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/mips/kernel/semaphore.c b/arch/mips/kernel/semaphore.c
new file mode 100644
index 0000000..9c40fe5
--- /dev/null
+++ b/arch/mips/kernel/semaphore.c
@@ -0,0 +1,164 @@
+/*
+ * MIPS-specific semaphore code.
+ *
+ * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
+ * Copyright (C) 2004 Ralf Baechle <ralf@linux-mips.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * April 2001 - Reworked by Paul Mackerras <paulus@samba.org>
+ * to eliminate the SMP races in the old version between the updates
+ * of `count' and `waking'. Now we use negative `count' values to
+ * indicate that some process(es) are waiting for the semaphore.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <asm/cpu-features.h>
+#include <asm/errno.h>
+#include <asm/semaphore.h>
+#include <asm/war.h>
+/*
+ * 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;
+ *
+ * On machines without lld/scd we need a spinlock to make the manipulation of
+ * sem->count and sem->waking atomic. Scalability isn't an issue because
+ * this lock is used on UP only so it's just an empty variable.
+ */
+static inline int __sem_update_count(struct semaphore *sem, int incr)
+{
+ int old_count, tmp;
+
+ if (cpu_has_llsc && R10000_LLSC_WAR) {
+ __asm__ __volatile__(
+ "1: ll %0, %2 \n"
+ " sra %1, %0, 31 \n"
+ " not %1 \n"
+ " and %1, %0, %1 \n"
+ " add %1, %1, %3 \n"
+ " sc %1, %2 \n"
+ " beqzl %1, 1b \n"
+ : "=&r" (old_count), "=&r" (tmp), "=m" (sem->count)
+ : "r" (incr), "m" (sem->count));
+ } else if (cpu_has_llsc) {
+ __asm__ __volatile__(
+ "1: ll %0, %2 \n"
+ " sra %1, %0, 31 \n"
+ " not %1 \n"
+ " and %1, %0, %1 \n"
+ " add %1, %1, %3 \n"
+ " sc %1, %2 \n"
+ " beqz %1, 1b \n"
+ : "=&r" (old_count), "=&r" (tmp), "=m" (sem->count)
+ : "r" (incr), "m" (sem->count));
+ } else {
+ static DEFINE_SPINLOCK(semaphore_lock);
+ unsigned long flags;
+
+ spin_lock_irqsave(&semaphore_lock, flags);
+ old_count = atomic_read(&sem->count);
+ tmp = max_t(int, old_count, 0) + incr;
+ atomic_set(&sem->count, tmp);
+ spin_unlock_irqrestore(&semaphore_lock, flags);
+ }
+
+ return old_count;
+}
+
+void __up(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);
+}
+
+EXPORT_SYMBOL(__up);
+
+/*
+ * Note that when we come in to __down or __down_interruptible,
+ * we have already decremented count, but that decrement was
+ * ineffective since the result was < 0, and any negative value
+ * of count is equivalent to 0.
+ * Thus it is only when we decrement count from some value > 0
+ * that we have actually got the semaphore.
+ */
+void __sched __down(struct semaphore *sem)
+{
+ struct task_struct *tsk = current;
+ DECLARE_WAITQUEUE(wait, tsk);
+
+ __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ 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);
+ __set_task_state(tsk, 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);
+}
+
+EXPORT_SYMBOL(__down);
+
+int __sched __down_interruptible(struct semaphore * sem)
+{
+ int retval = 0;
+ struct task_struct *tsk = current;
+ DECLARE_WAITQUEUE(wait, tsk);
+
+ __set_task_state(tsk, TASK_INTERRUPTIBLE);
+ 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);
+ retval = -EINTR;
+ break;
+ }
+ schedule();
+ set_task_state(tsk, TASK_INTERRUPTIBLE);
+ }
+ remove_wait_queue(&sem->wait, &wait);
+ __set_task_state(tsk, TASK_RUNNING);
+
+ wake_up(&sem->wait);
+ return retval;
+}
+
+EXPORT_SYMBOL(__down_interruptible);