* Reverted r33643 - while it doubled the performance for my test case (with

high contention of the read lock (I experimented with the VM page mapping
  lock)), it actually hurt the compile performance pretty obviously.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@33647 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/lock.h

@@ -42,7 +42,6 @@ struct rw_lock_waiter;
 
 typedef struct rw_lock {
 	const char*				name;
-	mutex					lock;
 	struct rw_lock_waiter*	waiters;
 	thread_id				holder;
 	int32					reader_count;
@@ -86,8 +85,7 @@ typedef struct rw_lock {
 #	define RECURSIVE_LOCK_INITIALIZER(name)	{ MUTEX_INITIALIZER(name), -1, 0 }
 #endif
 
-#define RW_LOCK_INITIALIZER(name)			{ name, MUTEX_INITIALIZER(name), \
+#define RW_LOCK_INITIALIZER(name)			{ name, NULL, -1, 0, 0, 0 }
-												NULL, -1, 0, 0, 0 }
 
 
 #if KDEBUG

src/system/kernel/lock.cpp

@@ -164,10 +164,6 @@ rw_lock_wait(rw_lock* lock, bool writer)
 
 	lock->waiters->last = &waiter;
 
-	InterruptsSpinLocker locker(gThreadSpinlock);
-
-	_mutex_unlock(&lock->lock, true);
-
 	// block
 	thread_prepare_to_block(waiter.thread, 0, THREAD_BLOCK_TYPE_RW_LOCK, lock);
 	return thread_block_locked(waiter.thread);
@@ -194,7 +190,6 @@ rw_lock_unblock(rw_lock* lock)
 			lock->holder = waiter->thread->id;
 
 			// unblock thread
-			InterruptsSpinLocker locker(gThreadSpinlock);
 			thread_unblock_locked(waiter->thread, B_OK);
 		}
 		return;
@@ -210,7 +205,6 @@ rw_lock_unblock(rw_lock* lock)
 		lock->reader_count++;
 
 		// unblock thread
-		InterruptsSpinLocker locker(gThreadSpinlock);
 		thread_unblock_locked(waiter->thread, B_OK);
 	}
 }
@@ -227,8 +221,6 @@ rw_lock_init(rw_lock* lock, const char* name)
 	lock->owner_count = 0;
 	lock->flags = 0;
 
-	mutex_init(&lock->lock, name);
-
 	T_SCHEDULING_ANALYSIS(InitRWLock(lock, name));
 	NotifyWaitObjectListeners(&WaitObjectListener::RWLockInitialized, lock);
 }
@@ -245,8 +237,6 @@ rw_lock_init_etc(rw_lock* lock, const char* name, uint32 flags)
 	lock->owner_count = 0;
 	lock->flags = flags & RW_LOCK_FLAG_CLONE_NAME;
 
-	mutex_init(&lock->lock, lock->name);
-
 	T_SCHEDULING_ANALYSIS(InitRWLock(lock, name));
 	NotifyWaitObjectListeners(&WaitObjectListener::RWLockInitialized, lock);
 }
@@ -262,8 +252,8 @@ rw_lock_destroy(rw_lock* lock)
 	InterruptsSpinLocker locker(gThreadSpinlock);
 
 #if KDEBUG
-	if (lock->waiters != NULL
+	if (lock->waiters != NULL && thread_get_current_thread_id()
-		&& thread_get_current_thread_id() != lock->holder) {
+		!= lock->holder) {
 		panic("rw_lock_destroy(): there are blocking threads, but the caller "
 			"doesn't hold the write lock (%p)", lock);
 
@@ -285,7 +275,6 @@ rw_lock_destroy(rw_lock* lock)
 	lock->name = NULL;
 
 	locker.Unlock();
-	mutex_destroy(&lock->lock);
 
 	free(name);
 }
@@ -297,7 +286,7 @@ rw_lock_read_lock(rw_lock* lock)
 #if KDEBUG_RW_LOCK_DEBUG
 	return rw_lock_write_lock(lock);
 #else
-	MutexLocker locker(lock->lock);
+	InterruptsSpinLocker locker(gThreadSpinlock);
 
 	if (lock->writer_count == 0) {
 		lock->reader_count++;
@@ -308,8 +297,6 @@ rw_lock_read_lock(rw_lock* lock)
 		return B_OK;
 	}
 
-	locker.Detach();
-
 	return rw_lock_wait(lock, false);
 #endif
 }
@@ -321,7 +308,7 @@ rw_lock_read_unlock(rw_lock* lock)
 #if KDEBUG_RW_LOCK_DEBUG
 	return rw_lock_write_unlock(lock);
 #else
-	MutexLocker locker(lock->lock);
+	InterruptsSpinLocker locker(gThreadSpinlock);
 
 	if (lock->holder == thread_get_current_thread_id()) {
 		if (--lock->owner_count > 0)
@@ -351,7 +338,7 @@ rw_lock_read_unlock(rw_lock* lock)
 status_t
 rw_lock_write_lock(rw_lock* lock)
 {
-	MutexLocker locker(lock->lock);
+	InterruptsSpinLocker locker(gThreadSpinlock);
 
 	if (lock->reader_count == 0 && lock->writer_count == 0) {
 		lock->writer_count++;
@@ -365,7 +352,6 @@ rw_lock_write_lock(rw_lock* lock)
 	}
 
 	lock->writer_count++;
-	locker.Detach();
 
 	status_t status = rw_lock_wait(lock, true);
 	if (status == B_OK) {
@@ -379,7 +365,7 @@ rw_lock_write_lock(rw_lock* lock)
 status_t
 rw_lock_write_unlock(rw_lock* lock)
 {
-	MutexLocker locker(lock->lock);
+	InterruptsSpinLocker locker(gThreadSpinlock);
 
 	if (thread_get_current_thread_id() != lock->holder) {
 		panic("rw_lock_write_unlock(): lock %p not write-locked by this thread",