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haiku/headers/private/kernel/lock.h
Michael Lotz 57656b93b6 kernel/locks: Implement lock switching for recursive_lock. 
This allows switching from another recursive_lock, mutex or read-locked
rw_lock analogous to the switching possibilities already in mutex.

With this, recursive_locks can be used in more complex situations where
previously only mutexes would work.

Also add debugger command to dump a recursive_lock.

Change-Id: Ibeeae1b42c543d925dec61a3b257e1f3df7f8934
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2834
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
2020-05-30 01:47:40 +00:00

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/*
* Copyright 2008-2011, Ingo Weinhold, ingo_weinhold@gmx.de.
* Copyright 2002-2009, Axel Dörfler, axeld@pinc-software.de.
* Distributed under the terms of the MIT License.
*
* Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
* Distributed under the terms of the NewOS License.
*/
#ifndef _KERNEL_LOCK_H
#define _KERNEL_LOCK_H
#include <OS.h>
#include <arch/atomic.h>
#include <debug.h>
struct mutex_waiter;
typedef struct mutex {
const char* name;
struct mutex_waiter* waiters;
spinlock lock;
#if KDEBUG
thread_id holder;
#else
int32 count;
#endif
uint8 flags;
} mutex;
#define MUTEX_FLAG_CLONE_NAME 0x1
typedef struct recursive_lock {
mutex lock;
#if !KDEBUG
thread_id holder;
#else
int32 _unused;
#endif
int recursion;
} recursive_lock;
struct rw_lock_waiter;
typedef struct rw_lock {
const char* name;
struct rw_lock_waiter* waiters;
spinlock lock;
thread_id holder;
int32 count;
int32 owner_count;
int16 active_readers;
// Only > 0 while a writer is waiting: number
// of active readers when the first waiting
// writer started waiting.
int16 pending_readers;
// Number of readers that have already
// incremented "count", but have not yet started
// to wait at the time the last writer unlocked.
uint32 flags;
} rw_lock;
#define RW_LOCK_WRITER_COUNT_BASE 0x10000
#define RW_LOCK_FLAG_CLONE_NAME 0x1
#if KDEBUG
# define KDEBUG_RW_LOCK_DEBUG 0
// Define to 1 if you want to use ASSERT_READ_LOCKED_RW_LOCK().
// The rw_lock will just behave like a recursive locker then.
# define ASSERT_LOCKED_RECURSIVE(r) \
{ ASSERT(find_thread(NULL) == (r)->lock.holder); }
# define ASSERT_LOCKED_MUTEX(m) { ASSERT(find_thread(NULL) == (m)->holder); }
# define ASSERT_WRITE_LOCKED_RW_LOCK(l) \
{ ASSERT(find_thread(NULL) == (l)->holder); }
# if KDEBUG_RW_LOCK_DEBUG
# define ASSERT_READ_LOCKED_RW_LOCK(l) \
{ ASSERT(find_thread(NULL) == (l)->holder); }
# else
# define ASSERT_READ_LOCKED_RW_LOCK(l) do {} while (false)
# endif
#else
# define ASSERT_LOCKED_RECURSIVE(r) do {} while (false)
# define ASSERT_LOCKED_MUTEX(m) do {} while (false)
# define ASSERT_WRITE_LOCKED_RW_LOCK(m) do {} while (false)
# define ASSERT_READ_LOCKED_RW_LOCK(l) do {} while (false)
#endif
// static initializers
#if KDEBUG
# define MUTEX_INITIALIZER(name) \
{ name, NULL, B_SPINLOCK_INITIALIZER, -1, 0 }
# define RECURSIVE_LOCK_INITIALIZER(name) { MUTEX_INITIALIZER(name), 0 }
#else
# define MUTEX_INITIALIZER(name) \
{ name, NULL, B_SPINLOCK_INITIALIZER, 0, 0 }
# define RECURSIVE_LOCK_INITIALIZER(name) { MUTEX_INITIALIZER(name), -1, 0 }
#endif
#define RW_LOCK_INITIALIZER(name) \
{ name, NULL, B_SPINLOCK_INITIALIZER, -1, 0, 0, 0, 0, 0 }
#if KDEBUG
# define RECURSIVE_LOCK_HOLDER(recursiveLock) ((recursiveLock)->lock.holder)
#else
# define RECURSIVE_LOCK_HOLDER(recursiveLock) ((recursiveLock)->holder)
#endif
#ifdef __cplusplus
extern "C" {
#endif
extern void recursive_lock_init(recursive_lock *lock, const char *name);
// name is *not* cloned nor freed in recursive_lock_destroy()
extern void recursive_lock_init_etc(recursive_lock *lock, const char *name,
uint32 flags);
extern void recursive_lock_destroy(recursive_lock *lock);
extern status_t recursive_lock_lock(recursive_lock *lock);
extern status_t recursive_lock_trylock(recursive_lock *lock);
extern void recursive_lock_unlock(recursive_lock *lock);
extern status_t recursive_lock_switch_lock(recursive_lock* from,
recursive_lock* to);
// Unlocks "from" and locks "to" such that unlocking and starting to wait
// for the lock is atomic. I.e. if "from" guards the object "to" belongs
// to, the operation is safe as long as "from" is held while destroying
// "to".
extern status_t recursive_lock_switch_from_mutex(mutex* from,
recursive_lock* to);
// Like recursive_lock_switch_lock(), just for switching from a mutex.
extern status_t recursive_lock_switch_from_read_lock(rw_lock* from,
recursive_lock* to);
// Like recursive_lock_switch_lock(), just for switching from a read-locked
// rw_lock.
extern int32 recursive_lock_get_recursion(recursive_lock *lock);
extern void rw_lock_init(rw_lock* lock, const char* name);
// name is *not* cloned nor freed in rw_lock_destroy()
extern void rw_lock_init_etc(rw_lock* lock, const char* name, uint32 flags);
extern void rw_lock_destroy(rw_lock* lock);
extern status_t rw_lock_write_lock(rw_lock* lock);
extern void mutex_init(mutex* lock, const char* name);
// name is *not* cloned nor freed in mutex_destroy()
extern void mutex_init_etc(mutex* lock, const char* name, uint32 flags);
extern void mutex_destroy(mutex* lock);
extern void mutex_transfer_lock(mutex* lock, thread_id thread);
extern status_t mutex_switch_lock(mutex* from, mutex* to);
// Unlocks "from" and locks "to" such that unlocking and starting to wait
// for the lock is atomically. I.e. if "from" guards the object "to" belongs
// to, the operation is safe as long as "from" is held while destroying
// "to".
extern status_t mutex_switch_from_read_lock(rw_lock* from, mutex* to);
// Like mutex_switch_lock(), just for a switching from a read-locked
// rw_lock.
// implementation private:
extern status_t _rw_lock_read_lock(rw_lock* lock);
extern status_t _rw_lock_read_lock_with_timeout(rw_lock* lock,
uint32 timeoutFlags, bigtime_t timeout);
extern void _rw_lock_read_unlock(rw_lock* lock);
extern void _rw_lock_write_unlock(rw_lock* lock);
extern status_t _mutex_lock(mutex* lock, void* locker);
extern void _mutex_unlock(mutex* lock);
extern status_t _mutex_trylock(mutex* lock);
extern status_t _mutex_lock_with_timeout(mutex* lock, uint32 timeoutFlags,
bigtime_t timeout);
static inline status_t
rw_lock_read_lock(rw_lock* lock)
{
#if KDEBUG_RW_LOCK_DEBUG
return rw_lock_write_lock(lock);
#else
int32 oldCount = atomic_add(&lock->count, 1);
if (oldCount >= RW_LOCK_WRITER_COUNT_BASE)
return _rw_lock_read_lock(lock);
return B_OK;
#endif
}
static inline status_t
rw_lock_read_lock_with_timeout(rw_lock* lock, uint32 timeoutFlags,
bigtime_t timeout)
{
#if KDEBUG_RW_LOCK_DEBUG
return mutex_lock_with_timeout(lock, timeoutFlags, timeout);
#else
int32 oldCount = atomic_add(&lock->count, 1);
if (oldCount >= RW_LOCK_WRITER_COUNT_BASE)
return _rw_lock_read_lock_with_timeout(lock, timeoutFlags, timeout);
return B_OK;
#endif
}
static inline void
rw_lock_read_unlock(rw_lock* lock)
{
#if KDEBUG_RW_LOCK_DEBUG
rw_lock_write_unlock(lock);
#else
int32 oldCount = atomic_add(&lock->count, -1);
if (oldCount >= RW_LOCK_WRITER_COUNT_BASE)
_rw_lock_read_unlock(lock);
#endif
}
static inline void
rw_lock_write_unlock(rw_lock* lock)
{
_rw_lock_write_unlock(lock);
}
static inline status_t
mutex_lock(mutex* lock)
{
#if KDEBUG
return _mutex_lock(lock, NULL);
#else
if (atomic_add(&lock->count, -1) < 0)
return _mutex_lock(lock, NULL);
return B_OK;
#endif
}
static inline status_t
mutex_trylock(mutex* lock)
{
#if KDEBUG
return _mutex_trylock(lock);
#else
if (atomic_test_and_set(&lock->count, -1, 0) != 0)
return B_WOULD_BLOCK;
return B_OK;
#endif
}
static inline status_t
mutex_lock_with_timeout(mutex* lock, uint32 timeoutFlags, bigtime_t timeout)
{
#if KDEBUG
return _mutex_lock_with_timeout(lock, timeoutFlags, timeout);
#else
if (atomic_add(&lock->count, -1) < 0)
return _mutex_lock_with_timeout(lock, timeoutFlags, timeout);
return B_OK;
#endif
}
static inline void
mutex_unlock(mutex* lock)
{
#if !KDEBUG
if (atomic_add(&lock->count, 1) < -1)
#endif
_mutex_unlock(lock);
}
static inline void
recursive_lock_transfer_lock(recursive_lock* lock, thread_id thread)
{
if (lock->recursion != 1)
panic("invalid recursion level for lock transfer!");
#if KDEBUG
mutex_transfer_lock(&lock->lock, thread);
#else
lock->holder = thread;
#endif
}
extern void lock_debug_init();
#ifdef __cplusplus
}
#endif
#endif /* _KERNEL_LOCK_H */
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