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/*
* 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 <linux/module.h>
#include <linux/slab.h>
#include <linux/rwsem.h>
#include <sys/types.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 rw_semaphore krwlock_t;
#define rw_init(rwlp, name, type, arg) init_rwsem(rwlp)
#define rw_destroy(rwlp) ((void)0)
#define rw_downgrade(rwlp) downgrade_write(rwlp)
#define RW_LOCK_HELD(rwlp) rwsem_is_locked(rwlp)
/*
* the rw-semaphore definition
* - 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
*/
#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
# define RW_COUNT(rwlp) ((rwlp)->activity)
# define RW_READ_HELD(rwlp) ((RW_COUNT(rwlp) > 0) ? RW_COUNT(rwlp) : 0)
# define RW_WRITE_HELD(rwlp) ((RW_COUNT(rwlp) < 0))
# define rw_exit_locked(rwlp) __up_read_locked(rwlp)
# define rw_tryenter_locked(rwlp) __down_write_trylock_locked(rwlp)
void __up_read_locked(struct rw_semaphore *);
int __down_write_trylock_locked(struct rw_semaphore *);
#else
# define RW_COUNT(rwlp) ((rwlp)->count & RWSEM_ACTIVE_MASK)
# define RW_READ_HELD(rwlp) ((RW_COUNT(rwlp) > 0) ? RW_COUNT(rwlp) : 0)
# define RW_WRITE_HELD(rwlp) ((RW_COUNT(rwlp) < 0))
# define rw_exit_locked(rwlp) up_read(rwlp)
# define rw_tryenter_locked(rwlp) down_write_trylock(rwlp)
#endif
#define rw_tryenter(rwlp, rw) \
({ \
int _rc_ = 0; \
switch (rw) { \
case RW_READER: _rc_ = down_read_trylock(rwlp); break; \
case RW_WRITER: _rc_ = down_write_trylock(rwlp); break; \
default: SBUG(); \
} \
_rc_; \
})
#define rw_enter(rwlp, rw) \
({ \
switch (rw) { \
case RW_READER: down_read(rwlp); break; \
case RW_WRITER: down_write(rwlp); break; \
default: SBUG(); \
} \
})
#define rw_exit(rwlp) \
({ \
if (RW_READ_HELD(rwlp)) \
up_read(rwlp); \
else if (RW_WRITE_HELD(rwlp)) \
up_write(rwlp); \
else \
SBUG(); \
})
#define rw_tryupgrade(rwlp) \
({ \
unsigned long flags; \
int _rc_ = 0; \
spin_lock_irqsave(&(rwlp)->wait_lock, flags); \
if (list_empty(&(rwlp)->wait_list) && (RW_READ_HELD(rwlp) == 1)) { \
rw_exit_locked(rwlp); \
_rc_ = rw_tryenter_locked(rwlp); \
ASSERT(_rc_); \
} \
spin_unlock_irqrestore(&(rwlp)->wait_lock, flags); \
_rc_; \
})
#endif /* _SPL_RWLOCK_H */
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