Initial Spring 2016 commit.

kern/include/synch.h

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
+ *	The President and Fellows of Harvard College.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _SYNCH_H_
+#define _SYNCH_H_
+
+/*
+ * Header file for synchronization primitives.
+ */
+
+
+#include <spinlock.h>
+
+/*
+ * Dijkstra-style semaphore.
+ *
+ * The name field is for easier debugging. A copy of the name is made
+ * internally.
+ */
+struct semaphore {
+        char *sem_name;
+	struct wchan *sem_wchan;
+	struct spinlock sem_lock;
+        volatile unsigned sem_count;
+};
+
+struct semaphore *sem_create(const char *name, unsigned initial_count);
+void sem_destroy(struct semaphore *);
+
+/*
+ * Operations (both atomic):
+ *     P (proberen): decrement count. If the count is 0, block until
+ *                   the count is 1 again before decrementing.
+ *     V (verhogen): increment count.
+ */
+void P(struct semaphore *);
+void V(struct semaphore *);
+
+
+/*
+ * Simple lock for mutual exclusion.
+ *
+ * When the lock is created, no thread should be holding it. Likewise,
+ * when the lock is destroyed, no thread should be holding it.
+ *
+ * The name field is for easier debugging. A copy of the name is
+ * (should be) made internally.
+ */
+struct lock {
+        char *lk_name;
+        // add what you need here
+        // (don't forget to mark things volatile as needed)
+};
+
+struct lock *lock_create(const char *name);
+void lock_destroy(struct lock *);
+
+/*
+ * Operations:
+ *    lock_acquire - Get the lock. Only one thread can hold the lock at the
+ *                   same time.
+ *    lock_release - Free the lock. Only the thread holding the lock may do
+ *                   this.
+ *    lock_do_i_hold - Return true if the current thread holds the lock;
+ *                   false otherwise.
+ *
+ * These operations must be atomic. You get to write them.
+ */
+void lock_acquire(struct lock *);
+void lock_release(struct lock *);
+bool lock_do_i_hold(struct lock *);
+
+
+/*
+ * Condition variable.
+ *
+ * Note that the "variable" is a bit of a misnomer: a CV is normally used
+ * to wait until a variable meets a particular condition, but there's no
+ * actual variable, as such, in the CV.
+ *
+ * These CVs are expected to support Mesa semantics, that is, no
+ * guarantees are made about scheduling.
+ *
+ * The name field is for easier debugging. A copy of the name is
+ * (should be) made internally.
+ */
+
+struct cv {
+        char *cv_name;
+        // add what you need here
+        // (don't forget to mark things volatile as needed)
+};
+
+struct cv *cv_create(const char *name);
+void cv_destroy(struct cv *);
+
+/*
+ * Operations:
+ *    cv_wait      - Release the supplied lock, go to sleep, and, after
+ *                   waking up again, re-acquire the lock.
+ *    cv_signal    - Wake up one thread that's sleeping on this CV.
+ *    cv_broadcast - Wake up all threads sleeping on this CV.
+ *
+ * For all three operations, the current thread must hold the lock passed
+ * in. Note that under normal circumstances the same lock should be used
+ * on all operations with any particular CV.
+ *
+ * These operations must be atomic. You get to write them.
+ */
+void cv_wait(struct cv *cv, struct lock *lock);
+void cv_signal(struct cv *cv, struct lock *lock);
+void cv_broadcast(struct cv *cv, struct lock *lock);
+
+
+#endif /* _SYNCH_H_ */