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/*
* Mach Operating System
* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University.
* Copyright (c) 1993,1994 The University of Utah and
* the Computer Systems Laboratory (CSL).
* 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, THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF
* THIS SOFTWARE IN ITS "AS IS" CONDITION, AND DISCLAIM 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.
*/
/*
* File: eventcount.c
* Author: Alessandro Forin
* Date: 10/91
*
* Eventcounters, for user-level drivers synchronization
*
*/
#include <kern/printf.h>
#include <string.h>
#include <mach/machine.h>
#include <kern/ast.h>
#include <kern/debug.h>
#include "cpu_number.h"
#include <kern/lock.h>
#include <kern/processor.h>
#include <kern/queue.h>
#include <kern/sched.h>
#include <kern/sched_prim.h>
#include <kern/thread.h>
#include <machine/machspl.h> /* For def'n of splsched() */
#include <kern/eventcount.h>
#define MAX_EVCS 10 /* xxx for now */
evc_t all_eventcounters[MAX_EVCS];
/*
* Initialization
*/
void
evc_init(evc_t ev)
{
int i;
memset(ev, 0, sizeof(*ev));
/* keep track of who is who */
for (i = 0; i < MAX_EVCS; i++)
if (all_eventcounters[i] == 0) break;
if (i == MAX_EVCS) {
printf("Too many eventcounters\n");
return;
}
all_eventcounters[i] = ev;
ev->ev_id = i;
ev->sanity = ev;
ev->waiting_thread = THREAD_NULL;
simple_lock_init(&ev->lock);
}
/*
* Finalization
*/
void
evc_destroy(evc_t ev)
{
evc_signal(ev);
ev->sanity = 0;
if (all_eventcounters[ev->ev_id] == ev)
all_eventcounters[ev->ev_id] = 0;
ev->ev_id = -1;
}
/*
* Thread termination.
* HORRIBLE. This stuff needs to be fixed.
*/
void evc_notify_abort(const thread_t thread)
{
int i;
evc_t ev;
int s = splsched();
for (i = 0; i < MAX_EVCS; i++) {
ev = all_eventcounters[i];
if (ev) {
simple_lock(&ev->lock);
if (ev->waiting_thread == thread)
{
ev->waiting_thread = 0;
/* Removal of a waiting thread has to bump the count by one */
ev->count++;
}
simple_unlock(&ev->lock);
}
}
splx(s);
}
/*
* Just so that we return success, and give
* up the stack while blocked
*/
static void __attribute__((noreturn))
evc_continue(void)
{
thread_syscall_return(KERN_SUCCESS);
/* NOTREACHED */
}
/*
* User-trappable
*/
kern_return_t evc_wait(natural_t ev_id)
{
spl_t s;
kern_return_t ret;
evc_t ev;
if ((ev_id >= MAX_EVCS) ||
((ev = all_eventcounters[ev_id]) == 0) ||
(ev->ev_id != ev_id) || (ev->sanity != ev))
return KERN_INVALID_ARGUMENT;
s = splsched();
simple_lock(&ev->lock);
/*
* The values assumed by the "count" field are
* as follows:
* 0 At initialization time, and with no
* waiting thread means no events pending;
* with waiting thread means the event
* was signalled and the thread not yet resumed
* -1 no events, there must be a waiting thread
* N>0 no waiting thread means N pending,
* with waiting thread N-1 pending.
*
*/
if (ev->count > 0) {
ev->count--;
ret = KERN_SUCCESS;
} else {
if (ev->waiting_thread == THREAD_NULL) {
ev->count--;
ev->waiting_thread = current_thread();
assert_wait((event_t) 0, TRUE); /* ifnot race */
simple_unlock(&ev->lock);
thread_block(evc_continue);
return KERN_SUCCESS;
}
ret = KERN_NO_SPACE; /* XX */
}
simple_unlock(&ev->lock);
splx(s);
return ret;
}
/*
* User-trappable
*/
kern_return_t evc_wait_clear(natural_t ev_id)
{
spl_t s;
evc_t ev;
if ((ev_id >= MAX_EVCS) ||
((ev = all_eventcounters[ev_id]) == 0) ||
(ev->ev_id != ev_id) || (ev->sanity != ev))
return KERN_INVALID_ARGUMENT;
s = splsched();
simple_lock(&ev->lock);
/*
* The values assumed by the "count" field are
* as follows:
* 0 At initialization time, and with no
* waiting thread means no events pending;
* with waiting thread means the event
* was signalled and the thread not yet resumed
* -1 no events, there must be a waiting thread
* N>0 no waiting thread means N pending,
* with waiting thread N-1 pending.
*
*/
/*
* Note that we always clear count before blocking.
*/
if (ev->waiting_thread == THREAD_NULL) {
ev->count = -1;
ev->waiting_thread = current_thread();
assert_wait((event_t) 0, TRUE); /* ifnot race */
simple_unlock(&ev->lock);
thread_block(evc_continue);
/* NOTREACHED */
}
simple_unlock(&ev->lock);
splx(s);
return KERN_NO_SPACE; /* XX */
}
/*
* Called exclusively from interrupt context
*/
void
evc_signal(evc_t ev)
{
volatile thread_t thread;
int state;
spl_t s;
if (ev->sanity != ev)
return;
s = splsched();
simple_lock(&ev->lock);
ev->count++;
if (thread = ev->waiting_thread, thread != THREAD_NULL)
{
ev->waiting_thread = 0;
#if (NCPUS > 1)
retry:
while((thread->state & TH_RUN) || thread->lock.lock_data)
;
#endif
thread_lock(thread);
/* make thread runnable on this processor */
/* taken from clear_wait */
switch ((state = thread->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_unlock(thread);
#if NCPUS > 1
thread_setrun(thread, TRUE);
#else
simpler_thread_setrun(thread, TRUE);
#endif
break;
case TH_RUN | TH_WAIT:
#if (NCPUS > 1)
/*
* Legal on MP: between assert_wait()
* and thread_block(), in evc_wait() above.
*
* Mmm. Maybe don't need now that the while(..) check is
* done before the thread lock is grabbed.....
*/
thread_unlock(thread);
goto retry;
#else
/*FALLTHROUGH*/
#endif
case TH_WAIT | TH_SUSP:
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.
* Just clear the wait.
*/
thread->state = state &~ TH_WAIT;
thread_unlock(thread);
break;
default:
/*
* Not waiting.
*/
panic("evc_signal.3");
thread_unlock(thread);
break;
}
}
simple_unlock(&ev->lock);
splx(s);
}
#if NCPUS <= 1
/*
* The scheduler is too messy for my old little brain
*/
void
simpler_thread_setrun(
thread_t th,
boolean_t may_preempt)
{
struct run_queue *rq;
int whichq;
/*
* XXX should replace queue with a boolean in this case.
*/
if (default_pset.idle_count > 0) {
processor_t processor;
processor = (processor_t) queue_first(&default_pset.idle_queue);
queue_remove(&default_pset.idle_queue, processor,
processor_t, processor_queue);
default_pset.idle_count--;
processor->next_thread = th;
processor->state = PROCESSOR_DISPATCHING;
return;
}
rq = &(master_processor->runq);
ast_on(cpu_number(), AST_BLOCK);
whichq = (th)->sched_pri;
simple_lock(&(rq)->lock); /* lock the run queue */
enqueue_head(&(rq)->runq[whichq], &((th)->links));
if (whichq < (rq)->low || (rq)->count == 0)
(rq)->low = whichq; /* minimize */
(rq)->count++;
#ifdef MIGRATING_THREADS
(th)->shuttle.runq = (rq);
#else
(th)->runq = (rq);
#endif
simple_unlock(&(rq)->lock);
/*
* Turn off first_quantum to allow context switch.
*/
current_processor()->first_quantum = FALSE;
}
#endif /* NCPUS > 1 */
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