Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 224 insertions, 0 deletions

diff --git a/arch/alpha/kernel/semaphore.c b/arch/alpha/kernel/semaphore.c
new file mode 100644
index 00000000000..8c8aaa205ea
--- /dev/null
+++ b/arch/alpha/kernel/semaphore.c
@@ -0,0 +1,224 @@
+/*
+ * Alpha semaphore implementation.
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ * (C) Copyright 1999, 2000 Richard Henderson
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+
+/*
+ * This is basically the PPC semaphore scheme ported to use
+ * the Alpha ll/sc sequences, so see the PPC code for
+ * credits.
+ */
+
+/*
+ * Atomically update sem->count.
+ * This does the equivalent of the following:
+ *
+ *	old_count = sem->count;
+ *	tmp = MAX(old_count, 0) + incr;
+ *	sem->count = tmp;
+ *	return old_count;
+ */
+static inline int __sem_update_count(struct semaphore *sem, int incr)
+{
+	long old_count, tmp = 0;
+
+	__asm__ __volatile__(
+	"1:	ldl_l	%0,%2\n"
+	"	cmovgt	%0,%0,%1\n"
+	"	addl	%1,%3,%1\n"
+	"	stl_c	%1,%2\n"
+	"	beq	%1,2f\n"
+	"	mb\n"
+	".subsection 2\n"
+	"2:	br	1b\n"
+	".previous"
+	: "=&r" (old_count), "=&r" (tmp), "=m" (sem->count)
+	: "Ir" (incr), "1" (tmp), "m" (sem->count));
+
+	return old_count;
+}
+
+/*
+ * Perform the "down" function.  Return zero for semaphore acquired,
+ * return negative for signalled out of the function.
+ *
+ * If called from down, the return is ignored and the wait loop is
+ * not interruptible.  This means that a task waiting on a semaphore
+ * using "down()" cannot be killed until someone does an "up()" on
+ * the semaphore.
+ *
+ * If called from down_interruptible, the return value gets checked
+ * upon return.  If the return value is negative then the task continues
+ * with the negative value in the return register (it can be tested by
+ * the caller).
+ *
+ * Either form may be used in conjunction with "up()".
+ */
+
+void __sched
+__down_failed(struct semaphore *sem)
+{
+	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down failed(%p)\n",
+	       tsk->comm, tsk->pid, sem);
+#endif
+
+	tsk->state = TASK_UNINTERRUPTIBLE;
+	wmb();
+	add_wait_queue_exclusive(&sem->wait, &wait);
+
+	/*
+	 * Try to get the semaphore.  If the count is > 0, then we've
+	 * got the semaphore; we decrement count and exit the loop.
+	 * If the count is 0 or negative, we set it to -1, indicating
+	 * that we are asleep, and then sleep.
+	 */
+	while (__sem_update_count(sem, -1) <= 0) {
+		schedule();
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+	}
+	remove_wait_queue(&sem->wait, &wait);
+	tsk->state = TASK_RUNNING;
+
+	/*
+	 * If there are any more sleepers, wake one of them up so
+	 * that it can either get the semaphore, or set count to -1
+	 * indicating that there are still processes sleeping.
+	 */
+	wake_up(&sem->wait);
+
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down acquired(%p)\n",
+	       tsk->comm, tsk->pid, sem);
+#endif
+}
+
+int __sched
+__down_failed_interruptible(struct semaphore *sem)
+{
+	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+	long ret = 0;
+
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down failed(%p)\n",
+	       tsk->comm, tsk->pid, sem);
+#endif
+
+	tsk->state = TASK_INTERRUPTIBLE;
+	wmb();
+	add_wait_queue_exclusive(&sem->wait, &wait);
+
+	while (__sem_update_count(sem, -1) <= 0) {
+		if (signal_pending(current)) {
+			/*
+			 * A signal is pending - give up trying.
+			 * Set sem->count to 0 if it is negative,
+			 * since we are no longer sleeping.
+			 */
+			__sem_update_count(sem, 0);
+			ret = -EINTR;
+			break;
+		}
+		schedule();
+		set_task_state(tsk, TASK_INTERRUPTIBLE);
+	}
+
+	remove_wait_queue(&sem->wait, &wait);
+	tsk->state = TASK_RUNNING;
+	wake_up(&sem->wait);
+
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down %s(%p)\n",
+	       current->comm, current->pid,
+	       (ret < 0 ? "interrupted" : "acquired"), sem);
+#endif
+	return ret;
+}
+
+void
+__up_wakeup(struct semaphore *sem)
+{
+	/*
+	 * Note that we incremented count in up() before we came here,
+	 * but that was ineffective since the result was <= 0, and
+	 * any negative value of count is equivalent to 0.
+	 * This ends up setting count to 1, unless count is now > 0
+	 * (i.e. because some other cpu has called up() in the meantime),
+	 * in which case we just increment count.
+	 */
+	__sem_update_count(sem, 1);
+	wake_up(&sem->wait);
+}
+
+void __sched
+down(struct semaphore *sem)
+{
+#ifdef WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down(%p) <count=%d> from %p\n",
+	       current->comm, current->pid, sem,
+	       atomic_read(&sem->count), __builtin_return_address(0));
+#endif
+	__down(sem);
+}
+
+int __sched
+down_interruptible(struct semaphore *sem)
+{
+#ifdef WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down(%p) <count=%d> from %p\n",
+	       current->comm, current->pid, sem,
+	       atomic_read(&sem->count), __builtin_return_address(0));
+#endif
+	return __down_interruptible(sem);
+}
+
+int
+down_trylock(struct semaphore *sem)
+{
+	int ret;
+
+#ifdef WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+
+	ret = __down_trylock(sem);
+
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): down_trylock %s from %p\n",
+	       current->comm, current->pid,
+	       ret ? "failed" : "acquired",
+	       __builtin_return_address(0));
+#endif
+
+	return ret;
+}
+
+void
+up(struct semaphore *sem)
+{
+#ifdef WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+#ifdef CONFIG_DEBUG_SEMAPHORE
+	printk("%s(%d): up(%p) <count=%d> from %p\n",
+	       current->comm, current->pid, sem,
+	       atomic_read(&sem->count), __builtin_return_address(0));
+#endif
+	__up(sem);
+}