[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;

#define SEM(rwp)                        ((struct rw_semaphore *)(rwp))

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 = (rwsem_is_locked(SEM(rwp)) && 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 = (rwsem_is_locked(SEM(rwp)) && 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 = rwsem_is_locked(SEM(rwp));
        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)
/*
 * 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 is required.
 * - 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
 */

extern void __up_read_locked(struct rw_semaphore *);
extern int __down_write_trylock_locked(struct rw_semaphore *);

#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)) &&                       \
            (SEM(rwp)->activity == 1)) {                                \
                __up_read_locked(SEM(rwp));                             \
                VERIFY(_rc_ = __down_write_trylock_locked(SEM(rwp)));   \
                (rwp)->rw_owner = current;                              \
        }                                                               \
        spin_unlock_irqrestore(&SEM(rwp)->wait_lock, _flags_);          \
        _rc_;                                                           \
})
#else
/*
 * rw_tryupgrade() can be implemented correctly but for each supported
 * arch we will need a custom implementation.  For the x86 implementation
 * it looks like a custom cmpxchg() to atomically check and promote the
 * rwsem would be safe.  For now that's not worth the trouble so in this
 * case rw_tryupgrade() has just been disabled.
 */
#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
d28db80f BB	47	#define SEM(rwp) ((struct rw_semaphore *)(rwp))
d28db80f BB	48
d28db80f BB	49	static inline kthread_t *
	50	spl_rw_get_owner(krwlock_t *rwp)
	51	{
	52	return rwp->rw_owner;
	53	}
	54
	55	static inline void
	56	spl_rw_set_owner(krwlock_t *rwp)
	57	{
	58	unsigned long flags;
	59
	60	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	61	rwp->rw_owner = current;
	62	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	63	}
	64
	65	static inline void
	66	spl_rw_clear_owner(krwlock_t *rwp)
	67	{
	68	unsigned long flags;
	69
	70	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	71	rwp->rw_owner = NULL;
	72	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	73	}
	74
	75	static inline kthread_t *
	76	rw_owner(krwlock_t *rwp)
	77	{
	78	unsigned long flags;
	79	kthread_t *owner;
	80
	81	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
	82	owner = spl_rw_get_owner(rwp);
	83	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	84
	85	return owner;
	86	}
	87
	88	static inline int
	89	RW_READ_HELD(krwlock_t *rwp)
	90	{
	91	unsigned long flags;
	92	int rc;
	93
	94	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
32f5faff	95	rc = (rwsem_is_locked(SEM(rwp)) && spl_rw_get_owner(rwp) == NULL);
d28db80f BB	96	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	97
	98	return rc;
	99	}
	100
	101	static inline int
	102	RW_WRITE_HELD(krwlock_t *rwp)
	103	{
	104	unsigned long flags;
	105	int rc;
	106
	107	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
32f5faff	108	rc = (rwsem_is_locked(SEM(rwp)) && spl_rw_get_owner(rwp) == current);
d28db80f BB	109	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	110
	111	return rc;
	112	}
	113
	114	static inline int
	115	RW_LOCK_HELD(krwlock_t *rwp)
	116	{
	117	unsigned long flags;
	118	int rc;
	119
	120	spin_lock_irqsave(&SEM(rwp)->wait_lock, flags);
32f5faff	121	rc = rwsem_is_locked(SEM(rwp));
d28db80f BB	122	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, flags);
	123
	124	return rc;
	125	}
	126
	127	/*
	128	* The following functions must be a #define and not static inline.
	129	* This ensures that the native linux semaphore functions (down/up)
	130	* will be correctly located in the users code which is important
	131	* for the built in kernel lock analysis tools
	132	*/
	133	#define rw_init(rwp, name, type, arg) \
	134	({ \
0e77fc11 BB	135	static struct lock_class_key __key; \
	136	\
	137	__init_rwsem(SEM(rwp), #rwp, &__key); \
d28db80f	138	spl_rw_clear_owner(rwp); \
e811949a	139	})
f1ca4da6	140
d28db80f BB	141	#define rw_destroy(rwp) \
	142	({ \
	143	VERIFY(!RW_LOCK_HELD(rwp)); \
e811949a	144	})
ed61a7d0	145
d28db80f BB	146	#define rw_tryenter(rwp, rw) \
	147	({ \
	148	int _rc_ = 0; \
	149	\
	150	switch (rw) { \
	151	case RW_READER: \
	152	_rc_ = down_read_trylock(SEM(rwp)); \
	153	break; \
	154	case RW_WRITER: \
	155	if ((_rc_ = down_write_trylock(SEM(rwp)))) \
	156	spl_rw_set_owner(rwp); \
	157	break; \
	158	default: \
	159	SBUG(); \
	160	} \
	161	_rc_; \
e8b31e84	162	})
e8b31e84	163
d28db80f BB	164	#define rw_enter(rwp, rw) \
	165	({ \
	166	switch (rw) { \
	167	case RW_READER: \
	168	down_read(SEM(rwp)); \
	169	break; \
	170	case RW_WRITER: \
	171	down_write(SEM(rwp)); \
	172	spl_rw_set_owner(rwp); \
	173	break; \
	174	default: \
	175	SBUG(); \
	176	} \
e811949a	177	})
f1ca4da6	178
d28db80f BB	179	#define rw_exit(rwp) \
	180	({ \
	181	if (RW_WRITE_HELD(rwp)) { \
	182	spl_rw_clear_owner(rwp); \
	183	up_write(SEM(rwp)); \
	184	} else { \
	185	ASSERT(RW_READ_HELD(rwp)); \
	186	up_read(SEM(rwp)); \
	187	} \
	188	})
	189
	190	#define rw_downgrade(rwp) \
	191	({ \
	192	spl_rw_clear_owner(rwp); \
	193	downgrade_write(SEM(rwp)); \
	194	})
	195
ef6c1368	196	#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
32f5faff BB	197	/*
	198	* For the generic implementations of rw-semaphores the following is
	199	* true. If your semaphore implementation internally represents the
	200	* semaphore state differently then special case handling is required.
	201	* - if activity/count is 0 then there are no active readers or writers
	202	* - if activity/count is +ve then that is the number of active readers
	203	* - if activity/count is -1 then there is one active writer
	204	*/
	205
	206	extern void __up_read_locked(struct rw_semaphore *);
	207	extern int __down_write_trylock_locked(struct rw_semaphore *);
	208
d28db80f BB	209	#define rw_tryupgrade(rwp) \
	210	({ \
	211	unsigned long _flags_; \
	212	int _rc_ = 0; \
	213	\
	214	spin_lock_irqsave(&SEM(rwp)->wait_lock, _flags_); \
32f5faff BB	215	if ((list_empty(&SEM(rwp)->wait_list)) && \
	216	(SEM(rwp)->activity == 1)) { \
	217	__up_read_locked(SEM(rwp)); \
	218	VERIFY(_rc_ = __down_write_trylock_locked(SEM(rwp))); \
d28db80f BB	219	(rwp)->rw_owner = current; \
	220	} \
	221	spin_unlock_irqrestore(&SEM(rwp)->wait_lock, _flags_); \
	222	_rc_; \
	223	})
ef6c1368 BB	224	#else
ef6c1368 BB	225	/*
32f5faff BB	226	* rw_tryupgrade() can be implemented correctly but for each supported
	227	* arch we will need a custom implementation. For the x86 implementation
	228	* it looks like a custom cmpxchg() to atomically check and promote the
	229	* rwsem would be safe. For now that's not worth the trouble so in this
	230	* case rw_tryupgrade() has just been disabled.
ef6c1368 BB	231	*/
	232	#define rw_tryupgrade(rwp) ({ 0; })
	233	#endif
d28db80f BB	234
	235	int spl_rw_init(void);
	236	void spl_rw_fini(void);
	237
e8b31e84	238	#endif /* _SPL_RWLOCK_H */