1 files changed, 149 insertions, 0 deletions
diff --git a/arch/mn10300/kernel/semaphore.c b/arch/mn10300/kernel/semaphore.c
new file mode 100644
index 0000000..9153c40
--- /dev/null
+++ b/arch/mn10300/kernel/semaphore.c
@@ -0,0 +1,149 @@
+/* MN10300 Semaphore implementation
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <asm/semaphore.h>
+
+struct sem_waiter {
+	struct list_head	list;
+	struct task_struct	*task;
+};
+
+#if SEMAPHORE_DEBUG
+void semtrace(struct semaphore *sem, const char *str)
+{
+	if (sem->debug)
+		printk(KERN_DEBUG "[%d] %s({%d,%d})\n",
+		       current->pid,
+		       str,
+		       atomic_read(&sem->count),
+		       list_empty(&sem->wait_list) ? 0 : 1);
+}
+#else
+#define semtrace(SEM, STR) do { } while (0)
+#endif
+
+/*
+ * wait for a token to be granted from a semaphore
+ * - entered with lock held and interrupts disabled
+ */
+void __down(struct semaphore *sem, unsigned long flags)
+{
+	struct task_struct *tsk = current;
+	struct sem_waiter waiter;
+
+	semtrace(sem, "Entering __down");
+
+	/* set up my own style of waitqueue */
+	waiter.task = tsk;
+	get_task_struct(tsk);
+
+	list_add_tail(&waiter.list, &sem->wait_list);
+
+	/* we don't need to touch the semaphore struct anymore */
+	spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	/* wait to be given the semaphore */
+	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+
+	for (;;) {
+		if (!waiter.task)
+			break;
+		schedule();
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+	}
+
+	tsk->state = TASK_RUNNING;
+	semtrace(sem, "Leaving __down");
+}
+EXPORT_SYMBOL(__down);
+
+/*
+ * interruptibly wait for a token to be granted from a semaphore
+ * - entered with lock held and interrupts disabled
+ */
+int __down_interruptible(struct semaphore *sem, unsigned long flags)
+{
+	struct task_struct *tsk = current;
+	struct sem_waiter waiter;
+	int ret;
+
+	semtrace(sem, "Entering __down_interruptible");
+
+	/* set up my own style of waitqueue */
+	waiter.task = tsk;
+	get_task_struct(tsk);
+
+	list_add_tail(&waiter.list, &sem->wait_list);
+
+	/* we don't need to touch the semaphore struct anymore */
+	set_task_state(tsk, TASK_INTERRUPTIBLE);
+
+	spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	/* wait to be given the semaphore */
+	ret = 0;
+	for (;;) {
+		if (!waiter.task)
+			break;
+		if (unlikely(signal_pending(current)))
+			goto interrupted;
+		schedule();
+		set_task_state(tsk, TASK_INTERRUPTIBLE);
+	}
+
+ out:
+	tsk->state = TASK_RUNNING;
+	semtrace(sem, "Leaving __down_interruptible");
+	return ret;
+
+ interrupted:
+	spin_lock_irqsave(&sem->wait_lock, flags);
+	list_del(&waiter.list);
+	spin_unlock_irqrestore(&sem->wait_lock, flags);
+
+	ret = 0;
+	if (!waiter.task) {
+		put_task_struct(current);
+		ret = -EINTR;
+	}
+	goto out;
+}
+EXPORT_SYMBOL(__down_interruptible);
+
+/*
+ * release a single token back to a semaphore
+ * - entered with lock held and interrupts disabled
+ */
+void __up(struct semaphore *sem)
+{
+	struct task_struct *tsk;
+	struct sem_waiter *waiter;
+
+	semtrace(sem, "Entering __up");
+
+	/* grant the token to the process at the front of the queue */
+	waiter = list_entry(sem->wait_list.next, struct sem_waiter, list);
+
+	/* We must be careful not to touch 'waiter' after we set ->task = NULL.
+	 * It is an allocated on the waiter's stack and may become invalid at
+	 * any time after that point (due to a wakeup from another source).
+	 */
+	list_del_init(&waiter->list);
+	tsk = waiter->task;
+	smp_mb();
+	waiter->task = NULL;
+	wake_up_process(tsk);
+	put_task_struct(tsk);
+
+	semtrace(sem, "Leaving __up");
+}
+EXPORT_SYMBOL(__up);