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minix/servers/pm/forkexit.c
Tomas Hruby b09bcf6779 Scheduling server (by Bjorn Swift) 
In this second phase, scheduling is moved from PM to its own
scheduler (see r6557 for phase one). In the next phase we hope to a)
include useful information in the "out of quantum" message and b)
create some simple scheduling policy that makes use of that
information.

When the system starts up, PM will iterate over its process table and
ask SCHED to take over scheduling unprivileged processes. This is
done by sending a SCHEDULING_START message to SCHED. This message
includes the processes endpoint, the parent's endpoint and its nice
level. The scheduler adds this process to its schedproc table, issues
a schedctl, and returns its own endpoint to PM - as the endpoint of
the effective scheduler. When a process terminates, a SCHEDULING_STOP
message is sent to the scheduler.

The reason for this effective endpoint is for future compatibility.
Some day, we may have a scheduler that, instead of scheduling the
process itself, forwards the SCHEDULING_START message on to another
scheduler.

PM has information on who schedules whom. As such, scheduling
messages from user-land are sent through PM. An example is when
processes change their priority, using nice(). In that case, a
getsetpriority message is sent to PM, which then sends a
SCHEDULING_SET_NICE to the process's effective scheduler.

When a process is forked through PM, it inherits its parent's
scheduler, but is spawned with an empty quantum. As before, a request
to fork a process flows through VM before returning to PM, which then
wakes up the child process. This flow has been modified slightly so
that PM notifies the scheduler of the new process, before waking up
the child process. If the scheduler fails to take over scheduling,
the child process is torn down and the fork fails with an erroneous
value.

Process priority is entirely decided upon using nice levels. PM
stores a copy of each process's nice level and when a child is
forked, its parent's nice level is sent in the SCHEDULING_START
message. How this level is mapped to a priority queue is up to the
scheduler. It should be noted that the nice level is used to
determine the max_priority and the parent could have been in a lower
priority when it was spawned. To prevent a CPU intensive process from
hawking the CPU by continuously forking children that get scheduled
in the max_priority, the scheduler should determine in which queue
the parent is currently scheduled, and schedule the child in that
same queue.

Other fixes: The USER_Q in kernel/proc.h was incorrectly defined as
NR_SCHED_QUEUES/2. That results in a "off by one" error when
converting priority->nice->priority for nice=0. This also had the
side effect that if someone were to set the MAX_USER_Q to something
else than 0, then USER_Q would be off.
2010-05-18 13:39:04 +00:00

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/* This file deals with creating processes (via FORK) and deleting them (via
* EXIT/WAIT). When a process forks, a new slot in the 'mproc' table is
* allocated for it, and a copy of the parent's core image is made for the
* child. Then the kernel and file system are informed. A process is removed
* from the 'mproc' table when two events have occurred: (1) it has exited or
* been killed by a signal, and (2) the parent has done a WAIT. If the process
* exits first, it continues to occupy a slot until the parent does a WAIT.
*
* The entry points into this file are:
* do_fork: perform the FORK system call
* do_srv_fork: special FORK, used by RS to create sys services
* do_exit: perform the EXIT system call (by calling exit_proc())
* exit_proc: actually do the exiting, and tell FS about it
* exit_restart: continue exiting a process after FS has replied
* do_waitpid: perform the WAITPID or WAIT system call
* wait_test: check whether a parent is waiting for a child
*/
#include "pm.h"
#include <sys/wait.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/vm.h>
#include <sys/ptrace.h>
#include <sys/resource.h>
#include <signal.h>
#include "mproc.h"
#include "param.h"
#define LAST_FEW 2 /* last few slots reserved for superuser */
FORWARD _PROTOTYPE (void zombify, (struct mproc *rmp) );
FORWARD _PROTOTYPE (void check_parent, (struct mproc *child,
int try_cleanup) );
FORWARD _PROTOTYPE (void tell_parent, (struct mproc *child) );
FORWARD _PROTOTYPE (void tell_tracer, (struct mproc *child) );
FORWARD _PROTOTYPE (void tracer_died, (struct mproc *child) );
FORWARD _PROTOTYPE (void cleanup, (register struct mproc *rmp) );
/*===========================================================================*
* do_fork *
*===========================================================================*/
PUBLIC int do_fork()
{
/* The process pointed to by 'mp' has forked. Create a child process. */
register struct mproc *rmp; /* pointer to parent */
register struct mproc *rmc; /* pointer to child */
pid_t new_pid;
static int next_child;
int i, n = 0, s;
endpoint_t child_ep;
message m;
/* If tables might fill up during FORK, don't even start since recovery half
* way through is such a nuisance.
*/
rmp = mp;
if ((procs_in_use == NR_PROCS) ||
(procs_in_use >= NR_PROCS-LAST_FEW && rmp->mp_effuid != 0))
{
printf("PM: warning, process table is full!\n");
return(EAGAIN);
}
/* Find a slot in 'mproc' for the child process. A slot must exist. */
do {
next_child = (next_child+1) % NR_PROCS;
n++;
} while((mproc[next_child].mp_flags & IN_USE) && n <= NR_PROCS);
if(n > NR_PROCS)
panic("do_fork can't find child slot");
if(next_child < 0 || next_child >= NR_PROCS
|| (mproc[next_child].mp_flags & IN_USE))
panic("do_fork finds wrong child slot: %d", next_child);
/* Memory part of the forking. */
if((s=vm_fork(rmp->mp_endpoint, next_child, &child_ep)) != OK) {
printf("PM: vm_fork failed: %d\n", s);
return s;
}
/* PM may not fail fork after call to vm_fork(), as VM calls sys_fork(). */
rmc = &mproc[next_child];
/* Set up the child and its memory map; copy its 'mproc' slot from parent. */
procs_in_use++;
*rmc = *rmp; /* copy parent's process slot to child's */
rmc->mp_parent = who_p; /* record child's parent */
if (!(rmc->mp_trace_flags & TO_TRACEFORK)) {
rmc->mp_tracer = NO_TRACER; /* no tracer attached */
rmc->mp_trace_flags = 0;
sigemptyset(&rmc->mp_sigtrace);
}
/* Inherit only these flags. In normal fork(), PRIV_PROC is not inherited. */
rmc->mp_flags &= (IN_USE|DELAY_CALL);
rmc->mp_child_utime = 0; /* reset administration */
rmc->mp_child_stime = 0; /* reset administration */
rmc->mp_exitstatus = 0;
rmc->mp_sigstatus = 0;
rmc->mp_endpoint = child_ep; /* passed back by VM */
for (i = 0; i < NR_ITIMERS; i++)
rmc->mp_interval[i] = 0; /* reset timer intervals */
/* Find a free pid for the child and put it in the table. */
new_pid = get_free_pid();
rmc->mp_pid = new_pid; /* assign pid to child */
m.m_type = PM_FORK;
m.PM_PROC = rmc->mp_endpoint;
m.PM_PPROC = rmp->mp_endpoint;
m.PM_CPID = rmc->mp_pid;
tell_fs(rmc, &m);
/* Tell the tracer, if any, about the new child */
if (rmc->mp_tracer != NO_TRACER)
sig_proc(rmc, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */);
/* Do not reply until FS is ready to process the fork
* request
*/
return SUSPEND;
}
/*===========================================================================*
* do_srv_fork *
*===========================================================================*/
PUBLIC int do_srv_fork()
{
/* The process pointed to by 'mp' has forked. Create a child process. */
register struct mproc *rmp; /* pointer to parent */
register struct mproc *rmc; /* pointer to child */
int s;
pid_t new_pid;
static int next_child;
int i, n = 0;
endpoint_t child_ep;
message m;
/* Only RS is allowed to use srv_fork. */
if (mp->mp_endpoint != RS_PROC_NR)
return EPERM;
/* If tables might fill up during FORK, don't even start since recovery half
* way through is such a nuisance.
*/
rmp = mp;
if ((procs_in_use == NR_PROCS) ||
(procs_in_use >= NR_PROCS-LAST_FEW && rmp->mp_effuid != 0))
{
printf("PM: warning, process table is full!\n");
return(EAGAIN);
}
/* Find a slot in 'mproc' for the child process. A slot must exist. */
do {
next_child = (next_child+1) % NR_PROCS;
n++;
} while((mproc[next_child].mp_flags & IN_USE) && n <= NR_PROCS);
if(n > NR_PROCS)
panic("do_fork can't find child slot");
if(next_child < 0 || next_child >= NR_PROCS
|| (mproc[next_child].mp_flags & IN_USE))
panic("do_fork finds wrong child slot: %d", next_child);
if((s=vm_fork(rmp->mp_endpoint, next_child, &child_ep)) != OK) {
printf("PM: vm_fork failed: %d\n", s);
return s;
}
rmc = &mproc[next_child];
/* Set up the child and its memory map; copy its 'mproc' slot from parent. */
procs_in_use++;
*rmc = *rmp; /* copy parent's process slot to child's */
rmc->mp_parent = who_p; /* record child's parent */
if (!(rmc->mp_trace_flags & TO_TRACEFORK)) {
rmc->mp_tracer = NO_TRACER; /* no tracer attached */
rmc->mp_trace_flags = 0;
sigemptyset(&rmc->mp_sigtrace);
}
/* inherit only these flags */
rmc->mp_flags &= (IN_USE|PRIV_PROC|DELAY_CALL);
rmc->mp_child_utime = 0; /* reset administration */
rmc->mp_child_stime = 0; /* reset administration */
rmc->mp_exitstatus = 0;
rmc->mp_sigstatus = 0;
rmc->mp_endpoint = child_ep; /* passed back by VM */
for (i = 0; i < NR_ITIMERS; i++)
rmc->mp_interval[i] = 0; /* reset timer intervals */
/* Find a free pid for the child and put it in the table. */
new_pid = get_free_pid();
rmc->mp_pid = new_pid; /* assign pid to child */
m.m_type = PM_SRV_FORK;
m.PM_PROC = rmc->mp_endpoint;
m.PM_PPROC = rmp->mp_endpoint;
m.PM_CPID = rmc->mp_pid;
tell_fs(rmc, &m);
/* Tell the tracer, if any, about the new child */
if (rmc->mp_tracer != NO_TRACER)
sig_proc(rmc, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */);
/* Wakeup the newly created process */
setreply(rmc-mproc, OK);
return rmc->mp_pid;
}
/*===========================================================================*
* do_exit *
*===========================================================================*/
PUBLIC int do_exit()
{
/* Perform the exit(status) system call. The real work is done by exit_proc(),
* which is also called when a process is killed by a signal. System processes
* do not use PM's exit() to terminate. If they try to, we warn the user
* and send a SIGKILL signal to the system process.
*/
if(mp->mp_flags & PRIV_PROC) {
printf("PM: system process %d (%s) tries to exit(), sending SIGKILL\n",
mp->mp_endpoint, mp->mp_name);
sys_kill(mp->mp_endpoint, SIGKILL);
}
else {
exit_proc(mp, m_in.status, FALSE /*dump_core*/);
}
return(SUSPEND); /* can't communicate from beyond the grave */
}
/*===========================================================================*
* exit_proc *
*===========================================================================*/
PUBLIC void exit_proc(rmp, exit_status, dump_core)
register struct mproc *rmp; /* pointer to the process to be terminated */
int exit_status; /* the process' exit status (for parent) */
int dump_core; /* flag indicating whether to dump core */
{
/* A process is done. Release most of the process' possessions. If its
* parent is waiting, release the rest, else keep the process slot and
* become a zombie.
*/
register int proc_nr, proc_nr_e;
int r;
pid_t procgrp;
struct mproc *p_mp;
clock_t user_time, sys_time;
message m;
/* Do not create core files for set uid execution */
if (dump_core && rmp->mp_realuid != rmp->mp_effuid)
dump_core = FALSE;
/* System processes are destroyed before informing FS, meaning that FS can
* not get their CPU state, so we can't generate a coredump for them either.
*/
if (dump_core && (rmp->mp_flags & PRIV_PROC))
dump_core = FALSE;
proc_nr = (int) (rmp - mproc); /* get process slot number */
proc_nr_e = rmp->mp_endpoint;
/* Remember a session leader's process group. */
procgrp = (rmp->mp_pid == mp->mp_procgrp) ? mp->mp_procgrp : 0;
/* If the exited process has a timer pending, kill it. */
if (rmp->mp_flags & ALARM_ON) set_alarm(rmp, (clock_t) 0);
/* Do accounting: fetch usage times and accumulate at parent. */
if((r=sys_times(proc_nr_e, &user_time, &sys_time, NULL, NULL)) != OK)
panic("exit_proc: sys_times failed: %d", r);
p_mp = &mproc[rmp->mp_parent]; /* process' parent */
p_mp->mp_child_utime += user_time + rmp->mp_child_utime; /* add user time */
p_mp->mp_child_stime += sys_time + rmp->mp_child_stime; /* add system time */
/* Tell the kernel the process is no longer runnable to prevent it from
* being scheduled in between the following steps. Then tell FS that it
* the process has exited and finally, clean up the process at the kernel.
* This order is important so that FS can tell drivers to cancel requests
* such as copying to/ from the exiting process, before it is gone.
*/
if ((r = sys_stop(proc_nr_e)) != OK) /* stop the process */
panic("sys_stop failed: %d", r);
if((r=vm_willexit(proc_nr_e)) != OK) {
panic("exit_proc: vm_willexit failed: %d", r);
}
vm_notify_sig_wrapper(rmp->mp_endpoint);
if (proc_nr_e == INIT_PROC_NR)
{
printf("PM: INIT died\n");
return;
}
if (proc_nr_e == FS_PROC_NR)
{
panic("exit_proc: FS died: %d", r);
}
/* Tell FS about the exiting process. */
m.m_type = dump_core ? PM_DUMPCORE : PM_EXIT;
m.PM_PROC = rmp->mp_endpoint;
tell_fs(rmp, &m);
if (rmp->mp_flags & PRIV_PROC)
{
/* Destroy system processes without waiting for FS. This is
* needed because the system process might be a block device
* driver that FS is blocked waiting on.
*/
if((r= sys_clear(rmp->mp_endpoint)) != OK)
panic("exit_proc: sys_clear failed: %d", r);
}
/* Clean up most of the flags describing the process's state before the exit,
* and mark it as exiting.
*/
rmp->mp_flags &= (IN_USE|FS_CALL|PRIV_PROC|TRACE_EXIT);
rmp->mp_flags |= EXITING;
/* Keep the process around until FS is finished with it. */
rmp->mp_exitstatus = (char) exit_status;
/* For normal exits, try to notify the parent as soon as possible.
* For core dumps, notify the parent only once the core dump has been made.
*/
if (!dump_core)
zombify(rmp);
/* If the process has children, disinherit them. INIT is the new parent. */
for (rmp = &mproc[0]; rmp < &mproc[NR_PROCS]; rmp++) {
if (!(rmp->mp_flags & IN_USE)) continue;
if (rmp->mp_tracer == proc_nr) {
/* This child's tracer died. Do something sensible. */
tracer_died(rmp);
}
if (rmp->mp_parent == proc_nr) {
/* 'rmp' now points to a child to be disinherited. */
rmp->mp_parent = INIT_PROC_NR;
/* Notify new parent. */
if (rmp->mp_flags & ZOMBIE)
check_parent(rmp, TRUE /*try_cleanup*/);
}
}
/* Send a hangup to the process' process group if it was a session leader. */
if (procgrp != 0) check_sig(-procgrp, SIGHUP, FALSE /* ksig */);
}
/*===========================================================================*
* exit_restart *
*===========================================================================*/
PUBLIC void exit_restart(rmp, dump_core)
struct mproc *rmp; /* pointer to the process being terminated */
int dump_core; /* flag indicating whether to dump core */
{
/* FS replied to our exit or coredump request. Perform the second half of the
* exit code.
*/
int r;
/* For core dumps, now is the right time to try to contact the parent. */
if (dump_core)
zombify(rmp);
if (!(rmp->mp_flags & PRIV_PROC))
{
/* destroy the (user) process */
if((r=sys_clear(rmp->mp_endpoint)) != OK)
panic("exit_restart: sys_clear failed: %d", r);
}
/* Release the memory occupied by the child. */
if((r=vm_exit(rmp->mp_endpoint)) != OK) {
panic("exit_restart: vm_exit failed: %d", r);
}
if (rmp->mp_flags & TRACE_EXIT)
{
/* Wake up the tracer, completing the ptrace(T_EXIT) call */
mproc[rmp->mp_tracer].mp_reply.reply_trace = 0;
setreply(rmp->mp_tracer, OK);
}
/* Clean up if the parent has collected the exit status */
if (rmp->mp_flags & TOLD_PARENT)
cleanup(rmp);
}
/*===========================================================================*
* do_waitpid *
*===========================================================================*/
PUBLIC int do_waitpid()
{
/* A process wants to wait for a child to terminate. If a child is already
* waiting, go clean it up and let this WAIT call terminate. Otherwise,
* really wait.
* A process calling WAIT never gets a reply in the usual way at the end
* of the main loop (unless WNOHANG is set or no qualifying child exists).
* If a child has already exited, the routine tell_parent() sends the reply
* to awaken the caller.
* Both WAIT and WAITPID are handled by this code.
*/
register struct mproc *rp;
int i, pidarg, options, children;
/* Set internal variables, depending on whether this is WAIT or WAITPID. */
pidarg = (call_nr == WAIT ? -1 : m_in.pid); /* 1st param of waitpid */
options = (call_nr == WAIT ? 0 : m_in.sig_nr); /* 3rd param of waitpid */
if (pidarg == 0) pidarg = -mp->mp_procgrp; /* pidarg < 0 ==> proc grp */
/* Is there a child waiting to be collected? At this point, pidarg != 0:
* pidarg > 0 means pidarg is pid of a specific process to wait for
* pidarg == -1 means wait for any child
* pidarg < -1 means wait for any child whose process group = -pidarg
*/
children = 0;
for (rp = &mproc[0]; rp < &mproc[NR_PROCS]; rp++) {
if ((rp->mp_flags & (IN_USE | TOLD_PARENT)) != IN_USE) continue;
if (rp->mp_parent != who_p && rp->mp_tracer != who_p) continue;
if (rp->mp_parent != who_p && (rp->mp_flags & ZOMBIE)) continue;
/* The value of pidarg determines which children qualify. */
if (pidarg > 0 && pidarg != rp->mp_pid) continue;
if (pidarg < -1 && -pidarg != rp->mp_procgrp) continue;
children++; /* this child is acceptable */
if (rp->mp_tracer == who_p) {
if (rp->mp_flags & TRACE_ZOMBIE) {
/* Traced child meets the pid test and has exited. */
tell_tracer(rp);
check_parent(rp, TRUE /*try_cleanup*/);
return(SUSPEND);
}
if (rp->mp_flags & STOPPED) {
/* This child meets the pid test and is being traced.
* Deliver a signal to the tracer, if any.
*/
for (i = 1; i < _NSIG; i++) {
if (sigismember(&rp->mp_sigtrace, i)) {
sigdelset(&rp->mp_sigtrace, i);
mp->mp_reply.reply_res2 =
0177 | (i << 8);
return(rp->mp_pid);
}
}
}
}
if (rp->mp_parent == who_p) {
if (rp->mp_flags & ZOMBIE) {
/* This child meets the pid test and has exited. */
tell_parent(rp); /* this child has already exited */
if (!(rp->mp_flags & FS_CALL))
cleanup(rp);
return(SUSPEND);
}
}
}
/* No qualifying child has exited. Wait for one, unless none exists. */
if (children > 0) {
/* At least 1 child meets the pid test exists, but has not exited. */
if (options & WNOHANG) {
return(0); /* parent does not want to wait */
}
mp->mp_flags |= WAITING; /* parent wants to wait */
mp->mp_wpid = (pid_t) pidarg; /* save pid for later */
return(SUSPEND); /* do not reply, let it wait */
} else {
/* No child even meets the pid test. Return error immediately. */
return(ECHILD); /* no - parent has no children */
}
}
/*===========================================================================*
* wait_test *
*===========================================================================*/
PUBLIC int wait_test(rmp, child)
struct mproc *rmp; /* process that may be waiting */
struct mproc *child; /* process that may be waited for */
{
/* See if a parent or tracer process is waiting for a child process.
* A tracer is considered to be a pseudo-parent.
*/
int parent_waiting, right_child;
pid_t pidarg;
pidarg = rmp->mp_wpid; /* who's being waited for? */
parent_waiting = rmp->mp_flags & WAITING;
right_child = /* child meets one of the 3 tests? */
(pidarg == -1 || pidarg == child->mp_pid ||
-pidarg == child->mp_procgrp);
return (parent_waiting && right_child);
}
/*===========================================================================*
* zombify *
*===========================================================================*/
PRIVATE void zombify(rmp)
struct mproc *rmp;
{
/* Zombify a process. First check if the exiting process is traced by a process
* other than its parent; if so, the tracer must be notified about the exit
* first. Once that is done, the real parent may be notified about the exit of
* its child.
*/
struct mproc *t_mp;
if (rmp->mp_flags & (TRACE_ZOMBIE | ZOMBIE))
panic("zombify: process was already a zombie");
/* See if we have to notify a tracer process first. */
if (rmp->mp_tracer != NO_TRACER && rmp->mp_tracer != rmp->mp_parent) {
rmp->mp_flags |= TRACE_ZOMBIE;
t_mp = &mproc[rmp->mp_tracer];
/* Do not bother sending SIGCHLD signals to tracers. */
if (!wait_test(t_mp, rmp))
return;
tell_tracer(rmp);
}
else {
rmp->mp_flags |= ZOMBIE;
}
/* No tracer, or tracer is parent, or tracer has now been notified. */
check_parent(rmp, FALSE /*try_cleanup*/);
}
/*===========================================================================*
* check_parent *
*===========================================================================*/
PRIVATE void check_parent(child, try_cleanup)
struct mproc *child; /* tells which process is exiting */
int try_cleanup; /* clean up the child when done? */
{
/* We would like to inform the parent of an exiting child about the child's
* death. If the parent is waiting for the child, tell it immediately;
* otherwise, send it a SIGCHLD signal.
*
* Note that we may call this function twice on a single child; first with
* its original parent, later (if the parent died) with INIT as its parent.
*/
struct mproc *p_mp;
p_mp = &mproc[child->mp_parent];
if (p_mp->mp_flags & EXITING) {
/* This may trigger if the child of a dead parent dies. The child will
* be assigned to INIT and rechecked shortly after. Do nothing.
*/
}
else if (wait_test(p_mp, child)) {
tell_parent(child);
/* The 'try_cleanup' flag merely saves us from having to be really
* careful with statement ordering in exit_proc() and exit_restart().
*/
if (try_cleanup && !(child->mp_flags & FS_CALL))
cleanup(child);
}
else {
/* Parent is not waiting. */
sig_proc(p_mp, SIGCHLD, TRUE /*trace*/, FALSE /* ksig */);
}
}
/*===========================================================================*
* tell_parent *
*===========================================================================*/
PRIVATE void tell_parent(child)
register struct mproc *child; /* tells which process is exiting */
{
int exitstatus, mp_parent;
struct mproc *parent;
mp_parent= child->mp_parent;
if (mp_parent <= 0)
panic("tell_parent: bad value in mp_parent: %d", mp_parent);
if(!(child->mp_flags & ZOMBIE))
panic("tell_parent: child not a zombie");
if(child->mp_flags & TOLD_PARENT)
panic("tell_parent: telling parent again");
parent = &mproc[mp_parent];
/* Wake up the parent by sending the reply message. */
exitstatus = (child->mp_exitstatus << 8) | (child->mp_sigstatus & 0377);
parent->mp_reply.reply_res2 = exitstatus;
setreply(child->mp_parent, child->mp_pid);
parent->mp_flags &= ~WAITING; /* parent no longer waiting */
child->mp_flags &= ~ZOMBIE; /* child no longer a zombie */
child->mp_flags |= TOLD_PARENT; /* avoid informing parent twice */
}
/*===========================================================================*
* tell_tracer *
*===========================================================================*/
PRIVATE void tell_tracer(child)
struct mproc *child; /* tells which process is exiting */
{
int exitstatus, mp_tracer;
struct mproc *tracer;
mp_tracer = child->mp_tracer;
if (mp_tracer <= 0)
panic("tell_tracer: bad value in mp_tracer: %d", mp_tracer);
if(!(child->mp_flags & TRACE_ZOMBIE))
panic("tell_tracer: child not a zombie");
tracer = &mproc[mp_tracer];
exitstatus = (child->mp_exitstatus << 8) | (child->mp_sigstatus & 0377);
tracer->mp_reply.reply_res2 = exitstatus;
setreply(child->mp_tracer, child->mp_pid);
tracer->mp_flags &= ~WAITING; /* tracer no longer waiting */
child->mp_flags &= ~TRACE_ZOMBIE; /* child no longer zombie to tracer */
child->mp_flags |= ZOMBIE; /* child is now zombie to parent */
}
/*===========================================================================*
* tracer_died *
*===========================================================================*/
PRIVATE void tracer_died(child)
struct mproc *child; /* process being traced */
{
/* The process that was tracing the given child, has died for some reason.
* This is really the tracer's fault, but we can't let INIT deal with this.
*/
child->mp_tracer = NO_TRACER;
child->mp_flags &= ~TRACE_EXIT;
/* If the tracer died while the child was running or stopped, we have no
* idea what state the child is in. Avoid a trainwreck, by killing the child.
* Note that this may cause cascading exits.
*/
if (!(child->mp_flags & EXITING)) {
sig_proc(child, SIGKILL, TRUE /*trace*/, FALSE /* ksig */);
return;
}
/* If the tracer died while the child was telling it about its own death,
* forget about the tracer and notify the real parent instead.
*/
if (child->mp_flags & TRACE_ZOMBIE) {
child->mp_flags &= ~TRACE_ZOMBIE;
child->mp_flags |= ZOMBIE;
check_parent(child, TRUE /*try_cleanup*/);
}
}
/*===========================================================================*
* cleanup *
*===========================================================================*/
PRIVATE void cleanup(rmp)
register struct mproc *rmp; /* tells which process is exiting */
{
/* Release the process table entry and reinitialize some field. */
rmp->mp_pid = 0;
rmp->mp_flags = 0;
rmp->mp_child_utime = 0;
rmp->mp_child_stime = 0;
procs_in_use--;
}
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