void P(struct semaphore* sig){
if (!sig->INT)
cli();
sig->value--;
if (sig->value < 0){
queue_delete(current_pcb);
if (sig->value == -1){
current_pcb->pre_pcb = current_pcb;
current_pcb->next_pcb = current_pcb;
sig->waitlist = current_pcb;
}
else
queue_insert(sig->waitlist, current_pcb); /*wait*/
proc_run--;
if (sig->INT)
pick_proc();
else
yield();
}
if (!sig->INT)
sti();
}
/*===========================================================================*
* switch_to_user *
*===========================================================================*/
PUBLIC void switch_to_user(void)
{
/* This function is called an instant before proc_ptr is
* to be scheduled again.
*/
/*
* if the current process is still runnable check the misc flags and let
* it run unless it becomes not runnable in the meantime
*/
if (proc_is_runnable(proc_ptr))
goto check_misc_flags;
/*
* if a process becomes not runnable while handling the misc flags, we
* need to pick a new one here and start from scratch. Also if the
* current process wasn' runnable, we pick a new one here
*/
not_runnable_pick_new:
if (proc_is_preempted(proc_ptr)) {
proc_ptr->p_rts_flags &= ~RTS_PREEMPTED;
if (proc_is_runnable(proc_ptr)) {
if (!is_zero64(proc_ptr->p_cpu_time_left))
enqueue_head(proc_ptr);
else
enqueue(proc_ptr);
}
}
/*
* if we have no process to run, set IDLE as the current process for
* time accounting and put the cpu in and idle state. After the next
* timer interrupt the execution resumes here and we can pick another
* process. If there is still nothing runnable we "schedule" IDLE again
*/
while (!(proc_ptr = pick_proc())) {
proc_ptr = proc_addr(IDLE);
if (priv(proc_ptr)->s_flags & BILLABLE)
bill_ptr = proc_ptr;
idle();
}
switch_address_space(proc_ptr);
check_misc_flags:
assert(proc_ptr);
assert(proc_is_runnable(proc_ptr));
while (proc_ptr->p_misc_flags &
(MF_KCALL_RESUME | MF_DELIVERMSG |
MF_SC_DEFER | MF_SC_TRACE | MF_SC_ACTIVE)) {
assert(proc_is_runnable(proc_ptr));
if (proc_ptr->p_misc_flags & MF_KCALL_RESUME) {
kernel_call_resume(proc_ptr);
}
else if (proc_ptr->p_misc_flags & MF_DELIVERMSG) {
TRACE(VF_SCHEDULING, printf("delivering to %s / %d\n",
proc_ptr->p_name, proc_ptr->p_endpoint););
delivermsg(proc_ptr);
}
/*===========================================================================*
* schedcheck *
*===========================================================================*/
PUBLIC struct proc * schedcheck(void)
{
/* This function is called an instant before proc_ptr is
* to be scheduled again.
*/
NOREC_ENTER(schedch);
vmassert(intr_disabled());
/*
* if the current process is still runnable check the misc flags and let
* it run unless it becomes not runnable in the meantime
*/
if (proc_is_runnable(proc_ptr))
goto check_misc_flags;
/*
* if a process becomes not runnable while handling the misc flags, we
* need to pick a new one here and start from scratch. Also if the
* current process wasn' runnable, we pick a new one here
*/
not_runnable_pick_new:
if (proc_is_preempted(proc_ptr)) {
proc_ptr->p_rts_flags &= ~RTS_PREEMPTED;
if (proc_is_runnable(proc_ptr))
enqueue_head(proc_ptr);
}
/* this enqueues the process again */
if (proc_no_quantum(proc_ptr))
RTS_UNSET(proc_ptr, RTS_NO_QUANTUM);
/*
* if we have no process to run, set IDLE as the current process for
* time accounting and put the cpu in and idle state. After the next
* timer interrupt the execution resumes here and we can pick another
* process. If there is still nothing runnable we "schedule" IDLE again
*/
while( !(proc_ptr = pick_proc())) {
proc_ptr = proc_addr(IDLE);
if (priv(proc_ptr)->s_flags & BILLABLE)
bill_ptr = proc_ptr;
idle();
}
check_misc_flags:
vmassert(proc_ptr);
vmassert(proc_is_runnable(proc_ptr));
while (proc_ptr->p_misc_flags &
(MF_DELIVERMSG | MF_SC_DEFER | MF_SC_TRACE | MF_SC_ACTIVE)) {
vmassert(proc_is_runnable(proc_ptr));
if (proc_ptr->p_misc_flags & MF_DELIVERMSG) {
TRACE(VF_SCHEDULING, printf("delivering to %s / %d\n",
proc_ptr->p_name, proc_ptr->p_endpoint););
if(delivermsg(proc_ptr) == VMSUSPEND) {
TRACE(VF_SCHEDULING,
printf("suspending %s / %d\n",
proc_ptr->p_name,
proc_ptr->p_endpoint););
