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Added new mutex_switch_from_read_lock() for unlocking a read lock and

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starting to lock a mutex in an atomic operation.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34935 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2010-01-07 15:31:29 +00:00
parent 8ab820f076
commit c4f9831292
3 changed files with 55 additions and 11 deletions
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16
headers/private/kernel/lock.h
View File

@ -124,7 +124,6 @@ extern void rw_lock_init(rw_lock* lock, const char* name);
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 rw_lock_write_unlock(rw_lock* lock);
extern void mutex_init(mutex* lock, const char* name);
// name is *not* cloned nor freed in mutex_destroy()
@ -135,12 +134,16 @@ extern status_t mutex_switch_lock(mutex* from, mutex* to);
// 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 void _rw_lock_read_unlock(rw_lock* lock);
extern void _rw_lock_read_unlock(rw_lock* lock, bool threadsLocked);
extern void _rw_lock_write_unlock(rw_lock* lock, bool threadsLocked);
extern status_t _mutex_lock(mutex* lock, bool threadsLocked);
extern void _mutex_unlock(mutex* lock, bool threadsLocked);
@ -171,11 +174,18 @@ rw_lock_read_unlock(rw_lock* lock)
#else
int32 oldCount = atomic_add(&lock->count, -1);
if (oldCount >= RW_LOCK_WRITER_COUNT_BASE)
_rw_lock_read_unlock(lock);
_rw_lock_read_unlock(lock, false);
#endif
}
static inline void
rw_lock_write_unlock(rw_lock* lock)
{
_rw_lock_write_unlock(lock, false);
}
static inline status_t
mutex_lock(mutex* lock)
{

25
src/system/kernel/lock.cpp
View File

@ -323,9 +323,9 @@ _rw_lock_read_lock(rw_lock* lock)
void
_rw_lock_read_unlock(rw_lock* lock)
_rw_lock_read_unlock(rw_lock* lock, bool threadsLocked)
{
InterruptsSpinLocker locker(gThreadSpinlock);
InterruptsSpinLocker locker(gThreadSpinlock, false, !threadsLocked);
// If we're still holding the write lock or if there are other readers,
// no-one can be woken up.
@ -389,9 +389,9 @@ rw_lock_write_lock(rw_lock* lock)
void
rw_lock_write_unlock(rw_lock* lock)
_rw_lock_write_unlock(rw_lock* lock, bool threadsLocked)
{
InterruptsSpinLocker locker(gThreadSpinlock);
InterruptsSpinLocker locker(gThreadSpinlock, false, !threadsLocked);
if (thread_get_current_thread_id() != lock->holder) {
panic("rw_lock_write_unlock(): lock %p not write-locked by this thread",
@ -558,6 +558,23 @@ mutex_switch_lock(mutex* from, mutex* to)
}
status_t
mutex_switch_from_read_lock(rw_lock* from, mutex* to)
{
InterruptsSpinLocker locker(gThreadSpinlock);
#if KDEBUG_RW_LOCK_DEBUG
_rw_lock_write_unlock(from, true);
#else
int32 oldCount = atomic_add(&from->count, -1);
if (oldCount >= RW_LOCK_WRITER_COUNT_BASE)
_rw_lock_read_unlock(from, true);
#endif
return mutex_lock_threads_locked(to);
}
status_t
_mutex_lock(mutex* lock, bool threadsLocked)
{

25
src/tests/add-ons/kernel/kernelland_emu/lock.cpp
View File

@ -360,9 +360,9 @@ _rw_lock_read_lock(rw_lock* lock)
void
_rw_lock_read_unlock(rw_lock* lock)
_rw_lock_read_unlock(rw_lock* lock, bool threadsLocked)
{
AutoLocker<ThreadSpinlock> locker(sThreadSpinlock);
AutoLocker<ThreadSpinlock> locker(sThreadSpinlock, false, !threadsLocked);
// If we're still holding the write lock or if there are other readers,
// no-one can be woken up.
@ -425,9 +425,9 @@ rw_lock_write_lock(rw_lock* lock)
void
rw_lock_write_unlock(rw_lock* lock)
_rw_lock_write_unlock(rw_lock* lock, bool threadsLocked)
{
AutoLocker<ThreadSpinlock> locker(sThreadSpinlock);
AutoLocker<ThreadSpinlock> locker(sThreadSpinlock, false, !threadsLocked);
if (find_thread(NULL) != lock->holder) {
panic("rw_lock_write_unlock(): lock %p not write-locked by this thread",
@ -548,6 +548,23 @@ mutex_switch_lock(mutex* from, mutex* to)
}
status_t
mutex_switch_from_read_lock(rw_lock* from, mutex* to)
{
AutoLocker<ThreadSpinlock> locker(sThreadSpinlock);
#if KDEBUG_RW_LOCK_DEBUG
_rw_lock_write_unlock(from, true);
#else
int32 oldCount = atomic_add(&from->count, -1);
if (oldCount >= RW_LOCK_WRITER_COUNT_BASE)
_rw_lock_read_unlock(from, true);
#endif
return mutex_lock_threads_locked(to);
}
status_t
_mutex_lock(mutex* lock, bool threadsLocked)
{