/*
* 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://zfsonlinux.org/>.
*
* 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>
#include <linux/sched.h>
/* Linux kernel compatibility */
#if defined(CONFIG_PREEMPT_RT_FULL)
#define SPL_RWSEM_SINGLE_READER_VALUE (1)
#define SPL_RWSEM_SINGLE_WRITER_VALUE (0)
#elif defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
#define SPL_RWSEM_SINGLE_READER_VALUE (1)
#define SPL_RWSEM_SINGLE_WRITER_VALUE (-1)
#else
#define SPL_RWSEM_SINGLE_READER_VALUE (RWSEM_ACTIVE_READ_BIAS)
#define SPL_RWSEM_SINGLE_WRITER_VALUE (RWSEM_ACTIVE_WRITE_BIAS)
#endif
/* Linux 3.16 changed activity to count for rwsem-spinlock */
#if defined(CONFIG_PREEMPT_RT_FULL)
#define RWSEM_COUNT(sem) sem->read_depth
#elif defined(HAVE_RWSEM_ACTIVITY)
#define RWSEM_COUNT(sem) sem->activity
/* Linux 4.8 changed count to an atomic_long_t for !rwsem-spinlock */
#elif defined(HAVE_RWSEM_ATOMIC_LONG_COUNT)
#define RWSEM_COUNT(sem) atomic_long_read(&(sem)->count)
#else
#define RWSEM_COUNT(sem) sem->count
#endif
#if defined(RWSEM_SPINLOCK_IS_RAW)
#define spl_rwsem_lock_irqsave(lk, fl) raw_spin_lock_irqsave(lk, fl)
#define spl_rwsem_unlock_irqrestore(lk, fl) \
raw_spin_unlock_irqrestore(lk, fl)
#define spl_rwsem_trylock_irqsave(lk, fl) raw_spin_trylock_irqsave(lk, fl)
#else
#define spl_rwsem_lock_irqsave(lk, fl) spin_lock_irqsave(lk, fl)
#define spl_rwsem_unlock_irqrestore(lk, fl) spin_unlock_irqrestore(lk, fl)
#define spl_rwsem_trylock_irqsave(lk, fl) spin_trylock_irqsave(lk, fl)
#endif /* RWSEM_SPINLOCK_IS_RAW */
#define spl_rwsem_is_locked(rwsem) rwsem_is_locked(rwsem)
typedef enum {
RW_DRIVER = 2,
RW_DEFAULT = 4,
RW_NOLOCKDEP = 5
} krw_type_t;
typedef enum {
RW_NONE = 0,
RW_WRITER = 1,
RW_READER = 2
} krw_t;
/*
* If CONFIG_RWSEM_SPIN_ON_OWNER is defined, rw_semaphore will have an owner
* field, so we don't need our own.
*/
typedef struct {
struct rw_semaphore rw_rwlock;
#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
kthread_t *rw_owner;
#endif
#ifdef CONFIG_LOCKDEP
krw_type_t rw_type;
#endif /* CONFIG_LOCKDEP */
} krwlock_t;
#define SEM(rwp) (&(rwp)->rw_rwlock)
static inline void
spl_rw_set_owner(krwlock_t *rwp)
{
/*
* If CONFIG_RWSEM_SPIN_ON_OWNER is defined, down_write, up_write,
* downgrade_write and __init_rwsem will set/clear owner for us.
*/
#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
rwp->rw_owner = current;
#endif
}
static inline void
spl_rw_clear_owner(krwlock_t *rwp)
{
#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
rwp->rw_owner = NULL;
#endif
}
static inline kthread_t *
rw_owner(krwlock_t *rwp)
{
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
return (SEM(rwp)->owner);
#else
return (rwp->rw_owner);
#endif
}
#ifdef CONFIG_LOCKDEP
static inline void
spl_rw_set_type(krwlock_t *rwp, krw_type_t type)
{
rwp->rw_type = type;
}
static inline void
spl_rw_lockdep_off_maybe(krwlock_t *rwp) \
{ \
if (rwp && rwp->rw_type == RW_NOLOCKDEP) \
lockdep_off(); \
}
static inline void
spl_rw_lockdep_on_maybe(krwlock_t *rwp) \
{ \
if (rwp && rwp->rw_type == RW_NOLOCKDEP) \
lockdep_on(); \
}
#else /* CONFIG_LOCKDEP */
#define spl_rw_set_type(rwp, type)
#define spl_rw_lockdep_off_maybe(rwp)
#define spl_rw_lockdep_on_maybe(rwp)
#endif /* CONFIG_LOCKDEP */
static inline int
RW_READ_HELD(krwlock_t *rwp)
{
/*
* Linux 4.8 will set owner to 1 when read held instead of leave it
* NULL. So we check whether owner <= 1.
*/
return (spl_rwsem_is_locked(SEM(rwp)) &&
(unsigned long)rw_owner(rwp) <= 1);
}
static inline int
RW_WRITE_HELD(krwlock_t *rwp)
{
return (rw_owner(rwp) == current);
}
static inline int
RW_LOCK_HELD(krwlock_t *rwp)
{
return (spl_rwsem_is_locked(SEM(rwp)));
}
/*
* 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
*/
/* BEGIN CSTYLED */
#define rw_init(rwp, name, type, arg) \
({ \
static struct lock_class_key __key; \
ASSERT(type == RW_DEFAULT || type == RW_NOLOCKDEP); \
\
__init_rwsem(SEM(rwp), #rwp, &__key); \
spl_rw_clear_owner(rwp); \
spl_rw_set_type(rwp, type); \
})
/*
* The Linux rwsem implementation does not require a matching destroy.
*/
#define rw_destroy(rwp) ((void) 0)
#define rw_tryenter(rwp, rw) \
({ \
int _rc_ = 0; \
\
spl_rw_lockdep_off_maybe(rwp); \
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: \
VERIFY(0); \
} \
spl_rw_lockdep_on_maybe(rwp); \
_rc_; \
})
#define rw_enter(rwp, rw) \
({ \
spl_rw_lockdep_off_maybe(rwp); \
switch (rw) { \
case RW_READER: \
down_read(SEM(rwp)); \
break; \
case RW_WRITER: \
down_write(SEM(rwp)); \
spl_rw_set_owner(rwp); \
break; \
default: \
VERIFY(0); \
} \
spl_rw_lockdep_on_maybe(rwp); \
})
#define rw_exit(rwp) \
({ \
spl_rw_lockdep_off_maybe(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)); \
} \
spl_rw_lockdep_on_maybe(rwp); \
})
#define rw_downgrade(rwp) \
({ \
spl_rw_lockdep_off_maybe(rwp); \
spl_rw_clear_owner(rwp); \
downgrade_write(SEM(rwp)); \
spl_rw_lockdep_on_maybe(rwp); \
})
#define rw_tryupgrade(rwp) \
({ \
int _rc_ = 0; \
\
if (RW_WRITE_HELD(rwp)) { \
_rc_ = 1; \
} else { \
spl_rw_lockdep_off_maybe(rwp); \
if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \
spl_rw_set_owner(rwp); \
spl_rw_lockdep_on_maybe(rwp); \
} \
_rc_; \
})
/* END CSTYLED */
int spl_rw_init(void);
void spl_rw_fini(void);
int rwsem_tryupgrade(struct rw_semaphore *rwsem);
#endif /* _SPL_RWLOCK_H */