259 lines
6.3 KiB
C
259 lines
6.3 KiB
C
/*
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* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
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*
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* This file contains the lowest level x86-specific interrupt
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* entry, irq-stacks and irq statistics code. All the remaining
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* irq logic is done by the generic kernel/irq/ code and
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* by the x86-specific irq controller code. (e.g. i8259.c and
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* io_apic.c.)
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*/
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#include <linux/module.h>
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#include <linux/seq_file.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/delay.h>
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#include <linux/uaccess.h>
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#include <linux/percpu.h>
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#include <asm/apic.h>
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DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
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EXPORT_PER_CPU_SYMBOL(irq_stat);
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DEFINE_PER_CPU(struct pt_regs *, irq_regs);
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EXPORT_PER_CPU_SYMBOL(irq_regs);
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#ifdef CONFIG_DEBUG_STACKOVERFLOW
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/* Debugging check for stack overflow: is there less than 1KB free? */
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static int check_stack_overflow(void)
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{
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long sp;
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__asm__ __volatile__("andl %%esp,%0" :
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"=r" (sp) : "0" (THREAD_SIZE - 1));
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return sp < (sizeof(struct thread_info) + STACK_WARN);
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}
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static void print_stack_overflow(void)
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{
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printk(KERN_WARNING "low stack detected by irq handler\n");
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dump_stack();
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}
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#else
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static inline int check_stack_overflow(void) { return 0; }
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static inline void print_stack_overflow(void) { }
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#endif
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#ifdef CONFIG_4KSTACKS
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/*
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* per-CPU IRQ handling contexts (thread information and stack)
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*/
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union irq_ctx {
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struct thread_info tinfo;
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u32 stack[THREAD_SIZE/sizeof(u32)];
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} __attribute__((aligned(PAGE_SIZE)));
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static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
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static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
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static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, hardirq_stack);
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static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, softirq_stack);
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static void call_on_stack(void *func, void *stack)
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{
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asm volatile("xchgl %%ebx,%%esp \n"
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"call *%%edi \n"
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"movl %%ebx,%%esp \n"
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: "=b" (stack)
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: "0" (stack),
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"D"(func)
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: "memory", "cc", "edx", "ecx", "eax");
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}
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static inline int
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execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
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{
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union irq_ctx *curctx, *irqctx;
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u32 *isp, arg1, arg2;
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curctx = (union irq_ctx *) current_thread_info();
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irqctx = __get_cpu_var(hardirq_ctx);
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/*
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* this is where we switch to the IRQ stack. However, if we are
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* already using the IRQ stack (because we interrupted a hardirq
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* handler) we can't do that and just have to keep using the
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* current stack (which is the irq stack already after all)
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*/
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if (unlikely(curctx == irqctx))
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return 0;
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/* build the stack frame on the IRQ stack */
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isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
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irqctx->tinfo.task = curctx->tinfo.task;
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irqctx->tinfo.previous_esp = current_stack_pointer;
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/*
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* Copy the softirq bits in preempt_count so that the
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* softirq checks work in the hardirq context.
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*/
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irqctx->tinfo.preempt_count =
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(irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
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(curctx->tinfo.preempt_count & SOFTIRQ_MASK);
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if (unlikely(overflow))
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call_on_stack(print_stack_overflow, isp);
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asm volatile("xchgl %%ebx,%%esp \n"
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"call *%%edi \n"
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"movl %%ebx,%%esp \n"
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: "=a" (arg1), "=d" (arg2), "=b" (isp)
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: "0" (irq), "1" (desc), "2" (isp),
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"D" (desc->handle_irq)
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: "memory", "cc", "ecx");
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return 1;
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}
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/*
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* allocate per-cpu stacks for hardirq and for softirq processing
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*/
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void __cpuinit irq_ctx_init(int cpu)
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{
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union irq_ctx *irqctx;
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if (per_cpu(hardirq_ctx, cpu))
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return;
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irqctx = &per_cpu(hardirq_stack, cpu);
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irqctx->tinfo.task = NULL;
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irqctx->tinfo.exec_domain = NULL;
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irqctx->tinfo.cpu = cpu;
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irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
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irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
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per_cpu(hardirq_ctx, cpu) = irqctx;
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irqctx = &per_cpu(softirq_stack, cpu);
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irqctx->tinfo.task = NULL;
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irqctx->tinfo.exec_domain = NULL;
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irqctx->tinfo.cpu = cpu;
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irqctx->tinfo.preempt_count = 0;
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irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
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per_cpu(softirq_ctx, cpu) = irqctx;
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printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
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cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu));
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}
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void irq_ctx_exit(int cpu)
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{
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per_cpu(hardirq_ctx, cpu) = NULL;
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}
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asmlinkage void do_softirq(void)
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{
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unsigned long flags;
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struct thread_info *curctx;
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union irq_ctx *irqctx;
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u32 *isp;
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if (in_interrupt())
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return;
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local_irq_save(flags);
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if (local_softirq_pending()) {
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curctx = current_thread_info();
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irqctx = __get_cpu_var(softirq_ctx);
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irqctx->tinfo.task = curctx->task;
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irqctx->tinfo.previous_esp = current_stack_pointer;
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/* build the stack frame on the softirq stack */
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isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
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call_on_stack(__do_softirq, isp);
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/*
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* Shouldnt happen, we returned above if in_interrupt():
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*/
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WARN_ON_ONCE(softirq_count());
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}
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local_irq_restore(flags);
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}
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#else
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static inline int
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execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) { return 0; }
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#endif
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bool handle_irq(unsigned irq, struct pt_regs *regs)
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{
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struct irq_desc *desc;
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int overflow;
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overflow = check_stack_overflow();
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desc = irq_to_desc(irq);
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if (unlikely(!desc))
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return false;
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if (!execute_on_irq_stack(overflow, desc, irq)) {
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if (unlikely(overflow))
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print_stack_overflow();
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desc->handle_irq(irq, desc);
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}
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return true;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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/* A cpu has been removed from cpu_online_mask. Reset irq affinities. */
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void fixup_irqs(void)
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{
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unsigned int irq;
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static int warned;
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struct irq_desc *desc;
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for_each_irq_desc(irq, desc) {
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const struct cpumask *affinity;
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if (!desc)
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continue;
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if (irq == 2)
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continue;
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affinity = desc->affinity;
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if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
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printk("Breaking affinity for irq %i\n", irq);
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affinity = cpu_all_mask;
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}
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if (desc->chip->set_affinity)
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desc->chip->set_affinity(irq, affinity);
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else if (desc->action && !(warned++))
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printk("Cannot set affinity for irq %i\n", irq);
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}
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#if 0
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barrier();
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/* Ingo Molnar says: "after the IO-APIC masks have been redirected
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[note the nop - the interrupt-enable boundary on x86 is two
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instructions from sti] - to flush out pending hardirqs and
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IPIs. After this point nothing is supposed to reach this CPU." */
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__asm__ __volatile__("sti; nop; cli");
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barrier();
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#else
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/* That doesn't seem sufficient. Give it 1ms. */
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local_irq_enable();
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mdelay(1);
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local_irq_disable();
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#endif
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}
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#endif
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