Linux-2.6.12-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!
diff --git a/arch/alpha/kernel/semaphore.c b/arch/alpha/kernel/semaphore.c
new file mode 100644
index 0000000..8c8aaa2
--- /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);
+}