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, 164 insertions, 0 deletions

diff --git a/arch/mips/kernel/semaphore.c b/arch/mips/kernel/semaphore.c
new file mode 100644
index 000000000000..9c40fe5a8e8d
--- /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);