[mirror_spl-debian.git] / include / sys / rwlock.h

/*****************************************************************************\
 *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
 *  Copyright (C) 2007 The Regents of the University of California.
 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
 *  UCRL-CODE-235197
 *
 *  This file is part of the SPL, Solaris Porting Layer.
 *  For details, see <http://github.com/behlendorf/spl/>.
 *
 *  The SPL is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by the
 *  Free Software Foundation; either version 2 of the License, or (at your
 *  option) any later version.
 *
 *  The SPL is distributed in the hope that it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
\*****************************************************************************/

#ifndef _SPL_RWLOCK_H
#define _SPL_RWLOCK_H

#include <sys/types.h>
#include <linux/rwsem.h>

typedef enum {
        RW_DRIVER  = 2,
        RW_DEFAULT = 4
} krw_type_t;

typedef enum {
        RW_NONE   = 0,
        RW_WRITER = 1,
        RW_READER = 2
} krw_t;

typedef struct {
        struct rw_semaphore rw_rwlock;
        kthread_t *rw_owner;
} krwlock_t;

/*
 * For the generic implementations of rw-semaphores the following is
 * true.  If your semaphore implementation internally represents the
 * semaphore state differently.  Then special case handling will be
 * required so RW_COUNT() provides these semantics:
 * - if activity/count is 0 then there are no active readers or writers
 * - if activity/count is +ve then that is the number of active readers
 * - if activity/count is -1 then there is one active writer
 */
#define SEM(rwp)                        ((struct rw_semaphore *)(rwp))

#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
# define RW_COUNT(rwp)                  (SEM(rwp)->activity)
# define rw_exit_locked(rwp)            __up_read_locked(rwp)
# define rw_tryenter_locked(rwp)        __down_write_trylock_locked(rwp)
extern void __up_read_locked(struct rw_semaphore *);
extern int __down_write_trylock_locked(struct rw_semaphore *);
#else
/*
 * 2.6.x  - 2.6.27  use guard macro _I386_RWSEM_H
 * 2.6.28 - 2.6.32+ use guard macro _ASM_X86_RWSEM_H
 */
# if defined(_I386_RWSEM_H) || defined(_ASM_X86_RWSEM_H)
#  define RW_COUNT(rwp)                 ((SEM(rwp)->count < 0) ? (-1) : \
                                        (SEM(rwp)->count & RWSEM_ACTIVE_MASK))
# else
#  define RW_COUNT(rwp)                 (SEM(rwp)->count & RWSEM_ACTIVE_MASK)
# endif
# define rw_exit_locked(rwp)           up_read(rwp)
# define rw_tryenter_locked(rwp)       down_write_trylock(rwp)
#endif

static inline kthread_t *
spl_rw_get_owner(krwlock_t *rwp)
{
        return rwp->rw_owner;
}

static inline void
spl_rw_set_owner(krwlock_t *rwp)
{
        unsigned long flags;

        spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
        rwp->rw_owner = current;
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
}

static inline void
spl_rw_clear_owner(krwlock_t *rwp)
{
        unsigned long flags;

        spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
        rwp->rw_owner = NULL;
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
}

static inline kthread_t *
rw_owner(krwlock_t *rwp)
{
        unsigned long flags;
        kthread_t *owner;

        spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
        owner = spl_rw_get_owner(rwp);
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);

        return owner;
}

static inline int
RW_READ_HELD(krwlock_t *rwp)
{
        unsigned long flags;
        int rc;

        spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
        rc = ((RW_COUNT(rwp) > 0) && (spl_rw_get_owner(rwp) == NULL));
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);

        return rc;
}

static inline int
RW_WRITE_HELD(krwlock_t *rwp)
{
        unsigned long flags;
        int rc;

        spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
        rc = ((RW_COUNT(rwp) < 0) && (spl_rw_get_owner(rwp) == current));
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);

        return rc;
}

static inline int
RW_LOCK_HELD(krwlock_t *rwp)
{
        unsigned long flags;
        int rc;

        spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
        rc = (RW_COUNT(rwp) != 0);
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);

        return rc;
}

/*
 * The following functions must be a #define and not static inline.
 * This ensures that the native linux semaphore functions (down/up)
 * will be correctly located in the users code which is important
 * for the built in kernel lock analysis tools
 */
#define rw_init(rwp, name, type, arg)                                   \
({                                                                      \
        static struct lock_class_key __key;                             \
                                                                        \
        __init_rwsem(SEM(rwp), #rwp, &__key);                           \
        spl_rw_clear_owner(rwp);                                        \
})

#define rw_destroy(rwp)                                                 \
({                                                                      \
        VERIFY(!RW_LOCK_HELD(rwp));                                     \
})

#define rw_tryenter(rwp, rw)                                            \
({                                                                      \
        int _rc_ = 0;                                                   \
                                                                        \
        switch (rw) {                                                   \
        case RW_READER:                                                 \
                _rc_ = down_read_trylock(SEM(rwp));                     \
                break;                                                  \
        case RW_WRITER:                                                 \
                if ((_rc_ = down_write_trylock(SEM(rwp))))              \
                        spl_rw_set_owner(rwp);                          \
                break;                                                  \
        default:                                                        \
                SBUG();                                                 \
        }                                                               \
        _rc_;                                                           \
})

#define rw_enter(rwp, rw)                                               \
({                                                                      \
        switch (rw) {                                                   \
        case RW_READER:                                                 \
                down_read(SEM(rwp));                                    \
                break;                                                  \
        case RW_WRITER:                                                 \
                down_write(SEM(rwp));                                   \
                spl_rw_set_owner(rwp);                                  \
                break;                                                  \
        default:                                                        \
                SBUG();                                                 \
        }                                                               \
})

#define rw_exit(rwp)                                                    \
({                                                                      \
        if (RW_WRITE_HELD(rwp)) {                                       \
                spl_rw_clear_owner(rwp);                                \
                up_write(SEM(rwp));                                     \
        } else {                                                        \
                ASSERT(RW_READ_HELD(rwp));                              \
                up_read(SEM(rwp));                                      \
        }                                                               \
})

#define rw_downgrade(rwp)                                               \
({                                                                      \
        spl_rw_clear_owner(rwp);                                        \
        downgrade_write(SEM(rwp));                                      \
})

#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
#define rw_tryupgrade(rwp)                                              \
({                                                                      \
        unsigned long _flags_;                                          \
        int _rc_ = 0;                                                   \
                                                                        \
        spin_lock_irqsave(&SEM(rwp)->wait_lock, _flags_);               \
        if (list_empty(&SEM(rwp)->wait_list) && (RW_COUNT(rwp) == 1)) { \
                rw_exit_locked(SEM(rwp));                               \
                VERIFY(_rc_ = rw_tryenter_locked(SEM(rwp)));            \
                (rwp)->rw_owner = current;                              \
        }                                                               \
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, _flags_);          \
        _rc_;                                                           \
})
#else
/*
 * This can be done correctly but for each supported arch we will need
 * a custom cmpxchg() to atomically check and promote the rwsem.  That's
 * not worth the trouble for now so rw_tryupgrade() will always fail.
 */
#define rw_tryupgrade(rwp)      ({ 0; })
#endif

int spl_rw_init(void);
void spl_rw_fini(void);

#endif /* _SPL_RWLOCK_H */
Commit	Line	Data
716154c5 BB	1	/*****************************************************************************\
	2	* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
	3	* Copyright (C) 2007 The Regents of the University of California.
	4	* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
	5	* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
715f6251	6	* UCRL-CODE-235197
715f6251	7	*
716154c5 BB	8	* This file is part of the SPL, Solaris Porting Layer.
	9	* For details, see <http://github.com/behlendorf/spl/>.
	10	*
	11	* The SPL is free software; you can redistribute it and/or modify it
	12	* under the terms of the GNU General Public License as published by the
	13	* Free Software Foundation; either version 2 of the License, or (at your
	14	* option) any later version.
715f6251	15	*
716154c5	16	* The SPL is distributed in the hope that it will be useful, but WITHOUT
715f6251	17	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	18	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	19	* for more details.
	20	*
	21	* You should have received a copy of the GNU General Public License along
716154c5 BB	22	* with the SPL. If not, see <http://www.gnu.org/licenses/>.
716154c5 BB	23	\*****************************************************************************/
715f6251	24
09b414e8	25	#ifndef _SPL_RWLOCK_H
e8b31e84	26	#define _SPL_RWLOCK_H
f1ca4da6	27
f4b37741	28	#include <sys/types.h>
d28db80f	29	#include <linux/rwsem.h>
f1ca4da6	30
f1ca4da6	31	typedef enum {
e811949a BB	32	RW_DRIVER = 2,
e811949a BB	33	RW_DEFAULT = 4
f1ca4da6	34	} krw_type_t;
	35
	36	typedef enum {
d28db80f	37	RW_NONE = 0,
e811949a BB	38	RW_WRITER = 1,
e811949a BB	39	RW_READER = 2
f1ca4da6	40	} krw_t;
f1ca4da6	41
d28db80f BB	42	typedef struct {
	43	struct rw_semaphore rw_rwlock;
	44	kthread_t *rw_owner;
	45	} krwlock_t;
f1ca4da6	46
e811949a	47	/*
5652e7b4 BB	48	* For the generic implementations of rw-semaphores the following is
	49	* true. If your semaphore implementation internally represents the
	50	* semaphore state differently. Then special case handling will be
	51	* required so RW_COUNT() provides these semantics:
e811949a BB	52	* - if activity/count is 0 then there are no active readers or writers
	53	* - if activity/count is +ve then that is the number of active readers
	54	* - if activity/count is -1 then there is one active writer
	55	*/
d28db80f BB	56	#define SEM(rwp) ((struct rw_semaphore *)(rwp))
d28db80f BB	57
e811949a	58	#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
d28db80f BB	59	# define RW_COUNT(rwp) (SEM(rwp)->activity)
	60	# define rw_exit_locked(rwp) __up_read_locked(rwp)
	61	# define rw_tryenter_locked(rwp) __down_write_trylock_locked(rwp)
	62	extern void __up_read_locked(struct rw_semaphore *);
	63	extern int __down_write_trylock_locked(struct rw_semaphore *);
e811949a	64	#else
3a03ce5c BB	65	/*
	66	* 2.6.x - 2.6.27 use guard macro _I386_RWSEM_H
	67	* 2.6.28 - 2.6.32+ use guard macro _ASM_X86_RWSEM_H
	68	*/
	69	# if defined(_I386_RWSEM_H) \|\| defined(_ASM_X86_RWSEM_H)
5652e7b4	70	# define RW_COUNT(rwp) ((SEM(rwp)->count < 0) ? (-1) : \
ef6c1368	71	(SEM(rwp)->count & RWSEM_ACTIVE_MASK))
5652e7b4 BB	72	# else
	73	# define RW_COUNT(rwp) (SEM(rwp)->count & RWSEM_ACTIVE_MASK)
	74	# endif
	75	# define rw_exit_locked(rwp) up_read(rwp)
	76	# define rw_tryenter_locked(rwp) down_write_trylock(rwp)
e811949a	77	#endif
f1ca4da6	78
d28db80f BB	79	static inline kthread_t *
	80	spl_rw_get_owner(krwlock_t *rwp)
	81	{
	82	return rwp->rw_owner;
	83	}
	84
	85	static inline void
	86	spl_rw_set_owner(krwlock_t *rwp)
	87	{
	88	unsigned long flags;
	89
	90	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	91	rwp->rw_owner = current;
	92	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	93	}
	94
	95	static inline void
	96	spl_rw_clear_owner(krwlock_t *rwp)
	97	{
	98	unsigned long flags;
	99
	100	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	101	rwp->rw_owner = NULL;
	102	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	103	}
	104
	105	static inline kthread_t *
	106	rw_owner(krwlock_t *rwp)
	107	{
	108	unsigned long flags;
	109	kthread_t *owner;
	110
	111	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	112	owner = spl_rw_get_owner(rwp);
	113	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	114
	115	return owner;
	116	}
	117
	118	static inline int
	119	RW_READ_HELD(krwlock_t *rwp)
	120	{
	121	unsigned long flags;
	122	int rc;
	123
	124	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	125	rc = ((RW_COUNT(rwp) > 0) && (spl_rw_get_owner(rwp) == NULL));
	126	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	127
	128	return rc;
	129	}
	130
	131	static inline int
	132	RW_WRITE_HELD(krwlock_t *rwp)
	133	{
	134	unsigned long flags;
	135	int rc;
	136
	137	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	138	rc = ((RW_COUNT(rwp) < 0) && (spl_rw_get_owner(rwp) == current));
	139	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	140
	141	return rc;
	142	}
143
144	static inline int
145	RW_LOCK_HELD(krwlock_t *rwp)
146	{
147	unsigned long flags;
148	int rc;
149
150	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
151	rc = (RW_COUNT(rwp) != 0);
152	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
153
154	return rc;
155	}
156
157	/*
158	* The following functions must be a #define and not static inline.
159	* This ensures that the native linux semaphore functions (down/up)
160	* will be correctly located in the users code which is important
161	* for the built in kernel lock analysis tools
162	*/
163	#define rw_init(rwp, name, type, arg) \
164	({ \
0e77fc11 BB	165	static struct lock_class_key __key; \
	166	\
	167	__init_rwsem(SEM(rwp), #rwp, &__key); \
d28db80f	168	spl_rw_clear_owner(rwp); \
e811949a	169	})
f1ca4da6	170
d28db80f BB	171	#define rw_destroy(rwp) \
	172	({ \
	173	VERIFY(!RW_LOCK_HELD(rwp)); \
e811949a	174	})
ed61a7d0	175
d28db80f BB	176	#define rw_tryenter(rwp, rw) \
	177	({ \
	178	int _rc_ = 0; \
	179	\
	180	switch (rw) { \
	181	case RW_READER: \
	182	_rc_ = down_read_trylock(SEM(rwp)); \
	183	break; \
	184	case RW_WRITER: \
	185	if ((_rc_ = down_write_trylock(SEM(rwp)))) \
	186	spl_rw_set_owner(rwp); \
	187	break; \
	188	default: \
	189	SBUG(); \
	190	} \
	191	_rc_; \
e8b31e84	192	})
e8b31e84	193
d28db80f BB	194	#define rw_enter(rwp, rw) \
	195	({ \
	196	switch (rw) { \
	197	case RW_READER: \
	198	down_read(SEM(rwp)); \
	199	break; \
	200	case RW_WRITER: \
	201	down_write(SEM(rwp)); \
	202	spl_rw_set_owner(rwp); \
	203	break; \
	204	default: \
	205	SBUG(); \
	206	} \
e811949a	207	})
f1ca4da6	208
d28db80f BB	209	#define rw_exit(rwp) \
	210	({ \
	211	if (RW_WRITE_HELD(rwp)) { \
	212	spl_rw_clear_owner(rwp); \
	213	up_write(SEM(rwp)); \
	214	} else { \
	215	ASSERT(RW_READ_HELD(rwp)); \
	216	up_read(SEM(rwp)); \
	217	} \
	218	})
	219
	220	#define rw_downgrade(rwp) \
	221	({ \
	222	spl_rw_clear_owner(rwp); \
	223	downgrade_write(SEM(rwp)); \
	224	})
	225
ef6c1368	226	#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
d28db80f BB	227	#define rw_tryupgrade(rwp) \
	228	({ \
	229	unsigned long _flags_; \
	230	int _rc_ = 0; \
	231	\
	232	spin_lock_irqsave(&SEM(rwp)->wait_lock, _flags_); \
	233	if (list_empty(&SEM(rwp)->wait_list) && (RW_COUNT(rwp) == 1)) { \
	234	rw_exit_locked(SEM(rwp)); \
	235	VERIFY(_rc_ = rw_tryenter_locked(SEM(rwp))); \
	236	(rwp)->rw_owner = current; \
	237	} \
	238	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, _flags_); \
	239	_rc_; \
	240	})
ef6c1368 BB	241	#else
	242	/*
	243	* This can be done correctly but for each supported arch we will need
	244	* a custom cmpxchg() to atomically check and promote the rwsem. That's
	245	* not worth the trouble for now so rw_tryupgrade() will always fail.
	246	*/
	247	#define rw_tryupgrade(rwp) ({ 0; })
	248	#endif
d28db80f BB	249
	250	int spl_rw_init(void);
	251	void spl_rw_fini(void);
	252
e8b31e84	253	#endif /* _SPL_RWLOCK_H */