Initial source

1 files changed, 287 insertions, 0 deletions

diff --git a/kern/ipc_sched.c b/kern/ipc_sched.c
new file mode 100644
index 0000000..a2f4c35
--- /dev/null
+++ b/kern/ipc_sched.c
@@ -0,0 +1,287 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1993, 1992,1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+
+#include <cpus.h>
+#include <mach_host.h>
+
+#include <mach/message.h>
+#include <kern/counters.h>
+#include "cpu_number.h"
+#include <kern/lock.h>
+#include <kern/thread.h>
+#include <kern/sched_prim.h>
+#include <kern/processor.h>
+#include <kern/time_out.h>
+#include <kern/thread_swap.h>
+#include <kern/ipc_sched.h>
+#include <machine/machspl.h>	/* for splsched/splx */
+#include <machine/pmap.h>
+
+
+
+/*
+ *	These functions really belong in kern/sched_prim.c.
+ */
+
+/*
+ *	Routine:	thread_go
+ *	Purpose:
+ *		Start a thread running.
+ *	Conditions:
+ *		IPC locks may be held.
+ */
+
+void
+thread_go(
+	thread_t thread)
+{
+	int	state;
+	spl_t	s;
+
+	s = splsched();
+	thread_lock(thread);
+
+	reset_timeout_check(&thread->timer);
+
+	state = thread->state;
+	switch (state & TH_SCHED_STATE) {
+
+	    case TH_WAIT | TH_SUSP | TH_UNINT:
+	    case TH_WAIT	   | TH_UNINT:
+	    case TH_WAIT:
+		/*
+		 *	Sleeping and not suspendable - put
+		 *	on run queue.
+		 */
+		thread->state = (state &~ TH_WAIT) | TH_RUN;
+		thread->wait_result = THREAD_AWAKENED;
+		thread_setrun(thread, TRUE);
+		break;
+
+	    case	  TH_WAIT | TH_SUSP:
+	    case TH_RUN | TH_WAIT:
+	    case TH_RUN | TH_WAIT | TH_SUSP:
+	    case TH_RUN | TH_WAIT	    | TH_UNINT:
+	    case TH_RUN | TH_WAIT | TH_SUSP | TH_UNINT:
+		/*
+		 *	Either already running, or suspended.
+		 */
+		thread->state = state & ~TH_WAIT;
+		thread->wait_result = THREAD_AWAKENED;
+		break;
+
+	    default:
+		/*
+		 *	Not waiting.
+		 */
+		break;
+	}
+
+	thread_unlock(thread);
+	splx(s);
+}
+
+/*
+ *	Routine:	thread_will_wait
+ *	Purpose:
+ *		Assert that the thread intends to block.
+ */
+
+void
+thread_will_wait(
+	thread_t thread)
+{
+	spl_t	s;
+
+	s = splsched();
+	thread_lock(thread);
+
+	assert(thread->wait_result = -1);	/* for later assertions */
+	thread->state |= TH_WAIT;
+
+	thread_unlock(thread);
+	splx(s);
+}
+
+/*
+ *	Routine:	thread_will_wait_with_timeout
+ *	Purpose:
+ *		Assert that the thread intends to block,
+ *		with a timeout.
+ */
+
+void
+thread_will_wait_with_timeout(
+	thread_t thread,
+	mach_msg_timeout_t msecs)
+{
+	natural_t ticks = convert_ipc_timeout_to_ticks(msecs);
+	spl_t	s;
+
+	s = splsched();
+	thread_lock(thread);
+
+	assert(thread->wait_result = -1);	/* for later assertions */
+	thread->state |= TH_WAIT;
+
+	set_timeout(&thread->timer, ticks);
+
+	thread_unlock(thread);
+	splx(s);
+}
+
+#if	MACH_HOST
+#define check_processor_set(thread)	\
+	    (current_processor()->processor_set == (thread)->processor_set)
+#else	/* MACH_HOST */
+#define	check_processor_set(thread)	TRUE
+#endif	/* MACH_HOST */
+
+#if	NCPUS > 1
+#define	check_bound_processor(thread) \
+	    ((thread)->bound_processor == PROCESSOR_NULL || \
+	     (thread)->bound_processor == current_processor())
+#else	/* NCPUS > 1 */
+#define	check_bound_processor(thread)	TRUE
+#endif	/* NCPUS > 1 */
+
+#ifdef CONTINUATIONS
+/*
+ *	Routine:	thread_handoff
+ *	Purpose:
+ *		Switch to a new thread (new), leaving the current
+ *		thread (old) blocked.  If successful, moves the
+ *		kernel stack from old to new and returns as the
+ *		new thread.  An explicit continuation for the old thread
+ *		must be supplied.
+ *
+ *		NOTE:  Although we wakeup new, we don't set new->wait_result.
+ *	Returns:
+ *		TRUE if the handoff happened.
+ */
+
+boolean_t
+thread_handoff(
+	register thread_t old,
+	register continuation_t continuation,
+	register thread_t new)
+{
+	spl_t	s;
+
+	assert(current_thread() == old);
+
+	/*
+	 *	XXX Dubious things here:
+	 *	I don't check the idle_count on the processor set.
+	 *	No scheduling priority or policy checks.
+	 *	I assume the new thread is interruptible.
+	 */
+
+	s = splsched();
+	thread_lock(new);
+
+	/*
+	 *	The first thing we must do is check the state
+	 *	of the threads, to ensure we can handoff.
+	 *	This check uses current_processor()->processor_set,
+	 *	which we can read without locking.
+	 */
+
+	if ((old->stack_privilege == current_stack()) ||
+	    (new->state != (TH_WAIT|TH_SWAPPED)) ||
+	     !check_processor_set(new) ||
+	     !check_bound_processor(new)) {
+		thread_unlock(new);
+		(void) splx(s);
+
+		counter_always(c_thread_handoff_misses++);
+		return FALSE;
+	}
+
+	reset_timeout_check(&new->timer);
+
+	new->state = TH_RUN;
+	thread_unlock(new);
+
+#if	NCPUS > 1
+	new->last_processor = current_processor();
+#endif	/* NCPUS > 1 */
+
+	ast_context(new, cpu_number());
+	timer_switch(&new->system_timer);
+
+	/*
+	 *	stack_handoff is machine-dependent.  It does the
+	 *	machine-dependent components of a context-switch, like
+	 *	changing address spaces.  It updates active_threads.
+	 */
+
+	stack_handoff(old, new);
+
+	/*
+	 *	Now we must dispose of the old thread.
+	 *	This is like thread_continue, except
+	 *	that the old thread isn't waiting yet.
+	 */
+
+	thread_lock(old);
+	old->swap_func = continuation;
+	assert(old->wait_result = -1);		/* for later assertions */
+
+	if (old->state == TH_RUN) {
+		/*
+		 *	This is our fast path.
+		 */
+
+		old->state = TH_WAIT|TH_SWAPPED;
+	}
+	else if (old->state == (TH_RUN|TH_SUSP)) {
+		/*
+		 *	Somebody is trying to suspend the thread.
+		 */
+
+		old->state = TH_WAIT|TH_SUSP|TH_SWAPPED;
+		if (old->wake_active) {
+			/*
+			 *	Someone wants to know when the thread
+			 *	really stops.
+			 */
+			old->wake_active = FALSE;
+			thread_unlock(old);
+			thread_wakeup((event_t)&old->wake_active);
+			goto after_old_thread;
+		}
+	} else
+		panic("thread_handoff");
+
+	thread_unlock(old);
+    after_old_thread:
+	(void) splx(s);
+
+	counter_always(c_thread_handoff_hits++);
+	return TRUE;
+}
+#endif /* CONTINUATIONS */