_printf(p, "%10u ", kstat_irqs(i));
#else
for_each_online_cpu(j)
seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#endif
seq_printf(p, " %8s", irq_desc[i].chip->name);
seq_printf(p, "-%-8s", irq_desc[i].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');
skip:
spin_unlock_irqrestore(&irq_desc[i].lock, flags);
} else if (i == NR_IRQS) {
seq_printf(p, "NMI: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ", cpu_pda(j)->__nmi_count);
seq_putc(p, '\n');
seq_printf(p, "LOC: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ", cpu_pda(j)->apic_timer_irqs);
seq_putc(p, '\n');
seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
}
return 0;
}
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
* handlers).
*/
asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
/* high bit used in ret_from_ code */
unsigned vector = ~regs->orig_rax;
unsigned irq;
exit_idle();
irq_enter();
irq = __get_cpu_var(vector_irq)[vector];
#ifdef CONFIG_DEBUG_STACKOVERFLOW
stack_overflow_check(regs);
#endif
if (likely(irq < NR_IRQS))
generic_handle_irq(irq);
else {
if (!disable_apic)
ack_APIC_irq();
if (printk_ratelimit())
printk(KERN_EMERG "%s: %d.%d No irq handler for vector\n",
__func__, smp_processor_id(), vector);
}
irq_exit();
set_irq_regs(old_regs);
return 1;
}
#ifdef CONFIG_HOTPLUG_CPU
void fixup_irqs(cpumask_t map)
{
unsigned int irq;
static int warned;
for (irq = 0; irq < NR_IRQS; irq++) {
cpumask_t mask;
int break_affinity = 0;
int set_affinity = 1;
if (irq == 2)
continue;
/* interrupt's are disabled at this point */
spin_lock(&irq_desc[irq].lock);
if (!irq_has_action(irq) ||
cpus_equal(irq_desc[irq].affinity, map)) {
spin_unlock(&irq_desc[irq].lock);
continue;
}
cpus_and(mask, irq_desc[irq].affinity, map);
if (cpus_empty(mask)) {
break_affinity = 1;
mask = map;
}
if (irq_desc[irq].chip->mask)
irq_desc[irq].chip->mask(irq);
if (irq_desc[irq].chip->set_affinity)
irq_desc[irq].chip->set_affinity(irq, mask);
else if (!(warned++))
set_affinity = 0;
if (irq_desc[irq].chip->unmask)
irq_desc[irq].chip->unmask(irq);
spin_unlock(&irq_desc[irq].lock);
if (break_affinity && set_affinity)
printk("Broke affinity for irq %i\n", irq);
else if (!set_affinity)
printk("Cannot set affinity for irq %i\n", irq);
}
/* That doesn't seem sufficient. Give it 1ms. */
local_irq_enable();
mdelay(1);
local_irq_disable();
}
#endif
extern void call_softirq(void);
asmlinkage void do_softirq(void)
{
__u32 pending;
unsigned long flags;
if (in_interrupt())
return;
local_irq_save(flags);
pending = local_softirq_pending();
/* Switch to interrupt stack */
if (pending) {
call_softirq();
WARN_ON_ONCE(softirq_count());
}
local_irq_restore(flags);
}
EXPORT_SYMBOL(do_softirq);