forked from luck/tmp_suning_uos_patched
a98ce5c6fe
As it is some callers of synchronize_irq rely on memory barriers to provide synchronisation against the IRQ handlers. For example, the tg3 driver does tp->irq_sync = 1; smp_mb(); synchronize_irq(); and then in the IRQ handler: if (!tp->irq_sync) netif_rx_schedule(dev, &tp->napi); Unfortunately memory barriers only work well when they come in pairs. Because we don't actually have memory barriers on the IRQ path, the memory barrier before the synchronize_irq() doesn't actually protect us. In particular, synchronize_irq() may return followed by the result of netif_rx_schedule being made visible. This patch (mostly written by Linus) fixes this by using spin locks instead of memory barries on the synchronize_irq() path. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
580 lines
14 KiB
C
580 lines
14 KiB
C
/*
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* linux/kernel/irq/manage.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
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*
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* This file contains driver APIs to the irq subsystem.
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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/random.h>
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#include <linux/interrupt.h>
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#include "internals.h"
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#ifdef CONFIG_SMP
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/**
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* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
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* @irq: interrupt number to wait for
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*
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* This function waits for any pending IRQ handlers for this interrupt
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* to complete before returning. If you use this function while
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* holding a resource the IRQ handler may need you will deadlock.
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*
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* This function may be called - with care - from IRQ context.
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*/
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void synchronize_irq(unsigned int irq)
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{
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struct irq_desc *desc = irq_desc + irq;
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unsigned int status;
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if (irq >= NR_IRQS)
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return;
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do {
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unsigned long flags;
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/*
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* Wait until we're out of the critical section. This might
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* give the wrong answer due to the lack of memory barriers.
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*/
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while (desc->status & IRQ_INPROGRESS)
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cpu_relax();
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/* Ok, that indicated we're done: double-check carefully. */
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spin_lock_irqsave(&desc->lock, flags);
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status = desc->status;
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spin_unlock_irqrestore(&desc->lock, flags);
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/* Oops, that failed? */
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} while (status & IRQ_INPROGRESS);
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}
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EXPORT_SYMBOL(synchronize_irq);
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/**
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* irq_can_set_affinity - Check if the affinity of a given irq can be set
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* @irq: Interrupt to check
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*
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*/
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int irq_can_set_affinity(unsigned int irq)
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{
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struct irq_desc *desc = irq_desc + irq;
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if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
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!desc->chip->set_affinity)
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return 0;
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return 1;
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}
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/**
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* irq_set_affinity - Set the irq affinity of a given irq
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* @irq: Interrupt to set affinity
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* @cpumask: cpumask
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*
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*/
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int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
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{
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struct irq_desc *desc = irq_desc + irq;
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if (!desc->chip->set_affinity)
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return -EINVAL;
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set_balance_irq_affinity(irq, cpumask);
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#ifdef CONFIG_GENERIC_PENDING_IRQ
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set_pending_irq(irq, cpumask);
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#else
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desc->affinity = cpumask;
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desc->chip->set_affinity(irq, cpumask);
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#endif
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return 0;
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}
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#endif
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/**
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* disable_irq_nosync - disable an irq without waiting
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* @irq: Interrupt to disable
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*
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* Disable the selected interrupt line. Disables and Enables are
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* nested.
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* Unlike disable_irq(), this function does not ensure existing
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* instances of the IRQ handler have completed before returning.
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*
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* This function may be called from IRQ context.
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*/
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void disable_irq_nosync(unsigned int irq)
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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)
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return;
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spin_lock_irqsave(&desc->lock, flags);
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if (!desc->depth++) {
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desc->status |= IRQ_DISABLED;
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desc->chip->disable(irq);
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}
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spin_unlock_irqrestore(&desc->lock, flags);
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}
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EXPORT_SYMBOL(disable_irq_nosync);
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/**
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* disable_irq - disable an irq and wait for completion
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* @irq: Interrupt to disable
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*
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* Disable the selected interrupt line. Enables and Disables are
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* nested.
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* This function waits for any pending IRQ handlers for this interrupt
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* to complete before returning. If you use this function while
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* holding a resource the IRQ handler may need you will deadlock.
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*
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* This function may be called - with care - from IRQ context.
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*/
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void disable_irq(unsigned int irq)
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{
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struct irq_desc *desc = irq_desc + irq;
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if (irq >= NR_IRQS)
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return;
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disable_irq_nosync(irq);
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if (desc->action)
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synchronize_irq(irq);
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}
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EXPORT_SYMBOL(disable_irq);
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/**
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* enable_irq - enable handling of an irq
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* @irq: Interrupt to enable
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*
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* Undoes the effect of one call to disable_irq(). If this
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* matches the last disable, processing of interrupts on this
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* IRQ line is re-enabled.
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*
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* This function may be called from IRQ context.
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*/
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void enable_irq(unsigned int irq)
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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)
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return;
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spin_lock_irqsave(&desc->lock, flags);
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switch (desc->depth) {
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case 0:
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printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
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WARN_ON(1);
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break;
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case 1: {
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unsigned int status = desc->status & ~IRQ_DISABLED;
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/* Prevent probing on this irq: */
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desc->status = status | IRQ_NOPROBE;
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check_irq_resend(desc, irq);
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/* fall-through */
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}
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default:
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desc->depth--;
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}
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spin_unlock_irqrestore(&desc->lock, flags);
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}
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EXPORT_SYMBOL(enable_irq);
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/**
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* set_irq_wake - control irq power management wakeup
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* @irq: interrupt to control
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* @on: enable/disable power management wakeup
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*
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* Enable/disable power management wakeup mode, which is
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* disabled by default. Enables and disables must match,
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* just as they match for non-wakeup mode support.
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*
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* Wakeup mode lets this IRQ wake the system from sleep
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* states like "suspend to RAM".
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*/
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int set_irq_wake(unsigned int irq, unsigned int on)
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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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int ret = -ENXIO;
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int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;
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/* wakeup-capable irqs can be shared between drivers that
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* don't need to have the same sleep mode behaviors.
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*/
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spin_lock_irqsave(&desc->lock, flags);
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if (on) {
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if (desc->wake_depth++ == 0)
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desc->status |= IRQ_WAKEUP;
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else
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set_wake = NULL;
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} else {
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if (desc->wake_depth == 0) {
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printk(KERN_WARNING "Unbalanced IRQ %d "
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"wake disable\n", irq);
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WARN_ON(1);
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} else if (--desc->wake_depth == 0)
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desc->status &= ~IRQ_WAKEUP;
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else
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set_wake = NULL;
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}
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if (set_wake)
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ret = desc->chip->set_wake(irq, on);
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spin_unlock_irqrestore(&desc->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL(set_irq_wake);
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/*
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* Internal function that tells the architecture code whether a
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* particular irq has been exclusively allocated or is available
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* for driver use.
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*/
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int can_request_irq(unsigned int irq, unsigned long irqflags)
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{
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struct irqaction *action;
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if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
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return 0;
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action = irq_desc[irq].action;
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if (action)
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if (irqflags & action->flags & IRQF_SHARED)
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action = NULL;
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return !action;
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}
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void compat_irq_chip_set_default_handler(struct irq_desc *desc)
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{
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/*
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* If the architecture still has not overriden
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* the flow handler then zap the default. This
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* should catch incorrect flow-type setting.
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*/
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if (desc->handle_irq == &handle_bad_irq)
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desc->handle_irq = NULL;
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}
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/*
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* Internal function to register an irqaction - typically used to
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* allocate special interrupts that are part of the architecture.
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*/
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int setup_irq(unsigned int irq, struct irqaction *new)
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{
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struct irq_desc *desc = irq_desc + irq;
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struct irqaction *old, **p;
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const char *old_name = NULL;
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unsigned long flags;
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int shared = 0;
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if (irq >= NR_IRQS)
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return -EINVAL;
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if (desc->chip == &no_irq_chip)
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return -ENOSYS;
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/*
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* Some drivers like serial.c use request_irq() heavily,
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* so we have to be careful not to interfere with a
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* running system.
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*/
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if (new->flags & IRQF_SAMPLE_RANDOM) {
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/*
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* This function might sleep, we want to call it first,
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* outside of the atomic block.
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* Yes, this might clear the entropy pool if the wrong
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* driver is attempted to be loaded, without actually
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* installing a new handler, but is this really a problem,
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* only the sysadmin is able to do this.
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*/
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rand_initialize_irq(irq);
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}
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/*
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* The following block of code has to be executed atomically
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*/
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spin_lock_irqsave(&desc->lock, flags);
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p = &desc->action;
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old = *p;
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if (old) {
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/*
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* Can't share interrupts unless both agree to and are
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* the same type (level, edge, polarity). So both flag
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* fields must have IRQF_SHARED set and the bits which
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* set the trigger type must match.
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*/
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if (!((old->flags & new->flags) & IRQF_SHARED) ||
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((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
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old_name = old->name;
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goto mismatch;
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}
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#if defined(CONFIG_IRQ_PER_CPU)
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/* All handlers must agree on per-cpuness */
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if ((old->flags & IRQF_PERCPU) !=
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(new->flags & IRQF_PERCPU))
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goto mismatch;
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#endif
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/* add new interrupt at end of irq queue */
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do {
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p = &old->next;
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old = *p;
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} while (old);
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shared = 1;
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}
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*p = new;
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/* Exclude IRQ from balancing */
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if (new->flags & IRQF_NOBALANCING)
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desc->status |= IRQ_NO_BALANCING;
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if (!shared) {
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irq_chip_set_defaults(desc->chip);
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#if defined(CONFIG_IRQ_PER_CPU)
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if (new->flags & IRQF_PERCPU)
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desc->status |= IRQ_PER_CPU;
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#endif
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/* Setup the type (level, edge polarity) if configured: */
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if (new->flags & IRQF_TRIGGER_MASK) {
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if (desc->chip && desc->chip->set_type)
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desc->chip->set_type(irq,
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new->flags & IRQF_TRIGGER_MASK);
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else
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/*
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* IRQF_TRIGGER_* but the PIC does not support
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* multiple flow-types?
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*/
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printk(KERN_WARNING "No IRQF_TRIGGER set_type "
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"function for IRQ %d (%s)\n", irq,
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desc->chip ? desc->chip->name :
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"unknown");
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} else
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compat_irq_chip_set_default_handler(desc);
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desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
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IRQ_INPROGRESS);
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if (!(desc->status & IRQ_NOAUTOEN)) {
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desc->depth = 0;
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desc->status &= ~IRQ_DISABLED;
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if (desc->chip->startup)
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desc->chip->startup(irq);
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else
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desc->chip->enable(irq);
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} else
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/* Undo nested disables: */
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desc->depth = 1;
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}
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/* Reset broken irq detection when installing new handler */
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desc->irq_count = 0;
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desc->irqs_unhandled = 0;
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spin_unlock_irqrestore(&desc->lock, flags);
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new->irq = irq;
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register_irq_proc(irq);
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new->dir = NULL;
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register_handler_proc(irq, new);
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return 0;
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mismatch:
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#ifdef CONFIG_DEBUG_SHIRQ
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if (!(new->flags & IRQF_PROBE_SHARED)) {
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printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
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if (old_name)
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printk(KERN_ERR "current handler: %s\n", old_name);
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dump_stack();
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}
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#endif
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spin_unlock_irqrestore(&desc->lock, flags);
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return -EBUSY;
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}
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/**
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* free_irq - free an interrupt
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* @irq: Interrupt line to free
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* @dev_id: Device identity to free
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*
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* Remove an interrupt handler. The handler is removed and if the
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* interrupt line is no longer in use by any driver it is disabled.
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* On a shared IRQ the caller must ensure the interrupt is disabled
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* on the card it drives before calling this function. The function
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* does not return until any executing interrupts for this IRQ
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* have completed.
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*
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* This function must not be called from interrupt context.
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*/
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void free_irq(unsigned int irq, void *dev_id)
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{
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struct irq_desc *desc;
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struct irqaction **p;
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unsigned long flags;
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WARN_ON(in_interrupt());
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if (irq >= NR_IRQS)
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return;
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desc = irq_desc + irq;
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spin_lock_irqsave(&desc->lock, flags);
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p = &desc->action;
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for (;;) {
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struct irqaction *action = *p;
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if (action) {
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struct irqaction **pp = p;
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p = &action->next;
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if (action->dev_id != dev_id)
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continue;
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/* Found it - now remove it from the list of entries */
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*pp = action->next;
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/* Currently used only by UML, might disappear one day.*/
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#ifdef CONFIG_IRQ_RELEASE_METHOD
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if (desc->chip->release)
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desc->chip->release(irq, dev_id);
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#endif
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if (!desc->action) {
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desc->status |= IRQ_DISABLED;
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if (desc->chip->shutdown)
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desc->chip->shutdown(irq);
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else
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desc->chip->disable(irq);
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}
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spin_unlock_irqrestore(&desc->lock, flags);
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unregister_handler_proc(irq, action);
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/* Make sure it's not being used on another CPU */
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synchronize_irq(irq);
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#ifdef CONFIG_DEBUG_SHIRQ
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/*
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* It's a shared IRQ -- the driver ought to be
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* prepared for it to happen even now it's
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* being freed, so let's make sure.... We do
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* this after actually deregistering it, to
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* make sure that a 'real' IRQ doesn't run in
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* parallel with our fake
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*/
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if (action->flags & IRQF_SHARED) {
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local_irq_save(flags);
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action->handler(irq, dev_id);
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local_irq_restore(flags);
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}
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#endif
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kfree(action);
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return;
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}
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printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
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spin_unlock_irqrestore(&desc->lock, flags);
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return;
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}
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}
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EXPORT_SYMBOL(free_irq);
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/**
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* request_irq - allocate an interrupt line
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* @irq: Interrupt line to allocate
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* @handler: Function to be called when the IRQ occurs
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* @irqflags: Interrupt type flags
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* @devname: An ascii name for the claiming device
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* @dev_id: A cookie passed back to the handler function
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*
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* This call allocates interrupt resources and enables the
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* interrupt line and IRQ handling. From the point this
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* call is made your handler function may be invoked. Since
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* your handler function must clear any interrupt the board
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* raises, you must take care both to initialise your hardware
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* and to set up the interrupt handler in the right order.
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*
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* Dev_id must be globally unique. Normally the address of the
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* device data structure is used as the cookie. Since the handler
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* receives this value it makes sense to use it.
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*
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* If your interrupt is shared you must pass a non NULL dev_id
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* as this is required when freeing the interrupt.
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*
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* Flags:
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*
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* IRQF_SHARED Interrupt is shared
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* IRQF_DISABLED Disable local interrupts while processing
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* IRQF_SAMPLE_RANDOM The interrupt can be used for entropy
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*
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*/
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int request_irq(unsigned int irq, irq_handler_t handler,
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unsigned long irqflags, const char *devname, void *dev_id)
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{
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struct irqaction *action;
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int retval;
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#ifdef CONFIG_LOCKDEP
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/*
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* Lockdep wants atomic interrupt handlers:
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*/
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irqflags |= IRQF_DISABLED;
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#endif
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/*
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* Sanity-check: shared interrupts must pass in a real dev-ID,
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* otherwise we'll have trouble later trying to figure out
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|
* which interrupt is which (messes up the interrupt freeing
|
|
* logic etc).
|
|
*/
|
|
if ((irqflags & IRQF_SHARED) && !dev_id)
|
|
return -EINVAL;
|
|
if (irq >= NR_IRQS)
|
|
return -EINVAL;
|
|
if (irq_desc[irq].status & IRQ_NOREQUEST)
|
|
return -EINVAL;
|
|
if (!handler)
|
|
return -EINVAL;
|
|
|
|
action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
|
|
if (!action)
|
|
return -ENOMEM;
|
|
|
|
action->handler = handler;
|
|
action->flags = irqflags;
|
|
cpus_clear(action->mask);
|
|
action->name = devname;
|
|
action->next = NULL;
|
|
action->dev_id = dev_id;
|
|
|
|
select_smp_affinity(irq);
|
|
|
|
#ifdef CONFIG_DEBUG_SHIRQ
|
|
if (irqflags & IRQF_SHARED) {
|
|
/*
|
|
* It's a shared IRQ -- the driver ought to be prepared for it
|
|
* to happen immediately, so let's make sure....
|
|
* We do this before actually registering it, to make sure that
|
|
* a 'real' IRQ doesn't run in parallel with our fake
|
|
*/
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
handler(irq, dev_id);
|
|
local_irq_restore(flags);
|
|
}
|
|
#endif
|
|
|
|
retval = setup_irq(irq, action);
|
|
if (retval)
|
|
kfree(action);
|
|
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL(request_irq);
|