95c354fe9f
The break_lock data structure and code for spinlocks is quite nasty. Not only does it double the size of a spinlock but it changes locking to a potentially less optimal trylock. Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a __raw_spin_is_contended that uses the lock data itself to determine whether there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is not set. Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to decouple it from the spinlock implementation, and make it typesafe (rwlocks do not have any need_lockbreak sites -- why do they even get bloated up with that break_lock then?). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
356 lines
11 KiB
C
356 lines
11 KiB
C
#ifndef __LINUX_SPINLOCK_H
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#define __LINUX_SPINLOCK_H
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/*
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* include/linux/spinlock.h - generic spinlock/rwlock declarations
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*
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* here's the role of the various spinlock/rwlock related include files:
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*
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* on SMP builds:
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*
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* asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
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* initializers
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*
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* linux/spinlock_types.h:
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* defines the generic type and initializers
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*
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* asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel
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* implementations, mostly inline assembly code
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*
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* (also included on UP-debug builds:)
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*
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* linux/spinlock_api_smp.h:
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* contains the prototypes for the _spin_*() APIs.
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*
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* linux/spinlock.h: builds the final spin_*() APIs.
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*
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* on UP builds:
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*
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* linux/spinlock_type_up.h:
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* contains the generic, simplified UP spinlock type.
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* (which is an empty structure on non-debug builds)
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*
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* linux/spinlock_types.h:
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* defines the generic type and initializers
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*
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* linux/spinlock_up.h:
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* contains the __raw_spin_*()/etc. version of UP
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* builds. (which are NOPs on non-debug, non-preempt
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* builds)
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*
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* (included on UP-non-debug builds:)
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*
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* linux/spinlock_api_up.h:
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* builds the _spin_*() APIs.
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*
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* linux/spinlock.h: builds the final spin_*() APIs.
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*/
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#include <linux/preempt.h>
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#include <linux/linkage.h>
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#include <linux/compiler.h>
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#include <linux/thread_info.h>
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#include <linux/kernel.h>
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#include <linux/stringify.h>
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#include <linux/bottom_half.h>
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#include <asm/system.h>
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/*
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* Must define these before including other files, inline functions need them
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*/
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#define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME
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#define LOCK_SECTION_START(extra) \
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".subsection 1\n\t" \
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extra \
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".ifndef " LOCK_SECTION_NAME "\n\t" \
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LOCK_SECTION_NAME ":\n\t" \
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".endif\n"
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#define LOCK_SECTION_END \
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".previous\n\t"
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#define __lockfunc fastcall __attribute__((section(".spinlock.text")))
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/*
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* Pull the raw_spinlock_t and raw_rwlock_t definitions:
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*/
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#include <linux/spinlock_types.h>
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extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
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/*
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* Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
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*/
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#ifdef CONFIG_SMP
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# include <asm/spinlock.h>
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#else
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# include <linux/spinlock_up.h>
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#endif
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#ifdef CONFIG_DEBUG_SPINLOCK
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extern void __spin_lock_init(spinlock_t *lock, const char *name,
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struct lock_class_key *key);
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# define spin_lock_init(lock) \
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do { \
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static struct lock_class_key __key; \
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\
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__spin_lock_init((lock), #lock, &__key); \
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} while (0)
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#else
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# define spin_lock_init(lock) \
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do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
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#endif
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#ifdef CONFIG_DEBUG_SPINLOCK
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extern void __rwlock_init(rwlock_t *lock, const char *name,
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struct lock_class_key *key);
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# define rwlock_init(lock) \
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do { \
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static struct lock_class_key __key; \
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\
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__rwlock_init((lock), #lock, &__key); \
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} while (0)
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#else
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# define rwlock_init(lock) \
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do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
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#endif
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#define spin_is_locked(lock) __raw_spin_is_locked(&(lock)->raw_lock)
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#ifdef CONFIG_GENERIC_LOCKBREAK
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#define spin_is_contended(lock) ((lock)->break_lock)
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#else
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#define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
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#endif
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/**
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* spin_unlock_wait - wait until the spinlock gets unlocked
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* @lock: the spinlock in question.
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*/
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#define spin_unlock_wait(lock) __raw_spin_unlock_wait(&(lock)->raw_lock)
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/*
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* Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
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*/
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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# include <linux/spinlock_api_smp.h>
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#else
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# include <linux/spinlock_api_up.h>
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#endif
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#ifdef CONFIG_DEBUG_SPINLOCK
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extern void _raw_spin_lock(spinlock_t *lock);
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#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
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extern int _raw_spin_trylock(spinlock_t *lock);
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extern void _raw_spin_unlock(spinlock_t *lock);
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extern void _raw_read_lock(rwlock_t *lock);
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extern int _raw_read_trylock(rwlock_t *lock);
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extern void _raw_read_unlock(rwlock_t *lock);
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extern void _raw_write_lock(rwlock_t *lock);
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extern int _raw_write_trylock(rwlock_t *lock);
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extern void _raw_write_unlock(rwlock_t *lock);
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#else
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# define _raw_spin_lock(lock) __raw_spin_lock(&(lock)->raw_lock)
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# define _raw_spin_lock_flags(lock, flags) \
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__raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
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# define _raw_spin_trylock(lock) __raw_spin_trylock(&(lock)->raw_lock)
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# define _raw_spin_unlock(lock) __raw_spin_unlock(&(lock)->raw_lock)
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# define _raw_read_lock(rwlock) __raw_read_lock(&(rwlock)->raw_lock)
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# define _raw_read_trylock(rwlock) __raw_read_trylock(&(rwlock)->raw_lock)
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# define _raw_read_unlock(rwlock) __raw_read_unlock(&(rwlock)->raw_lock)
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# define _raw_write_lock(rwlock) __raw_write_lock(&(rwlock)->raw_lock)
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# define _raw_write_trylock(rwlock) __raw_write_trylock(&(rwlock)->raw_lock)
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# define _raw_write_unlock(rwlock) __raw_write_unlock(&(rwlock)->raw_lock)
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#endif
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#define read_can_lock(rwlock) __raw_read_can_lock(&(rwlock)->raw_lock)
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#define write_can_lock(rwlock) __raw_write_can_lock(&(rwlock)->raw_lock)
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/*
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* Define the various spin_lock and rw_lock methods. Note we define these
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* regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
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* methods are defined as nops in the case they are not required.
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*/
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#define spin_trylock(lock) __cond_lock(lock, _spin_trylock(lock))
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#define read_trylock(lock) __cond_lock(lock, _read_trylock(lock))
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#define write_trylock(lock) __cond_lock(lock, _write_trylock(lock))
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#define spin_lock(lock) _spin_lock(lock)
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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# define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
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#else
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# define spin_lock_nested(lock, subclass) _spin_lock(lock)
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#endif
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#define write_lock(lock) _write_lock(lock)
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#define read_lock(lock) _read_lock(lock)
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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#define spin_lock_irqsave(lock, flags) flags = _spin_lock_irqsave(lock)
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#define read_lock_irqsave(lock, flags) flags = _read_lock_irqsave(lock)
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#define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define spin_lock_irqsave_nested(lock, flags, subclass) \
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flags = _spin_lock_irqsave_nested(lock, subclass)
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#else
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#define spin_lock_irqsave_nested(lock, flags, subclass) \
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flags = _spin_lock_irqsave(lock)
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#endif
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#else
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#define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
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#define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
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#define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
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#define spin_lock_irqsave_nested(lock, flags, subclass) \
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spin_lock_irqsave(lock, flags)
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#endif
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#define spin_lock_irq(lock) _spin_lock_irq(lock)
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#define spin_lock_bh(lock) _spin_lock_bh(lock)
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#define read_lock_irq(lock) _read_lock_irq(lock)
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#define read_lock_bh(lock) _read_lock_bh(lock)
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#define write_lock_irq(lock) _write_lock_irq(lock)
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#define write_lock_bh(lock) _write_lock_bh(lock)
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/*
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* We inline the unlock functions in the nondebug case:
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*/
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#if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
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!defined(CONFIG_SMP)
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# define spin_unlock(lock) _spin_unlock(lock)
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# define read_unlock(lock) _read_unlock(lock)
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# define write_unlock(lock) _write_unlock(lock)
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# define spin_unlock_irq(lock) _spin_unlock_irq(lock)
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# define read_unlock_irq(lock) _read_unlock_irq(lock)
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# define write_unlock_irq(lock) _write_unlock_irq(lock)
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#else
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# define spin_unlock(lock) \
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do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
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# define read_unlock(lock) \
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do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
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# define write_unlock(lock) \
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do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
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# define spin_unlock_irq(lock) \
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do { \
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__raw_spin_unlock(&(lock)->raw_lock); \
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__release(lock); \
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local_irq_enable(); \
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} while (0)
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# define read_unlock_irq(lock) \
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do { \
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__raw_read_unlock(&(lock)->raw_lock); \
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__release(lock); \
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local_irq_enable(); \
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} while (0)
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# define write_unlock_irq(lock) \
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do { \
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__raw_write_unlock(&(lock)->raw_lock); \
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__release(lock); \
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local_irq_enable(); \
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} while (0)
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#endif
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#define spin_unlock_irqrestore(lock, flags) \
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_spin_unlock_irqrestore(lock, flags)
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#define spin_unlock_bh(lock) _spin_unlock_bh(lock)
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#define read_unlock_irqrestore(lock, flags) \
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_read_unlock_irqrestore(lock, flags)
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#define read_unlock_bh(lock) _read_unlock_bh(lock)
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#define write_unlock_irqrestore(lock, flags) \
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_write_unlock_irqrestore(lock, flags)
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#define write_unlock_bh(lock) _write_unlock_bh(lock)
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#define spin_trylock_bh(lock) __cond_lock(lock, _spin_trylock_bh(lock))
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#define spin_trylock_irq(lock) \
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({ \
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local_irq_disable(); \
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spin_trylock(lock) ? \
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1 : ({ local_irq_enable(); 0; }); \
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})
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#define spin_trylock_irqsave(lock, flags) \
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({ \
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local_irq_save(flags); \
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spin_trylock(lock) ? \
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1 : ({ local_irq_restore(flags); 0; }); \
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})
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#define write_trylock_irqsave(lock, flags) \
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({ \
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local_irq_save(flags); \
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write_trylock(lock) ? \
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1 : ({ local_irq_restore(flags); 0; }); \
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})
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/*
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* Locks two spinlocks l1 and l2.
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* l1_first indicates if spinlock l1 should be taken first.
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*/
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static inline void double_spin_lock(spinlock_t *l1, spinlock_t *l2,
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bool l1_first)
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__acquires(l1)
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__acquires(l2)
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{
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if (l1_first) {
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spin_lock(l1);
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spin_lock(l2);
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} else {
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spin_lock(l2);
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spin_lock(l1);
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}
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}
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/*
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* Unlocks two spinlocks l1 and l2.
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* l1_taken_first indicates if spinlock l1 was taken first and therefore
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* should be released after spinlock l2.
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*/
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static inline void double_spin_unlock(spinlock_t *l1, spinlock_t *l2,
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bool l1_taken_first)
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__releases(l1)
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__releases(l2)
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{
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if (l1_taken_first) {
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spin_unlock(l2);
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spin_unlock(l1);
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} else {
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spin_unlock(l1);
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spin_unlock(l2);
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}
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}
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/*
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* Pull the atomic_t declaration:
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* (asm-mips/atomic.h needs above definitions)
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*/
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#include <asm/atomic.h>
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/**
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* atomic_dec_and_lock - lock on reaching reference count zero
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* @atomic: the atomic counter
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* @lock: the spinlock in question
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*/
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extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
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#define atomic_dec_and_lock(atomic, lock) \
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__cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
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/**
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* spin_can_lock - would spin_trylock() succeed?
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* @lock: the spinlock in question.
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*/
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#define spin_can_lock(lock) (!spin_is_locked(lock))
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#endif /* __LINUX_SPINLOCK_H */
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