![Ingo Molnar](/assets/img/avatar_default.png)
while porting the -rt tree to 2.6.18-rc7 i noticed the following screaming-IRQ scenario on an SMP system: 2274 0Dn.:1 0.001ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.010ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.020ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.029ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.039ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.048ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.058ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.068ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.077ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.087ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) 2274 0Dn.:1 0.097ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf) as it turns out, the bug is caused by handle_level_irq(), which if it races with another CPU already handling this IRQ, it _unmasks_ the IRQ line on the way out. This is not how 2.6.17 works, and we introduced this bug in one of the early genirq cleanups right before it went into -mm. (the bug was not in the genirq patchset for a long time, and we didnt notice the bug due to the lack of -rt rebase to the new genirq code. -rt, and hardirq-preemption in particular opens up such races much wider than anything else.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
538 lines
13 KiB
C
538 lines
13 KiB
C
/*
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* linux/kernel/irq/chip.c
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*
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* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
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* Copyright (C) 2005-2006, Thomas Gleixner, Russell King
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*
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* This file contains the core interrupt handling code, for irq-chip
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* based architectures.
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*
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* Detailed information is available in Documentation/DocBook/genericirq
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*/
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include "internals.h"
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/**
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* set_irq_chip - set the irq chip for an irq
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* @irq: irq number
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* @chip: pointer to irq chip description structure
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*/
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int set_irq_chip(unsigned int irq, struct irq_chip *chip)
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{
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struct irq_desc *desc;
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unsigned long flags;
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if (irq >= NR_IRQS) {
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printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
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WARN_ON(1);
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return -EINVAL;
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}
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if (!chip)
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chip = &no_irq_chip;
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desc = irq_desc + irq;
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spin_lock_irqsave(&desc->lock, flags);
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irq_chip_set_defaults(chip);
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desc->chip = chip;
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/*
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* For compatibility only:
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*/
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desc->chip = chip;
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spin_unlock_irqrestore(&desc->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL(set_irq_chip);
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/**
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* set_irq_type - set the irq type for an irq
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* @irq: irq number
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* @type: interrupt type - see include/linux/interrupt.h
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*/
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int set_irq_type(unsigned int irq, unsigned int type)
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{
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struct irq_desc *desc;
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unsigned long flags;
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int ret = -ENXIO;
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if (irq >= NR_IRQS) {
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printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
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return -ENODEV;
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}
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desc = irq_desc + irq;
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if (desc->chip->set_type) {
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spin_lock_irqsave(&desc->lock, flags);
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ret = desc->chip->set_type(irq, type);
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spin_unlock_irqrestore(&desc->lock, flags);
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}
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return ret;
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}
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EXPORT_SYMBOL(set_irq_type);
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/**
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* set_irq_data - set irq type data for an irq
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* @irq: Interrupt number
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* @data: Pointer to interrupt specific data
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*
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* Set the hardware irq controller data for an irq
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*/
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int set_irq_data(unsigned int irq, void *data)
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{
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struct irq_desc *desc;
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unsigned long flags;
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if (irq >= NR_IRQS) {
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printk(KERN_ERR
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"Trying to install controller data for IRQ%d\n", irq);
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return -EINVAL;
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}
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desc = irq_desc + irq;
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spin_lock_irqsave(&desc->lock, flags);
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desc->handler_data = data;
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spin_unlock_irqrestore(&desc->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL(set_irq_data);
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/**
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* set_irq_chip_data - set irq chip data for an irq
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* @irq: Interrupt number
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* @data: Pointer to chip specific data
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*
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* Set the hardware irq chip data for an irq
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*/
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int set_irq_chip_data(unsigned int irq, void *data)
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{
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struct irq_desc *desc = irq_desc + irq;
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unsigned long flags;
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if (irq >= NR_IRQS || !desc->chip) {
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printk(KERN_ERR "BUG: bad set_irq_chip_data(IRQ#%d)\n", irq);
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return -EINVAL;
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}
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spin_lock_irqsave(&desc->lock, flags);
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desc->chip_data = data;
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spin_unlock_irqrestore(&desc->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL(set_irq_chip_data);
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/*
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* default enable function
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*/
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static void default_enable(unsigned int irq)
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{
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struct irq_desc *desc = irq_desc + irq;
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desc->chip->unmask(irq);
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desc->status &= ~IRQ_MASKED;
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}
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/*
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* default disable function
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*/
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static void default_disable(unsigned int irq)
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{
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struct irq_desc *desc = irq_desc + irq;
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if (!(desc->status & IRQ_DELAYED_DISABLE))
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irq_desc[irq].chip->mask(irq);
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}
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/*
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* default startup function
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*/
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static unsigned int default_startup(unsigned int irq)
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{
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irq_desc[irq].chip->enable(irq);
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return 0;
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}
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/*
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* Fixup enable/disable function pointers
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*/
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void irq_chip_set_defaults(struct irq_chip *chip)
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{
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if (!chip->enable)
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chip->enable = default_enable;
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if (!chip->disable)
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chip->disable = default_disable;
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if (!chip->startup)
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chip->startup = default_startup;
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if (!chip->shutdown)
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chip->shutdown = chip->disable;
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if (!chip->name)
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chip->name = chip->typename;
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}
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static inline void mask_ack_irq(struct irq_desc *desc, int irq)
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{
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if (desc->chip->mask_ack)
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desc->chip->mask_ack(irq);
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else {
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desc->chip->mask(irq);
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desc->chip->ack(irq);
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}
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}
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/**
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* handle_simple_irq - Simple and software-decoded IRQs.
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* @irq: the interrupt number
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* @desc: the interrupt description structure for this irq
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* @regs: pointer to a register structure
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*
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* Simple interrupts are either sent from a demultiplexing interrupt
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* handler or come from hardware, where no interrupt hardware control
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* is necessary.
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*
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* Note: The caller is expected to handle the ack, clear, mask and
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* unmask issues if necessary.
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*/
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void fastcall
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handle_simple_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
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{
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struct irqaction *action;
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irqreturn_t action_ret;
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const unsigned int cpu = smp_processor_id();
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spin_lock(&desc->lock);
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if (unlikely(desc->status & IRQ_INPROGRESS))
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goto out_unlock;
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desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
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kstat_cpu(cpu).irqs[irq]++;
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action = desc->action;
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if (unlikely(!action || (desc->status & IRQ_DISABLED)))
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goto out_unlock;
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desc->status |= IRQ_INPROGRESS;
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spin_unlock(&desc->lock);
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action_ret = handle_IRQ_event(irq, regs, action);
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if (!noirqdebug)
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note_interrupt(irq, desc, action_ret, regs);
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spin_lock(&desc->lock);
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desc->status &= ~IRQ_INPROGRESS;
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out_unlock:
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spin_unlock(&desc->lock);
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}
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/**
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* handle_level_irq - Level type irq handler
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* @irq: the interrupt number
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* @desc: the interrupt description structure for this irq
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* @regs: pointer to a register structure
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*
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* Level type interrupts are active as long as the hardware line has
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* the active level. This may require to mask the interrupt and unmask
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* it after the associated handler has acknowledged the device, so the
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* interrupt line is back to inactive.
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*/
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void fastcall
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handle_level_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
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{
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unsigned int cpu = smp_processor_id();
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struct irqaction *action;
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irqreturn_t action_ret;
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spin_lock(&desc->lock);
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mask_ack_irq(desc, irq);
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if (unlikely(desc->status & IRQ_INPROGRESS))
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goto out_unlock;
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desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
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kstat_cpu(cpu).irqs[irq]++;
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/*
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* If its disabled or no action available
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* keep it masked and get out of here
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*/
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action = desc->action;
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if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
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desc->status |= IRQ_PENDING;
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goto out_unlock;
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}
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desc->status |= IRQ_INPROGRESS;
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desc->status &= ~IRQ_PENDING;
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spin_unlock(&desc->lock);
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action_ret = handle_IRQ_event(irq, regs, action);
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if (!noirqdebug)
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note_interrupt(irq, desc, action_ret, regs);
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spin_lock(&desc->lock);
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desc->status &= ~IRQ_INPROGRESS;
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if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
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desc->chip->unmask(irq);
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out_unlock:
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spin_unlock(&desc->lock);
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}
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/**
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* handle_fasteoi_irq - irq handler for transparent controllers
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* @irq: the interrupt number
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* @desc: the interrupt description structure for this irq
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* @regs: pointer to a register structure
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*
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* Only a single callback will be issued to the chip: an ->eoi()
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* call when the interrupt has been serviced. This enables support
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* for modern forms of interrupt handlers, which handle the flow
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* details in hardware, transparently.
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*/
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void fastcall
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handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc,
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struct pt_regs *regs)
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{
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unsigned int cpu = smp_processor_id();
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struct irqaction *action;
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irqreturn_t action_ret;
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spin_lock(&desc->lock);
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if (unlikely(desc->status & IRQ_INPROGRESS))
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goto out;
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desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
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kstat_cpu(cpu).irqs[irq]++;
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/*
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* If its disabled or no action available
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* keep it masked and get out of here
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*/
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action = desc->action;
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if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
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desc->status |= IRQ_PENDING;
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goto out;
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}
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desc->status |= IRQ_INPROGRESS;
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desc->status &= ~IRQ_PENDING;
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spin_unlock(&desc->lock);
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action_ret = handle_IRQ_event(irq, regs, action);
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if (!noirqdebug)
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note_interrupt(irq, desc, action_ret, regs);
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spin_lock(&desc->lock);
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desc->status &= ~IRQ_INPROGRESS;
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out:
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desc->chip->eoi(irq);
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spin_unlock(&desc->lock);
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}
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/**
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* handle_edge_irq - edge type IRQ handler
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* @irq: the interrupt number
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* @desc: the interrupt description structure for this irq
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* @regs: pointer to a register structure
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*
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* Interrupt occures on the falling and/or rising edge of a hardware
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* signal. The occurence is latched into the irq controller hardware
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* and must be acked in order to be reenabled. After the ack another
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* interrupt can happen on the same source even before the first one
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* is handled by the assosiacted event handler. If this happens it
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* might be necessary to disable (mask) the interrupt depending on the
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* controller hardware. This requires to reenable the interrupt inside
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* of the loop which handles the interrupts which have arrived while
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* the handler was running. If all pending interrupts are handled, the
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* loop is left.
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*/
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void fastcall
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handle_edge_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
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{
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const unsigned int cpu = smp_processor_id();
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spin_lock(&desc->lock);
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desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
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/*
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* If we're currently running this IRQ, or its disabled,
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* we shouldn't process the IRQ. Mark it pending, handle
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* the necessary masking and go out
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*/
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if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED)) ||
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!desc->action)) {
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desc->status |= (IRQ_PENDING | IRQ_MASKED);
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mask_ack_irq(desc, irq);
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goto out_unlock;
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}
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kstat_cpu(cpu).irqs[irq]++;
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/* Start handling the irq */
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desc->chip->ack(irq);
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/* Mark the IRQ currently in progress.*/
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desc->status |= IRQ_INPROGRESS;
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do {
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struct irqaction *action = desc->action;
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irqreturn_t action_ret;
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if (unlikely(!action)) {
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desc->chip->mask(irq);
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goto out_unlock;
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}
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/*
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* When another irq arrived while we were handling
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* one, we could have masked the irq.
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* Renable it, if it was not disabled in meantime.
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*/
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if (unlikely((desc->status &
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(IRQ_PENDING | IRQ_MASKED | IRQ_DISABLED)) ==
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(IRQ_PENDING | IRQ_MASKED))) {
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desc->chip->unmask(irq);
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desc->status &= ~IRQ_MASKED;
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}
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desc->status &= ~IRQ_PENDING;
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spin_unlock(&desc->lock);
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action_ret = handle_IRQ_event(irq, regs, action);
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if (!noirqdebug)
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note_interrupt(irq, desc, action_ret, regs);
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spin_lock(&desc->lock);
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} while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
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desc->status &= ~IRQ_INPROGRESS;
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out_unlock:
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spin_unlock(&desc->lock);
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}
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#ifdef CONFIG_SMP
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/**
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* handle_percpu_IRQ - Per CPU local irq handler
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* @irq: the interrupt number
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* @desc: the interrupt description structure for this irq
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* @regs: pointer to a register structure
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*
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* Per CPU interrupts on SMP machines without locking requirements
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*/
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void fastcall
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handle_percpu_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
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{
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irqreturn_t action_ret;
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kstat_this_cpu.irqs[irq]++;
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if (desc->chip->ack)
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desc->chip->ack(irq);
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action_ret = handle_IRQ_event(irq, regs, desc->action);
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if (!noirqdebug)
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note_interrupt(irq, desc, action_ret, regs);
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if (desc->chip->eoi)
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desc->chip->eoi(irq);
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}
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#endif /* CONFIG_SMP */
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void
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__set_irq_handler(unsigned int irq,
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void fastcall (*handle)(unsigned int, irq_desc_t *,
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struct pt_regs *),
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int is_chained)
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{
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struct irq_desc *desc;
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unsigned long flags;
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if (irq >= NR_IRQS) {
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printk(KERN_ERR
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"Trying to install type control for IRQ%d\n", irq);
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return;
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}
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desc = irq_desc + irq;
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if (!handle)
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handle = handle_bad_irq;
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if (desc->chip == &no_irq_chip) {
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printk(KERN_WARNING "Trying to install %sinterrupt handler "
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"for IRQ%d\n", is_chained ? "chained " : " ", irq);
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/*
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* Some ARM implementations install a handler for really dumb
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* interrupt hardware without setting an irq_chip. This worked
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* with the ARM no_irq_chip but the check in setup_irq would
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* prevent us to setup the interrupt at all. Switch it to
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* dummy_irq_chip for easy transition.
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*/
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desc->chip = &dummy_irq_chip;
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}
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spin_lock_irqsave(&desc->lock, flags);
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/* Uninstall? */
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if (handle == handle_bad_irq) {
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if (desc->chip != &no_irq_chip) {
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desc->chip->mask(irq);
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desc->chip->ack(irq);
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}
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desc->status |= IRQ_DISABLED;
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desc->depth = 1;
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}
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desc->handle_irq = handle;
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if (handle != handle_bad_irq && is_chained) {
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desc->status &= ~IRQ_DISABLED;
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desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
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desc->depth = 0;
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desc->chip->unmask(irq);
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}
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spin_unlock_irqrestore(&desc->lock, flags);
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}
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void
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set_irq_chip_and_handler(unsigned int irq, struct irq_chip *chip,
|
|
void fastcall (*handle)(unsigned int,
|
|
struct irq_desc *,
|
|
struct pt_regs *))
|
|
{
|
|
set_irq_chip(irq, chip);
|
|
__set_irq_handler(irq, handle, 0);
|
|
}
|
|
|
|
/*
|
|
* Get a descriptive string for the highlevel handler, for
|
|
* /proc/interrupts output:
|
|
*/
|
|
const char *
|
|
handle_irq_name(void fastcall (*handle)(unsigned int, struct irq_desc *,
|
|
struct pt_regs *))
|
|
{
|
|
if (handle == handle_level_irq)
|
|
return "level ";
|
|
if (handle == handle_fasteoi_irq)
|
|
return "fasteoi";
|
|
if (handle == handle_edge_irq)
|
|
return "edge ";
|
|
if (handle == handle_simple_irq)
|
|
return "simple ";
|
|
#ifdef CONFIG_SMP
|
|
if (handle == handle_percpu_irq)
|
|
return "percpu ";
|
|
#endif
|
|
if (handle == handle_bad_irq)
|
|
return "bad ";
|
|
|
|
return NULL;
|
|
}
|