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

/*
 *  This file is part of the SPL: Solaris Porting Layer.
 *
 *  Copyright (c) 2009 Lawrence Livermore National Security, LLC.
 *  Produced at Lawrence Livermore National Laboratory
 *  Written by:
 *          Brian Behlendorf <behlendorf1@llnl.gov>,
 *          Herb Wartens <wartens2@llnl.gov>,
 *          Jim Garlick <garlick@llnl.gov>
 *  UCRL-CODE-235197
 *
 *  This 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.
 *
 *  This 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 this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
 */

#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
# ifdef _I386_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));                                      \
})

#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_;                                                           \
})

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

#endif /* _SPL_RWLOCK_H */
Commit	Line	Data
715f6251	1	/*
	2	* This file is part of the SPL: Solaris Porting Layer.
	3	*
e811949a	4	* Copyright (c) 2009 Lawrence Livermore National Security, LLC.
715f6251	5	* Produced at Lawrence Livermore National Laboratory
	6	* Written by:
	7	* Brian Behlendorf <behlendorf1@llnl.gov>,
	8	* Herb Wartens <wartens2@llnl.gov>,
	9	* Jim Garlick <garlick@llnl.gov>
	10	* UCRL-CODE-235197
	11	*
	12	* This is free software; you can redistribute it and/or modify it
	13	* under the terms of the GNU General Public License as published by
	14	* the Free Software Foundation; either version 2 of the License, or
	15	* (at your option) any later version.
	16	*
	17	* This is distributed in the hope that it will be useful, but WITHOUT
	18	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	19	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	20	* for more details.
	21	*
	22	* You should have received a copy of the GNU General Public License along
	23	* with this program; if not, write to the Free Software Foundation, Inc.,
	24	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	25	*/
	26
09b414e8	27	#ifndef _SPL_RWLOCK_H
e8b31e84	28	#define _SPL_RWLOCK_H
f1ca4da6	29
f4b37741	30	#include <sys/types.h>
d28db80f	31	#include <linux/rwsem.h>
f1ca4da6	32
f1ca4da6	33	typedef enum {
e811949a BB	34	RW_DRIVER = 2,
e811949a BB	35	RW_DEFAULT = 4
f1ca4da6	36	} krw_type_t;
	37
	38	typedef enum {
d28db80f	39	RW_NONE = 0,
e811949a BB	40	RW_WRITER = 1,
e811949a BB	41	RW_READER = 2
f1ca4da6	42	} krw_t;
f1ca4da6	43
d28db80f BB	44	typedef struct {
	45	struct rw_semaphore rw_rwlock;
	46	kthread_t *rw_owner;
	47	} krwlock_t;
f1ca4da6	48
e811949a	49	/*
5652e7b4 BB	50	* For the generic implementations of rw-semaphores the following is
	51	* true. If your semaphore implementation internally represents the
	52	* semaphore state differently. Then special case handling will be
	53	* required so RW_COUNT() provides these semantics:
e811949a BB	54	* - if activity/count is 0 then there are no active readers or writers
	55	* - if activity/count is +ve then that is the number of active readers
	56	* - if activity/count is -1 then there is one active writer
	57	*/
d28db80f BB	58	#define SEM(rwp) ((struct rw_semaphore *)(rwp))
d28db80f BB	59
e811949a	60	#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
d28db80f BB	61	# define RW_COUNT(rwp) (SEM(rwp)->activity)
	62	# define rw_exit_locked(rwp) __up_read_locked(rwp)
	63	# define rw_tryenter_locked(rwp) __down_write_trylock_locked(rwp)
	64	extern void __up_read_locked(struct rw_semaphore *);
	65	extern int __down_write_trylock_locked(struct rw_semaphore *);
e811949a	66	#else
5652e7b4 BB	67	# ifdef _I386_RWSEM_H
	68	# define RW_COUNT(rwp) ((SEM(rwp)->count < 0) ? (-1) : \
	69	(SEM(rwp)->count & RWSEM_ACTIVE_MASK))
	70	# else
	71	# define RW_COUNT(rwp) (SEM(rwp)->count & RWSEM_ACTIVE_MASK)
	72	# endif
	73	# define rw_exit_locked(rwp) up_read(rwp)
	74	# define rw_tryenter_locked(rwp) down_write_trylock(rwp)
e811949a	75	#endif
f1ca4da6	76
d28db80f BB	77	static inline kthread_t *
	78	spl_rw_get_owner(krwlock_t *rwp)
	79	{
	80	return rwp->rw_owner;
	81	}
	82
	83	static inline void
	84	spl_rw_set_owner(krwlock_t *rwp)
	85	{
	86	unsigned long flags;
	87
	88	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	89	rwp->rw_owner = current;
	90	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	91	}
	92
	93	static inline void
	94	spl_rw_clear_owner(krwlock_t *rwp)
	95	{
	96	unsigned long flags;
	97
	98	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	99	rwp->rw_owner = NULL;
	100	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	101	}
	102
	103	static inline kthread_t *
	104	rw_owner(krwlock_t *rwp)
	105	{
	106	unsigned long flags;
	107	kthread_t *owner;
	108
	109	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	110	owner = spl_rw_get_owner(rwp);
	111	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	112
	113	return owner;
	114	}
	115
	116	static inline int
	117	RW_READ_HELD(krwlock_t *rwp)
	118	{
	119	unsigned long flags;
	120	int rc;
	121
	122	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	123	rc = ((RW_COUNT(rwp) > 0) && (spl_rw_get_owner(rwp) == NULL));
	124	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	125
	126	return rc;
	127	}
	128
	129	static inline int
	130	RW_WRITE_HELD(krwlock_t *rwp)
	131	{
	132	unsigned long flags;
	133	int rc;
	134
	135	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	136	rc = ((RW_COUNT(rwp) < 0) && (spl_rw_get_owner(rwp) == current));
	137	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	138
	139	return rc;
	140	}
141
142	static inline int
143	RW_LOCK_HELD(krwlock_t *rwp)
144	{
145	unsigned long flags;
146	int rc;
147
148	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
149	rc = (RW_COUNT(rwp) != 0);
150	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
151
152	return rc;
153	}
154
155	/*
156	* The following functions must be a #define and not static inline.
157	* This ensures that the native linux semaphore functions (down/up)
158	* will be correctly located in the users code which is important
159	* for the built in kernel lock analysis tools
160	*/
161	#define rw_init(rwp, name, type, arg) \
162	({ \
0e77fc11 BB	163	static struct lock_class_key __key; \
	164	\
	165	__init_rwsem(SEM(rwp), #rwp, &__key); \
d28db80f	166	spl_rw_clear_owner(rwp); \
e811949a	167	})
f1ca4da6	168
d28db80f BB	169	#define rw_destroy(rwp) \
	170	({ \
	171	VERIFY(!RW_LOCK_HELD(rwp)); \
e811949a	172	})
ed61a7d0	173
d28db80f BB	174	#define rw_tryenter(rwp, rw) \
	175	({ \
	176	int _rc_ = 0; \
	177	\
	178	switch (rw) { \
	179	case RW_READER: \
	180	_rc_ = down_read_trylock(SEM(rwp)); \
	181	break; \
	182	case RW_WRITER: \
	183	if ((_rc_ = down_write_trylock(SEM(rwp)))) \
	184	spl_rw_set_owner(rwp); \
	185	break; \
	186	default: \
	187	SBUG(); \
	188	} \
	189	_rc_; \
e8b31e84	190	})
e8b31e84	191
d28db80f BB	192	#define rw_enter(rwp, rw) \
	193	({ \
	194	switch (rw) { \
	195	case RW_READER: \
	196	down_read(SEM(rwp)); \
	197	break; \
	198	case RW_WRITER: \
	199	down_write(SEM(rwp)); \
	200	spl_rw_set_owner(rwp); \
	201	break; \
	202	default: \
	203	SBUG(); \
	204	} \
e811949a	205	})
f1ca4da6	206
d28db80f BB	207	#define rw_exit(rwp) \
	208	({ \
	209	if (RW_WRITE_HELD(rwp)) { \
	210	spl_rw_clear_owner(rwp); \
	211	up_write(SEM(rwp)); \
	212	} else { \
	213	ASSERT(RW_READ_HELD(rwp)); \
	214	up_read(SEM(rwp)); \
	215	} \
	216	})
	217
	218	#define rw_downgrade(rwp) \
	219	({ \
	220	spl_rw_clear_owner(rwp); \
	221	downgrade_write(SEM(rwp)); \
	222	})
	223
	224	#define rw_tryupgrade(rwp) \
	225	({ \
	226	unsigned long _flags_; \
	227	int _rc_ = 0; \
	228	\
	229	spin_lock_irqsave(&SEM(rwp)->wait_lock, _flags_); \
	230	if (list_empty(&SEM(rwp)->wait_list) && (RW_COUNT(rwp) == 1)) { \
	231	rw_exit_locked(SEM(rwp)); \
	232	VERIFY(_rc_ = rw_tryenter_locked(SEM(rwp))); \
	233	(rwp)->rw_owner = current; \
	234	} \
	235	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, _flags_); \
	236	_rc_; \
	237	})
	238
	239	int spl_rw_init(void);
	240	void spl_rw_fini(void);
	241
e8b31e84	242	#endif /* _SPL_RWLOCK_H */