/*
* Copyright (C) 2006 Ondrej Palkovsky
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <libadt/list.h>
#include <psthread.h>
#include <malloc.h>
#include <unistd.h>
#include <thread.h>
#include <stdio.h>
#include <kernel/arch/faddr.h>
#include <futex.h>
#include <assert.h>
#ifndef PSTHREAD_INITIAL_STACK_PAGES_NO
#define PSTHREAD_INITIAL_STACK_PAGES_NO 1
#endif
static LIST_INITIALIZE(ready_list);
static LIST_INITIALIZE(manager_list);
static void psthread_exit(void) __attribute__ ((noinline));
static void psthread_main(void);
static atomic_t psthread_futex = FUTEX_INITIALIZER;
/** Setup PSthread information into TCB structure */
psthread_data_t * psthread_setup()
{
psthread_data_t *pt;
tcb_t *tcb;
tcb = __make_tls();
if (!tcb)
return NULL;
if (!pt) {
__free_tls(tcb);
return NULL;
}
tcb->pst_data = pt;
pt->tcb = tcb;
return pt;
}
void psthread_teardown(psthread_data_t *pt)
{
__free_tls(pt->tcb);
}
/** Function to preempt to other pseudo thread without adding
* currently running pseudo thread to ready_list.
*/
void psthread_exit(void)
{
psthread_data_t *pt;
futex_down(&psthread_futex);
if (!list_empty(&ready_list))
pt = list_get_instance(ready_list.next, psthread_data_t, link);
else if (!list_empty(&manager_list))
pt = list_get_instance(manager_list.next, psthread_data_t, link);
else {
printf("Cannot find suitable psthread to run.\n"); _exit(0);
}
list_remove(&pt->link);
futex_up(&psthread_futex);
context_restore(&pt->ctx);
/* Never reached */
}
/** Function that is called on entry to new uspace thread */
void psthread_main(void)
{
psthread_data_t *pt = __tcb_get()->pst_data;
pt->retval = pt->func(pt->arg);
pt->finished = 1;
if (pt->waiter)
list_append(&pt->waiter->link, &ready_list);
psthread_exit();
}
/** Schedule next userspace pseudo thread.
*
* @param tomanager If true, we are switching to next ready manager thread
* (if none is found, thread is exited)
* @param frommanager If true, we are switching from manager thread
* @return 0 if there is no ready pseudo thread, 1 otherwise.
*/
int psthread_schedule_next_adv(pschange_type ctype)
{
psthread_data_t *pt;
int retval = 0;
futex_down(&psthread_futex);
if (ctype == PS_PREEMPT && list_empty(&ready_list))
goto ret_0;
if (ctype == PS_FROM_MANAGER && list_empty(&ready_list)) {
goto ret_0;
}
assert(!(ctype
== PS_TO_MANAGER
&& list_empty
(&manager_list
)));
pt = __tcb_get()->pst_data;
if (!context_save(&pt->ctx))
return 1; // futex_up already done here
if (ctype == PS_PREEMPT)
list_append(&pt->link, &ready_list);
else if (ctype == PS_FROM_MANAGER)
list_append(&pt->link, &manager_list);
if (ctype == PS_TO_MANAGER)
pt = list_get_instance(manager_list.next,psthread_data_t, link);
else
pt = list_get_instance(ready_list.next, psthread_data_t, link);
list_remove(&pt->link);
futex_up(&psthread_futex);
context_restore(&pt->ctx);
ret_0:
futex_up(&psthread_futex);
return retval;
}
/** Wait for uspace pseudo thread to finish.
*
* @param psthrid Pseudo thread to wait for.
*
* @return Value returned by the finished thread.
*/
int psthread_join(pstid_t psthrid)
{
volatile psthread_data_t *pt, *mypt;
volatile int retval;
/* Handle psthrid = Kernel address -> it is wait for call */
pt = (psthread_data_t *) psthrid;
if (!pt->finished) {
mypt = __tcb_get()->pst_data;
if (context_save(&((psthread_data_t *) mypt)->ctx)) {
pt->waiter = (psthread_data_t *) mypt;
psthread_exit();
}
}
retval = pt->retval;
psthread_teardown((void *)pt);
return retval;
}
/**
* Create a userspace thread
*
* @param func Pseudo thread function.
* @param arg Argument to pass to func.
*
* @return 0 on failure, TLS of the new pseudo thread.
*/
pstid_t psthread_create(int (*func)(void *), void *arg)
{
psthread_data_t *pt;
pt = psthread_setup();
if (!pt)
return 0;
pt
->stack
= (char *) malloc(PSTHREAD_INITIAL_STACK_PAGES_NO
*getpagesize
());
if (!pt->stack) {
psthread_teardown(pt);
return 0;
}
pt->arg= arg;
pt->func = func;
pt->finished = 0;
pt->waiter = NULL;
context_save(&pt->ctx);
context_set(&pt->ctx, FADDR(psthread_main), pt->stack, PSTHREAD_INITIAL_STACK_PAGES_NO*getpagesize(),
pt->tcb);
return (pstid_t )pt;
}
/** Add a thread to ready list */
void psthread_add_ready(pstid_t psthrid)
{
psthread_data_t *pt;
pt = (psthread_data_t *) psthrid;
futex_down(&psthread_futex);
list_append(&pt->link, &ready_list);
futex_up(&psthread_futex);
}
/** Add a thread to manager list */
void psthread_add_manager(pstid_t psthrid)
{
psthread_data_t *pt;
pt = (psthread_data_t *) psthrid;
futex_down(&psthread_futex);
list_append(&pt->link, &manager_list);
futex_up(&psthread_futex);
}
/** Remove one manager from manager list */
void psthread_remove_manager()
{
futex_down(&psthread_futex);
if (list_empty(&manager_list)) {
printf("No manager found!.\n"); futex_up(&psthread_futex);
return;
}
list_remove(manager_list.next);
futex_up(&psthread_futex);
}