1 files changed, 111 insertions, 0 deletions
diff --git a/arch/mips/kernel/semaphore.c b/arch/mips/kernel/semaphore.c
index d62b355e1..1f47bd929 100644
--- a/arch/mips/kernel/semaphore.c
+++ b/arch/mips/kernel/semaphore.c
@@ -127,3 +127,114 @@ int __down_trylock(struct semaphore * sem)
 {
 	return waking_non_zero_trylock(sem);
 }
+
+/*
+ * RW Semaphores
+ */
+void
+__down_read(struct rw_semaphore *sem, int count)
+{
+	DOWN_VAR;
+
+ retry_down:
+	if (count < 0) {
+		/* Wait for the lock to become unbiased.  Readers
+		   are non-exclusive.  */
+		
+		/* This takes care of granting the lock.  */
+		up_read(sem);
+
+		add_wait_queue(&sem->wait, &wait);
+		while (atomic_read(&sem->count) < 0) {
+			set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+			if (atomic_read(&sem->count) >= 0)
+				break;
+			schedule();
+		}
+
+		remove_wait_queue(&sem->wait, &wait);
+		tsk->state = TASK_RUNNING;
+
+		mb();
+		count = atomic_dec_return(&sem->count);
+		if (count <= 0)
+			goto retry_down;
+	} else {
+		add_wait_queue(&sem->wait, &wait);
+
+		while (1) {
+			if (test_and_clear_bit(0, &sem->granted))
+				break;
+			set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+			if ((sem->granted & 1) == 0)
+				schedule();
+		}
+
+		remove_wait_queue(&sem->wait, &wait);
+		tsk->state = TASK_RUNNING;
+	}
+}
+
+void
+__down_write(struct rw_semaphore *sem, int count)
+{
+	DOWN_VAR;
+
+ retry_down:
+	if (count + RW_LOCK_BIAS < 0) {
+		up_write(sem);
+
+		add_wait_queue_exclusive(&sem->wait, &wait);
+	
+		while (atomic_read(&sem->count) < 0) {
+			set_task_state(tsk, (TASK_UNINTERRUPTIBLE
+					     | TASK_EXCLUSIVE));
+			if (atomic_read(&sem->count) >= RW_LOCK_BIAS)
+				break;
+			schedule();
+		}
+
+		remove_wait_queue(&sem->wait, &wait);
+		tsk->state = TASK_RUNNING;
+
+		mb();
+		count = atomic_sub_return(RW_LOCK_BIAS, &sem->count);
+		if (count != 0)
+			goto retry_down;
+	} else {
+		/* Put ourselves at the end of the list.  */
+		add_wait_queue_exclusive(&sem->write_bias_wait, &wait);
+
+		while (1) {
+			if (test_and_clear_bit(1, &sem->granted))
+				break;
+			set_task_state(tsk, (TASK_UNINTERRUPTIBLE
+					     | TASK_EXCLUSIVE));
+			if ((sem->granted & 2) == 0)
+				schedule();
+		}
+
+		remove_wait_queue(&sem->write_bias_wait, &wait);
+		tsk->state = TASK_RUNNING;
+
+		/* If the lock is currently unbiased, awaken the sleepers.
+		   FIXME: This wakes up the readers early in a bit of a
+		   stampede -> bad!  */
+		if (atomic_read(&sem->count) >= 0)
+			wake_up(&sem->wait);
+	}
+}
+
+void
+__rwsem_wake(struct rw_semaphore *sem, unsigned long readers)
+{
+	if (readers) {
+		if (test_and_set_bit(0, &sem->granted))
+			BUG();
+		wake_up(&sem->wait);
+	} else {
+		if (test_and_set_bit(1, &sem->granted))
+			BUG();
+		wake_up(&sem->write_bias_wait);
+	}
+}