[linux.git] / include / linux / spinlock.h

#ifndef __LINUX_SPINLOCK_H
#define __LINUX_SPINLOCK_H

/*
 * include/linux/spinlock.h - generic spinlock/rwlock declarations
 *
 * here's the role of the various spinlock/rwlock related include files:
 *
 * on SMP builds:
 *
 *  asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
 *                        initializers
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  asm/spinlock.h:       contains the __raw_spin_*()/etc. lowlevel
 *                        implementations, mostly inline assembly code
 *
 *   (also included on UP-debug builds:)
 *
 *  linux/spinlock_api_smp.h:
 *                        contains the prototypes for the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 *
 * on UP builds:
 *
 *  linux/spinlock_type_up.h:
 *                        contains the generic, simplified UP spinlock type.
 *                        (which is an empty structure on non-debug builds)
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  linux/spinlock_up.h:
 *                        contains the __raw_spin_*()/etc. version of UP
 *                        builds. (which are NOPs on non-debug, non-preempt
 *                        builds)
 *
 *   (included on UP-non-debug builds:)
 *
 *  linux/spinlock_api_up.h:
 *                        builds the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 */

#include <linux/preempt.h>
#include <linux/linkage.h>
#include <linux/compiler.h>
#include <linux/thread_info.h>
#include <linux/kernel.h>
#include <linux/stringify.h>

#include <asm/system.h>

/*
 * Must define these before including other files, inline functions need them
 */
#define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME

#define LOCK_SECTION_START(extra)               \
        ".subsection 1\n\t"                     \
        extra                                   \
        ".ifndef " LOCK_SECTION_NAME "\n\t"     \
        LOCK_SECTION_NAME ":\n\t"               \
        ".endif\n"

#define LOCK_SECTION_END                        \
        ".previous\n\t"

#define __lockfunc fastcall __attribute__((section(".spinlock.text")))

/*
 * Pull the raw_spinlock_t and raw_rwlock_t definitions:
 */
#include <linux/spinlock_types.h>

extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);

/*
 * Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
 */
#ifdef CONFIG_SMP
# include <asm/spinlock.h>
#else
# include <linux/spinlock_up.h>
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
  extern void __spin_lock_init(spinlock_t *lock, const char *name,
			       struct lock_class_key *key);
# define spin_lock_init(lock)					\
do {								\
	static struct lock_class_key __key;			\
								\
	__spin_lock_init((lock), #lock, &__key);		\
} while (0)

#else
# define spin_lock_init(lock)					\
	do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
  extern void __rwlock_init(rwlock_t *lock, const char *name,
			    struct lock_class_key *key);
# define rwlock_init(lock)					\
do {								\
	static struct lock_class_key __key;			\
								\
	__rwlock_init((lock), #lock, &__key);			\
} while (0)
#else
# define rwlock_init(lock)					\
	do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
#endif

#define spin_is_locked(lock)	__raw_spin_is_locked(&(lock)->raw_lock)

/**
 * spin_unlock_wait - wait until the spinlock gets unlocked
 * @lock: the spinlock in question.
 */
#define spin_unlock_wait(lock)	__raw_spin_unlock_wait(&(lock)->raw_lock)

/*
 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 */
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
# include <linux/spinlock_api_smp.h>
#else
# include <linux/spinlock_api_up.h>
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
 extern void _raw_spin_lock(spinlock_t *lock);
#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
 extern int _raw_spin_trylock(spinlock_t *lock);
 extern void _raw_spin_unlock(spinlock_t *lock);
 extern void _raw_read_lock(rwlock_t *lock);
 extern int _raw_read_trylock(rwlock_t *lock);
 extern void _raw_read_unlock(rwlock_t *lock);
 extern void _raw_write_lock(rwlock_t *lock);
 extern int _raw_write_trylock(rwlock_t *lock);
 extern void _raw_write_unlock(rwlock_t *lock);
#else
# define _raw_spin_lock(lock)		__raw_spin_lock(&(lock)->raw_lock)
# define _raw_spin_lock_flags(lock, flags) \
		__raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
# define _raw_spin_trylock(lock)	__raw_spin_trylock(&(lock)->raw_lock)
# define _raw_spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
# define _raw_read_lock(rwlock)		__raw_read_lock(&(rwlock)->raw_lock)
# define _raw_read_trylock(rwlock)	__raw_read_trylock(&(rwlock)->raw_lock)
# define _raw_read_unlock(rwlock)	__raw_read_unlock(&(rwlock)->raw_lock)
# define _raw_write_lock(rwlock)	__raw_write_lock(&(rwlock)->raw_lock)
# define _raw_write_trylock(rwlock)	__raw_write_trylock(&(rwlock)->raw_lock)
# define _raw_write_unlock(rwlock)	__raw_write_unlock(&(rwlock)->raw_lock)
#endif

#define read_can_lock(rwlock)		__raw_read_can_lock(&(rwlock)->raw_lock)
#define write_can_lock(rwlock)		__raw_write_can_lock(&(rwlock)->raw_lock)

/*
 * Define the various spin_lock and rw_lock methods.  Note we define these
 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 * methods are defined as nops in the case they are not required.
 */
#define spin_trylock(lock)		__cond_lock(_spin_trylock(lock))
#define read_trylock(lock)		__cond_lock(_read_trylock(lock))
#define write_trylock(lock)		__cond_lock(_write_trylock(lock))

#define spin_lock(lock)			_spin_lock(lock)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
#else
# define spin_lock_nested(lock, subclass) _spin_lock(lock)
#endif

#define write_lock(lock)		_write_lock(lock)
#define read_lock(lock)			_read_lock(lock)

#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
#define spin_lock_irqsave(lock, flags)	flags = _spin_lock_irqsave(lock)
#define read_lock_irqsave(lock, flags)	flags = _read_lock_irqsave(lock)
#define write_lock_irqsave(lock, flags)	flags = _write_lock_irqsave(lock)
#else
#define spin_lock_irqsave(lock, flags)	_spin_lock_irqsave(lock, flags)
#define read_lock_irqsave(lock, flags)	_read_lock_irqsave(lock, flags)
#define write_lock_irqsave(lock, flags)	_write_lock_irqsave(lock, flags)
#endif

#define spin_lock_irq(lock)		_spin_lock_irq(lock)
#define spin_lock_bh(lock)		_spin_lock_bh(lock)

#define read_lock_irq(lock)		_read_lock_irq(lock)
#define read_lock_bh(lock)		_read_lock_bh(lock)

#define write_lock_irq(lock)		_write_lock_irq(lock)
#define write_lock_bh(lock)		_write_lock_bh(lock)

/*
 * We inline the unlock functions in the nondebug case:
 */
#if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
	!defined(CONFIG_SMP)
# define spin_unlock(lock)		_spin_unlock(lock)
# define read_unlock(lock)		_read_unlock(lock)
# define write_unlock(lock)		_write_unlock(lock)
# define spin_unlock_irq(lock)		_spin_unlock_irq(lock)
# define read_unlock_irq(lock)		_read_unlock_irq(lock)
# define write_unlock_irq(lock)		_write_unlock_irq(lock)
#else
# define spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
# define read_unlock(lock)		__raw_read_unlock(&(lock)->raw_lock)
# define write_unlock(lock)		__raw_write_unlock(&(lock)->raw_lock)
# define spin_unlock_irq(lock) \
    do { __raw_spin_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
# define read_unlock_irq(lock) \
    do { __raw_read_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
# define write_unlock_irq(lock) \
    do { __raw_write_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
#endif

#define spin_unlock_irqrestore(lock, flags) \
					_spin_unlock_irqrestore(lock, flags)
#define spin_unlock_bh(lock)		_spin_unlock_bh(lock)

#define read_unlock_irqrestore(lock, flags) \
					_read_unlock_irqrestore(lock, flags)
#define read_unlock_bh(lock)		_read_unlock_bh(lock)

#define write_unlock_irqrestore(lock, flags) \
					_write_unlock_irqrestore(lock, flags)
#define write_unlock_bh(lock)		_write_unlock_bh(lock)

#define spin_trylock_bh(lock)		__cond_lock(_spin_trylock_bh(lock))

#define spin_trylock_irq(lock) \
({ \
	local_irq_disable(); \
	_spin_trylock(lock) ? \
	1 : ({ local_irq_enable(); 0;  }); \
})

#define spin_trylock_irqsave(lock, flags) \
({ \
	local_irq_save(flags); \
	_spin_trylock(lock) ? \
	1 : ({ local_irq_restore(flags); 0; }); \
})

/*
 * Pull the atomic_t declaration:
 * (asm-mips/atomic.h needs above definitions)
 */
#include <asm/atomic.h>
/**
 * atomic_dec_and_lock - lock on reaching reference count zero
 * @atomic: the atomic counter
 * @lock: the spinlock in question
 */
extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
#define atomic_dec_and_lock(atomic, lock) \
		__cond_lock(_atomic_dec_and_lock(atomic, lock))

/**
 * spin_can_lock - would spin_trylock() succeed?
 * @lock: the spinlock in question.
 */
#define spin_can_lock(lock)	(!spin_is_locked(lock))

#endif /* __LINUX_SPINLOCK_H */
Commit	Line	Data
1da177e4 LT	1	#ifndef __LINUX_SPINLOCK_H
	2	#define __LINUX_SPINLOCK_H
	3
	4	/*
fb1c8f93 IM	5	* include/linux/spinlock.h - generic spinlock/rwlock declarations
	6	*
	7	* here's the role of the various spinlock/rwlock related include files:
	8	*
	9	* on SMP builds:
	10	*
	11	* asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
	12	* initializers
	13	*
	14	* linux/spinlock_types.h:
	15	* defines the generic type and initializers
	16	*
	17	* asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel
	18	* implementations, mostly inline assembly code
	19	*
	20	* (also included on UP-debug builds:)
	21	*
	22	* linux/spinlock_api_smp.h:
	23	* contains the prototypes for the _spin_*() APIs.
	24	*
	25	* linux/spinlock.h: builds the final spin_*() APIs.
	26	*
	27	* on UP builds:
	28	*
	29	* linux/spinlock_type_up.h:
	30	* contains the generic, simplified UP spinlock type.
	31	* (which is an empty structure on non-debug builds)
	32	*
	33	* linux/spinlock_types.h:
	34	* defines the generic type and initializers
	35	*
	36	* linux/spinlock_up.h:
	37	* contains the __raw_spin_*()/etc. version of UP
	38	* builds. (which are NOPs on non-debug, non-preempt
	39	* builds)
	40	*
	41	* (included on UP-non-debug builds:)
	42	*
	43	* linux/spinlock_api_up.h:
	44	* builds the _spin_*() APIs.
	45	*
	46	* linux/spinlock.h: builds the final spin_*() APIs.
1da177e4 LT	47	*/
1da177e4 LT	48
1da177e4 LT	49	#include <linux/preempt.h>
	50	#include <linux/linkage.h>
	51	#include <linux/compiler.h>
	52	#include <linux/thread_info.h>
	53	#include <linux/kernel.h>
	54	#include <linux/stringify.h>
	55
1da177e4 LT	56	#include <asm/system.h>
	57
	58	/*
	59	* Must define these before including other files, inline functions need them
	60	*/
f83b5e32	61	#define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME
1da177e4 LT	62
	63	#define LOCK_SECTION_START(extra) \
	64	".subsection 1\n\t" \
	65	extra \
	66	".ifndef " LOCK_SECTION_NAME "\n\t" \
	67	LOCK_SECTION_NAME ":\n\t" \
	68	".endif\n"
	69
	70	#define LOCK_SECTION_END \
	71	".previous\n\t"
	72
	73	#define __lockfunc fastcall __attribute__((section(".spinlock.text")))
	74
	75	/*
fb1c8f93	76	* Pull the raw_spinlock_t and raw_rwlock_t definitions:
1da177e4	77	*/
fb1c8f93	78	#include <linux/spinlock_types.h>
1da177e4	79
fb1c8f93	80	extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
1da177e4	81
1da177e4	82	/*
fb1c8f93	83	* Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
1da177e4	84	*/
8a25d5de	85	#ifdef CONFIG_SMP
fb1c8f93	86	# include <asm/spinlock.h>
1da177e4	87	#else
fb1c8f93	88	# include <linux/spinlock_up.h>
1da177e4 LT	89	#endif
1da177e4 LT	90
8a25d5de IM	91	#ifdef CONFIG_DEBUG_SPINLOCK
	92	extern void __spin_lock_init(spinlock_t lock, const char name,
	93	struct lock_class_key *key);
	94	# define spin_lock_init(lock) \
	95	do { \
	96	static struct lock_class_key __key; \
	97	\
	98	__spin_lock_init((lock), #lock, &__key); \
	99	} while (0)
	100
	101	#else
	102	# define spin_lock_init(lock) \
	103	do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
	104	#endif
	105
	106	#ifdef CONFIG_DEBUG_SPINLOCK
	107	extern void __rwlock_init(rwlock_t lock, const char name,
	108	struct lock_class_key *key);
	109	# define rwlock_init(lock) \
	110	do { \
	111	static struct lock_class_key __key; \
	112	\
	113	__rwlock_init((lock), #lock, &__key); \
	114	} while (0)
	115	#else
	116	# define rwlock_init(lock) \
	117	do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
	118	#endif
fb1c8f93 IM	119
	120	#define spin_is_locked(lock) __raw_spin_is_locked(&(lock)->raw_lock)
	121
	122	/**
	123	* spin_unlock_wait - wait until the spinlock gets unlocked
	124	* @lock: the spinlock in question.
	125	*/
	126	#define spin_unlock_wait(lock) __raw_spin_unlock_wait(&(lock)->raw_lock)
	127
1da177e4	128	/*
fb1c8f93	129	* Pull the _spin_()/_read_()/_write_*() functions/declarations:
1da177e4	130	*/
fb1c8f93 IM	131	#if defined(CONFIG_SMP) \|\| defined(CONFIG_DEBUG_SPINLOCK)
fb1c8f93 IM	132	# include <linux/spinlock_api_smp.h>
1da177e4	133	#else
fb1c8f93	134	# include <linux/spinlock_api_up.h>
1da177e4 LT	135	#endif
1da177e4 LT	136
fb1c8f93 IM	137	#ifdef CONFIG_DEBUG_SPINLOCK
	138	extern void _raw_spin_lock(spinlock_t *lock);
	139	#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
	140	extern int _raw_spin_trylock(spinlock_t *lock);
	141	extern void _raw_spin_unlock(spinlock_t *lock);
fb1c8f93 IM	142	extern void _raw_read_lock(rwlock_t *lock);
	143	extern int _raw_read_trylock(rwlock_t *lock);
	144	extern void _raw_read_unlock(rwlock_t *lock);
	145	extern void _raw_write_lock(rwlock_t *lock);
	146	extern int _raw_write_trylock(rwlock_t *lock);
	147	extern void _raw_write_unlock(rwlock_t *lock);
	148	#else
fb1c8f93 IM	149	# define _raw_spin_lock(lock) __raw_spin_lock(&(lock)->raw_lock)
	150	# define _raw_spin_lock_flags(lock, flags) \
	151	__raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
8a25d5de IM	152	# define _raw_spin_trylock(lock) __raw_spin_trylock(&(lock)->raw_lock)
8a25d5de IM	153	# define _raw_spin_unlock(lock) __raw_spin_unlock(&(lock)->raw_lock)
fb1c8f93	154	# define _raw_read_lock(rwlock) __raw_read_lock(&(rwlock)->raw_lock)
fb1c8f93	155	# define _raw_read_trylock(rwlock) __raw_read_trylock(&(rwlock)->raw_lock)
8a25d5de IM	156	# define _raw_read_unlock(rwlock) __raw_read_unlock(&(rwlock)->raw_lock)
8a25d5de IM	157	# define _raw_write_lock(rwlock) __raw_write_lock(&(rwlock)->raw_lock)
fb1c8f93	158	# define _raw_write_trylock(rwlock) __raw_write_trylock(&(rwlock)->raw_lock)
8a25d5de	159	# define _raw_write_unlock(rwlock) __raw_write_unlock(&(rwlock)->raw_lock)
fb1c8f93	160	#endif
1da177e4	161
fb1c8f93 IM	162	#define read_can_lock(rwlock) __raw_read_can_lock(&(rwlock)->raw_lock)
fb1c8f93 IM	163	#define write_can_lock(rwlock) __raw_write_can_lock(&(rwlock)->raw_lock)
1da177e4 LT	164
	165	/*
	166	* Define the various spin_lock and rw_lock methods. Note we define these
	167	* regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
	168	* methods are defined as nops in the case they are not required.
	169	*/
fb1c8f93 IM	170	#define spin_trylock(lock) __cond_lock(_spin_trylock(lock))
	171	#define read_trylock(lock) __cond_lock(_read_trylock(lock))
	172	#define write_trylock(lock) __cond_lock(_write_trylock(lock))
1da177e4	173
fb1c8f93	174	#define spin_lock(lock) _spin_lock(lock)
8a25d5de IM	175
	176	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	177	# define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
	178	#else
	179	# define spin_lock_nested(lock, subclass) _spin_lock(lock)
	180	#endif
	181
fb1c8f93 IM	182	#define write_lock(lock) _write_lock(lock)
fb1c8f93 IM	183	#define read_lock(lock) _read_lock(lock)
1da177e4	184
fb1c8f93	185	#if defined(CONFIG_SMP) \|\| defined(CONFIG_DEBUG_SPINLOCK)
1da177e4 LT	186	#define spin_lock_irqsave(lock, flags) flags = _spin_lock_irqsave(lock)
	187	#define read_lock_irqsave(lock, flags) flags = _read_lock_irqsave(lock)
	188	#define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
	189	#else
	190	#define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
	191	#define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
	192	#define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
	193	#endif
	194
	195	#define spin_lock_irq(lock) _spin_lock_irq(lock)
	196	#define spin_lock_bh(lock) _spin_lock_bh(lock)
	197
	198	#define read_lock_irq(lock) _read_lock_irq(lock)
	199	#define read_lock_bh(lock) _read_lock_bh(lock)
	200
	201	#define write_lock_irq(lock) _write_lock_irq(lock)
	202	#define write_lock_bh(lock) _write_lock_bh(lock)
	203
bda98685 IM	204	/*
	205	* We inline the unlock functions in the nondebug case:
	206	*/
8a25d5de IM	207	#if defined(CONFIG_DEBUG_SPINLOCK) \|\| defined(CONFIG_PREEMPT) \|\| \
8a25d5de IM	208	!defined(CONFIG_SMP)
bda98685 IM	209	# define spin_unlock(lock) _spin_unlock(lock)
	210	# define read_unlock(lock) _read_unlock(lock)
	211	# define write_unlock(lock) _write_unlock(lock)
bda98685 IM	212	# define spin_unlock_irq(lock) _spin_unlock_irq(lock)
	213	# define read_unlock_irq(lock) _read_unlock_irq(lock)
	214	# define write_unlock_irq(lock) _write_unlock_irq(lock)
	215	#else
8a25d5de IM	216	# define spin_unlock(lock) __raw_spin_unlock(&(lock)->raw_lock)
	217	# define read_unlock(lock) __raw_read_unlock(&(lock)->raw_lock)
	218	# define write_unlock(lock) __raw_write_unlock(&(lock)->raw_lock)
bda98685 IM	219	# define spin_unlock_irq(lock) \
	220	do { __raw_spin_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
	221	# define read_unlock_irq(lock) \
	222	do { __raw_read_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
	223	# define write_unlock_irq(lock) \
	224	do { __raw_write_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
	225	#endif
1da177e4	226
fb1c8f93 IM	227	#define spin_unlock_irqrestore(lock, flags) \
fb1c8f93 IM	228	_spin_unlock_irqrestore(lock, flags)
1da177e4 LT	229	#define spin_unlock_bh(lock) _spin_unlock_bh(lock)
1da177e4 LT	230
fb1c8f93 IM	231	#define read_unlock_irqrestore(lock, flags) \
fb1c8f93 IM	232	_read_unlock_irqrestore(lock, flags)
fb1c8f93	233	#define read_unlock_bh(lock) _read_unlock_bh(lock)
1da177e4	234
fb1c8f93 IM	235	#define write_unlock_irqrestore(lock, flags) \
fb1c8f93 IM	236	_write_unlock_irqrestore(lock, flags)
fb1c8f93	237	#define write_unlock_bh(lock) _write_unlock_bh(lock)
1da177e4	238
fb1c8f93	239	#define spin_trylock_bh(lock) __cond_lock(_spin_trylock_bh(lock))
1da177e4 LT	240
	241	#define spin_trylock_irq(lock) \
	242	({ \
	243	local_irq_disable(); \
	244	_spin_trylock(lock) ? \
fb1c8f93	245	1 : ({ local_irq_enable(); 0; }); \
1da177e4 LT	246	})
	247
	248	#define spin_trylock_irqsave(lock, flags) \
	249	({ \
	250	local_irq_save(flags); \
	251	_spin_trylock(lock) ? \
fb1c8f93	252	1 : ({ local_irq_restore(flags); 0; }); \
1da177e4 LT	253	})
1da177e4 LT	254
1da177e4	255	/*
fb1c8f93 IM	256	* Pull the atomic_t declaration:
fb1c8f93 IM	257	* (asm-mips/atomic.h needs above definitions)
1da177e4	258	*/
fb1c8f93 IM	259	#include <asm/atomic.h>
	260	/**
	261	* atomic_dec_and_lock - lock on reaching reference count zero
	262	* @atomic: the atomic counter
	263	* @lock: the spinlock in question
1da177e4	264	*/
fb1c8f93 IM	265	extern int _atomic_dec_and_lock(atomic_t atomic, spinlock_t lock);
	266	#define atomic_dec_and_lock(atomic, lock) \
	267	__cond_lock(_atomic_dec_and_lock(atomic, lock))
1da177e4 LT	268
	269	/**
	270	* spin_can_lock - would spin_trylock() succeed?
	271	* @lock: the spinlock in question.
	272	*/
fb1c8f93	273	#define spin_can_lock(lock) (!spin_is_locked(lock))
1da177e4 LT	274
1da177e4 LT	275	#endif /* __LINUX_SPINLOCK_H */