mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 06:46:59 +07:00
c2d727aa2f
This patch makes RCU use softirq instead of tasklets. It also adds a memory barrier after raising the softirq inorder to ensure that the cpu sees the most recently updated value of rcu->cur while processing callbacks. The discussion of the related theoretical race pointed out by James Huang can be found here --> http://lkml.org/lkml/2007/11/20/603 Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Reviewed-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
448 lines
13 KiB
C
448 lines
13 KiB
C
/* interrupt.h */
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#ifndef _LINUX_INTERRUPT_H
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#define _LINUX_INTERRUPT_H
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#include <linux/kernel.h>
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#include <linux/linkage.h>
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#include <linux/bitops.h>
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#include <linux/preempt.h>
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#include <linux/cpumask.h>
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#include <linux/irqreturn.h>
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#include <linux/hardirq.h>
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#include <linux/sched.h>
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#include <linux/irqflags.h>
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#include <asm/atomic.h>
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#include <asm/ptrace.h>
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#include <asm/system.h>
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/*
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* These correspond to the IORESOURCE_IRQ_* defines in
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* linux/ioport.h to select the interrupt line behaviour. When
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* requesting an interrupt without specifying a IRQF_TRIGGER, the
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* setting should be assumed to be "as already configured", which
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* may be as per machine or firmware initialisation.
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*/
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#define IRQF_TRIGGER_NONE 0x00000000
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#define IRQF_TRIGGER_RISING 0x00000001
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#define IRQF_TRIGGER_FALLING 0x00000002
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#define IRQF_TRIGGER_HIGH 0x00000004
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#define IRQF_TRIGGER_LOW 0x00000008
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#define IRQF_TRIGGER_MASK (IRQF_TRIGGER_HIGH | IRQF_TRIGGER_LOW | \
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)
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#define IRQF_TRIGGER_PROBE 0x00000010
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/*
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* These flags used only by the kernel as part of the
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* irq handling routines.
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*
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* IRQF_DISABLED - keep irqs disabled when calling the action handler
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* IRQF_SAMPLE_RANDOM - irq is used to feed the random generator
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* IRQF_SHARED - allow sharing the irq among several devices
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* IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
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* IRQF_TIMER - Flag to mark this interrupt as timer interrupt
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* IRQF_PERCPU - Interrupt is per cpu
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* IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
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* IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
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* registered first in an shared interrupt is considered for
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* performance reasons)
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*/
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#define IRQF_DISABLED 0x00000020
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#define IRQF_SAMPLE_RANDOM 0x00000040
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#define IRQF_SHARED 0x00000080
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#define IRQF_PROBE_SHARED 0x00000100
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#define IRQF_TIMER 0x00000200
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#define IRQF_PERCPU 0x00000400
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#define IRQF_NOBALANCING 0x00000800
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#define IRQF_IRQPOLL 0x00001000
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typedef irqreturn_t (*irq_handler_t)(int, void *);
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struct irqaction {
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irq_handler_t handler;
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unsigned long flags;
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cpumask_t mask;
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const char *name;
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void *dev_id;
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struct irqaction *next;
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int irq;
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struct proc_dir_entry *dir;
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};
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extern irqreturn_t no_action(int cpl, void *dev_id);
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extern int __must_check request_irq(unsigned int, irq_handler_t handler,
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unsigned long, const char *, void *);
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extern void free_irq(unsigned int, void *);
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struct device;
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extern int __must_check devm_request_irq(struct device *dev, unsigned int irq,
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irq_handler_t handler, unsigned long irqflags,
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const char *devname, void *dev_id);
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extern void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id);
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/*
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* On lockdep we dont want to enable hardirqs in hardirq
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* context. Use local_irq_enable_in_hardirq() to annotate
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* kernel code that has to do this nevertheless (pretty much
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* the only valid case is for old/broken hardware that is
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* insanely slow).
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*
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* NOTE: in theory this might break fragile code that relies
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* on hardirq delivery - in practice we dont seem to have such
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* places left. So the only effect should be slightly increased
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* irqs-off latencies.
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*/
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#ifdef CONFIG_LOCKDEP
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# define local_irq_enable_in_hardirq() do { } while (0)
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#else
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# define local_irq_enable_in_hardirq() local_irq_enable()
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#endif
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extern void disable_irq_nosync(unsigned int irq);
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extern void disable_irq(unsigned int irq);
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extern void enable_irq(unsigned int irq);
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#ifdef CONFIG_GENERIC_HARDIRQS
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/*
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* Special lockdep variants of irq disabling/enabling.
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* These should be used for locking constructs that
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* know that a particular irq context which is disabled,
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* and which is the only irq-context user of a lock,
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* that it's safe to take the lock in the irq-disabled
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* section without disabling hardirqs.
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*
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* On !CONFIG_LOCKDEP they are equivalent to the normal
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* irq disable/enable methods.
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*/
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static inline void disable_irq_nosync_lockdep(unsigned int irq)
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{
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disable_irq_nosync(irq);
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#ifdef CONFIG_LOCKDEP
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local_irq_disable();
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#endif
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}
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static inline void disable_irq_nosync_lockdep_irqsave(unsigned int irq, unsigned long *flags)
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{
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disable_irq_nosync(irq);
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#ifdef CONFIG_LOCKDEP
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local_irq_save(*flags);
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#endif
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}
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static inline void disable_irq_lockdep(unsigned int irq)
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{
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disable_irq(irq);
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#ifdef CONFIG_LOCKDEP
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local_irq_disable();
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#endif
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}
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static inline void enable_irq_lockdep(unsigned int irq)
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{
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#ifdef CONFIG_LOCKDEP
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local_irq_enable();
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#endif
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enable_irq(irq);
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}
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static inline void enable_irq_lockdep_irqrestore(unsigned int irq, unsigned long *flags)
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{
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#ifdef CONFIG_LOCKDEP
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local_irq_restore(*flags);
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#endif
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enable_irq(irq);
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}
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/* IRQ wakeup (PM) control: */
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extern int set_irq_wake(unsigned int irq, unsigned int on);
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static inline int enable_irq_wake(unsigned int irq)
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{
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return set_irq_wake(irq, 1);
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}
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static inline int disable_irq_wake(unsigned int irq)
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{
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return set_irq_wake(irq, 0);
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}
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#else /* !CONFIG_GENERIC_HARDIRQS */
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/*
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* NOTE: non-genirq architectures, if they want to support the lock
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* validator need to define the methods below in their asm/irq.h
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* files, under an #ifdef CONFIG_LOCKDEP section.
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*/
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#ifndef CONFIG_LOCKDEP
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# define disable_irq_nosync_lockdep(irq) disable_irq_nosync(irq)
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# define disable_irq_nosync_lockdep_irqsave(irq, flags) \
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disable_irq_nosync(irq)
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# define disable_irq_lockdep(irq) disable_irq(irq)
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# define enable_irq_lockdep(irq) enable_irq(irq)
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# define enable_irq_lockdep_irqrestore(irq, flags) \
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enable_irq(irq)
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# endif
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static inline int enable_irq_wake(unsigned int irq)
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{
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return 0;
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}
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static inline int disable_irq_wake(unsigned int irq)
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{
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return 0;
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}
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#endif /* CONFIG_GENERIC_HARDIRQS */
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#ifndef __ARCH_SET_SOFTIRQ_PENDING
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#define set_softirq_pending(x) (local_softirq_pending() = (x))
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#define or_softirq_pending(x) (local_softirq_pending() |= (x))
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#endif
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/*
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* Temporary defines for UP kernels, until all code gets fixed.
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*/
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#ifndef CONFIG_SMP
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static inline void __deprecated cli(void)
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{
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local_irq_disable();
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}
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static inline void __deprecated sti(void)
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{
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local_irq_enable();
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}
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static inline void __deprecated save_flags(unsigned long *x)
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{
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local_save_flags(*x);
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}
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#define save_flags(x) save_flags(&x)
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static inline void __deprecated restore_flags(unsigned long x)
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{
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local_irq_restore(x);
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}
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static inline void __deprecated save_and_cli(unsigned long *x)
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{
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local_irq_save(*x);
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}
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#define save_and_cli(x) save_and_cli(&x)
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#endif /* CONFIG_SMP */
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/* Some architectures might implement lazy enabling/disabling of
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* interrupts. In some cases, such as stop_machine, we might want
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* to ensure that after a local_irq_disable(), interrupts have
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* really been disabled in hardware. Such architectures need to
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* implement the following hook.
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*/
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#ifndef hard_irq_disable
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#define hard_irq_disable() do { } while(0)
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#endif
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/* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
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frequency threaded job scheduling. For almost all the purposes
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tasklets are more than enough. F.e. all serial device BHs et
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al. should be converted to tasklets, not to softirqs.
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*/
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enum
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{
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HI_SOFTIRQ=0,
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TIMER_SOFTIRQ,
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NET_TX_SOFTIRQ,
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NET_RX_SOFTIRQ,
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BLOCK_SOFTIRQ,
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TASKLET_SOFTIRQ,
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SCHED_SOFTIRQ,
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#ifdef CONFIG_HIGH_RES_TIMERS
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HRTIMER_SOFTIRQ,
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#endif
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RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */
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};
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/* softirq mask and active fields moved to irq_cpustat_t in
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* asm/hardirq.h to get better cache usage. KAO
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*/
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struct softirq_action
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{
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void (*action)(struct softirq_action *);
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void *data;
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};
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asmlinkage void do_softirq(void);
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extern void open_softirq(int nr, void (*action)(struct softirq_action*), void *data);
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extern void softirq_init(void);
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#define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
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extern void FASTCALL(raise_softirq_irqoff(unsigned int nr));
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extern void FASTCALL(raise_softirq(unsigned int nr));
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/* Tasklets --- multithreaded analogue of BHs.
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Main feature differing them of generic softirqs: tasklet
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is running only on one CPU simultaneously.
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Main feature differing them of BHs: different tasklets
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may be run simultaneously on different CPUs.
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Properties:
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* If tasklet_schedule() is called, then tasklet is guaranteed
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to be executed on some cpu at least once after this.
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* If the tasklet is already scheduled, but its excecution is still not
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started, it will be executed only once.
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* If this tasklet is already running on another CPU (or schedule is called
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from tasklet itself), it is rescheduled for later.
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* Tasklet is strictly serialized wrt itself, but not
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wrt another tasklets. If client needs some intertask synchronization,
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he makes it with spinlocks.
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*/
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struct tasklet_struct
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{
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struct tasklet_struct *next;
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unsigned long state;
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atomic_t count;
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void (*func)(unsigned long);
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unsigned long data;
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};
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#define DECLARE_TASKLET(name, func, data) \
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struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
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#define DECLARE_TASKLET_DISABLED(name, func, data) \
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struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
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enum
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{
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TASKLET_STATE_SCHED, /* Tasklet is scheduled for execution */
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TASKLET_STATE_RUN /* Tasklet is running (SMP only) */
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};
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#ifdef CONFIG_SMP
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static inline int tasklet_trylock(struct tasklet_struct *t)
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{
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return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
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}
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static inline void tasklet_unlock(struct tasklet_struct *t)
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{
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smp_mb__before_clear_bit();
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clear_bit(TASKLET_STATE_RUN, &(t)->state);
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}
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static inline void tasklet_unlock_wait(struct tasklet_struct *t)
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{
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while (test_bit(TASKLET_STATE_RUN, &(t)->state)) { barrier(); }
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}
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#else
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#define tasklet_trylock(t) 1
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#define tasklet_unlock_wait(t) do { } while (0)
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#define tasklet_unlock(t) do { } while (0)
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#endif
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extern void FASTCALL(__tasklet_schedule(struct tasklet_struct *t));
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static inline void tasklet_schedule(struct tasklet_struct *t)
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{
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if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
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__tasklet_schedule(t);
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}
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extern void FASTCALL(__tasklet_hi_schedule(struct tasklet_struct *t));
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static inline void tasklet_hi_schedule(struct tasklet_struct *t)
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{
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if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state))
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__tasklet_hi_schedule(t);
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}
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static inline void tasklet_disable_nosync(struct tasklet_struct *t)
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{
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atomic_inc(&t->count);
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smp_mb__after_atomic_inc();
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}
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static inline void tasklet_disable(struct tasklet_struct *t)
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{
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tasklet_disable_nosync(t);
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tasklet_unlock_wait(t);
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smp_mb();
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}
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static inline void tasklet_enable(struct tasklet_struct *t)
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{
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smp_mb__before_atomic_dec();
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atomic_dec(&t->count);
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}
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static inline void tasklet_hi_enable(struct tasklet_struct *t)
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{
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smp_mb__before_atomic_dec();
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atomic_dec(&t->count);
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}
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extern void tasklet_kill(struct tasklet_struct *t);
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extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
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extern void tasklet_init(struct tasklet_struct *t,
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void (*func)(unsigned long), unsigned long data);
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/*
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* Autoprobing for irqs:
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*
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* probe_irq_on() and probe_irq_off() provide robust primitives
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* for accurate IRQ probing during kernel initialization. They are
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* reasonably simple to use, are not "fooled" by spurious interrupts,
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* and, unlike other attempts at IRQ probing, they do not get hung on
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* stuck interrupts (such as unused PS2 mouse interfaces on ASUS boards).
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*
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* For reasonably foolproof probing, use them as follows:
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*
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* 1. clear and/or mask the device's internal interrupt.
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* 2. sti();
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* 3. irqs = probe_irq_on(); // "take over" all unassigned idle IRQs
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* 4. enable the device and cause it to trigger an interrupt.
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* 5. wait for the device to interrupt, using non-intrusive polling or a delay.
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* 6. irq = probe_irq_off(irqs); // get IRQ number, 0=none, negative=multiple
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* 7. service the device to clear its pending interrupt.
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* 8. loop again if paranoia is required.
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*
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* probe_irq_on() returns a mask of allocated irq's.
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*
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* probe_irq_off() takes the mask as a parameter,
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* and returns the irq number which occurred,
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* or zero if none occurred, or a negative irq number
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* if more than one irq occurred.
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*/
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#if defined(CONFIG_GENERIC_HARDIRQS) && !defined(CONFIG_GENERIC_IRQ_PROBE)
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static inline unsigned long probe_irq_on(void)
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{
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return 0;
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}
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static inline int probe_irq_off(unsigned long val)
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{
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return 0;
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}
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static inline unsigned int probe_irq_mask(unsigned long val)
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{
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return 0;
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}
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#else
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extern unsigned long probe_irq_on(void); /* returns 0 on failure */
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extern int probe_irq_off(unsigned long); /* returns 0 or negative on failure */
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extern unsigned int probe_irq_mask(unsigned long); /* returns mask of ISA interrupts */
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#endif
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#ifdef CONFIG_PROC_FS
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/* Initialize /proc/irq/ */
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extern void init_irq_proc(void);
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#else
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static inline void init_irq_proc(void)
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{
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}
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#endif
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#endif
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