minix/kernel/system/do_exit.c

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/* The system call implemented in this file:
* m_type: SYS_EXIT
*
* The parameters for this system call are:
* m1_i1: PR_PROC_NR (slot number of exiting process)
*/
#include "../system.h"
#if USE_EXIT
FORWARD _PROTOTYPE( void clear_proc, (register struct proc *rc));
/*===========================================================================*
* do_exit *
*===========================================================================*/
PUBLIC int do_exit(m_ptr)
message *m_ptr; /* pointer to request message */
{
/* Handle sys_exit. A user process has exited or a system process requests
* to exit. Only the PM can request other process slots to be cleared.
* The routine to clean up a process table slot cancels outstanding timers,
* possibly removes the process from the message queues, and resets certain
* process table fields to the default values.
*/
int exit_proc_nr;
/* Determine what process exited. User processes are handled here. */
if (PM_PROC_NR == m_ptr->m_source) {
exit_proc_nr = m_ptr->PR_PROC_NR; /* get exiting process */
if (exit_proc_nr != SELF) { /* PM tries to exit self */
if (! isokprocn(exit_proc_nr)) return(EINVAL);
clear_proc(proc_addr(exit_proc_nr)); /* exit a user process */
return(OK); /* report back to PM */
}
}
/* The PM or some other system process requested to be exited. */
clear_proc(proc_addr(m_ptr->m_source));
return(EDONTREPLY);
}
/*===========================================================================*
* clear_proc *
*===========================================================================*/
PRIVATE void clear_proc(rc)
register struct proc *rc; /* slot of process to clean up */
{
register struct proc *rp; /* iterate over process table */
register struct proc **xpp; /* iterate over caller queue */
int i;
/* Turn off any alarm timers at the clock. */
reset_timer(&priv(rc)->s_alarm_timer);
/* Make sure that the exiting process is no longer scheduled. */
if (rc->p_rts_flags == 0) lock_unready(rc);
/* If the process being terminated happens to be queued trying to send a
* message (e.g., the process was killed by a signal, rather than it doing
* a normal exit), then it must be removed from the message queues.
*/
if (rc->p_rts_flags & SENDING) {
/* Check all proc slots to see if the exiting process is queued. */
for (rp = BEG_PROC_ADDR; rp < END_PROC_ADDR; rp++) {
if (rp->p_caller_q == NIL_PROC) continue;
/* Make sure that the exiting process is not on the queue. */
xpp = &rp->p_caller_q;
while (*xpp != NIL_PROC) { /* check entire queue */
if (*xpp == rc) { /* process is on the queue */
*xpp = (*xpp)->p_q_link; /* replace by next process */
break;
}
xpp = &(*xpp)->p_q_link; /* proceed to next queued */
}
}
}
/* Check the table with IRQ hooks to see if hooks should be released. */
for (i=0; i < NR_IRQ_HOOKS; i++) {
if (irq_hooks[i].proc_nr == proc_nr(rc)) {
rm_irq_handler(&irq_hooks[i]); /* remove interrupt handler */
irq_hooks[i].proc_nr = NONE; /* mark hook as free */
}
}
/* Now it is safe to release the process table slot. If this is a system
* process, also release its privilege structure. Further cleanup is not
* needed at this point. All important fields are reinitialized when the
* slots are assigned to another, new process.
*/
rc->p_rts_flags = SLOT_FREE;
if (priv(rc)->s_flags & SYS_PROC) priv(rc)->s_proc_nr = NONE;
}
#endif /* USE_EXIT */