Move pid allocation to the bottom of the process allocation, so that we
don't have to deal with partially initialized proc structs in the scheduler. Pointed out by: Artur Grabowski and Chuck Silvers.
This commit is contained in:
christos
parent
7e96d57199
commit
0ecf004286
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_fork.c,v 1.94 2002/09/25 22:21:42 thorpej Exp $ */
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/* $NetBSD: kern_fork.c,v 1.95 2002/10/21 17:37:53 christos Exp $ */
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/*-
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* Copyright (c) 1999, 2001 The NetBSD Foundation, Inc.
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@ -78,7 +78,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.94 2002/09/25 22:21:42 thorpej Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.95 2002/10/21 17:37:53 christos Exp $");
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#include "opt_ktrace.h"
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#include "opt_systrace.h"
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@ -249,85 +249,6 @@ fork1(struct proc *p1, int flags, int exitsig, void *stack, size_t stacksize,
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/* Allocate new proc. */
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p2 = pool_get(&proc_pool, PR_WAITOK);
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/*
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* BEGIN PID ALLOCATION.
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*/
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s = proclist_lock_write();
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/*
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* Find an unused process ID. We remember a range of unused IDs
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* ready to use (from nextpid+1 through pidchecked-1).
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*/
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nextpid++;
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retry:
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/*
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* If the process ID prototype has wrapped around,
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* restart somewhat above 0, as the low-numbered procs
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* tend to include daemons that don't exit.
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*/
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if (nextpid >= PID_MAX) {
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nextpid = 500;
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pidchecked = 0;
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}
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if (nextpid >= pidchecked) {
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const struct proclist_desc *pd;
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pidchecked = PID_MAX;
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/*
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* Scan the process lists to check whether this pid
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* is in use. Remember the lowest pid that's greater
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* than nextpid, so we can avoid checking for a while.
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*/
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pd = proclists;
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again:
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LIST_FOREACH(tp, pd->pd_list, p_list) {
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while (tp->p_pid == nextpid ||
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tp->p_pgrp->pg_id == nextpid ||
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tp->p_session->s_sid == nextpid) {
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nextpid++;
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if (nextpid >= pidchecked)
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goto retry;
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}
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if (tp->p_pid > nextpid && pidchecked > tp->p_pid)
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pidchecked = tp->p_pid;
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if (tp->p_pgrp->pg_id > nextpid &&
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pidchecked > tp->p_pgrp->pg_id)
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pidchecked = tp->p_pgrp->pg_id;
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if (tp->p_session->s_sid > nextpid &&
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pidchecked > tp->p_session->s_sid)
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pidchecked = tp->p_session->s_sid;
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}
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/*
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* If there's another list, scan it. If we have checked
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* them all, we've found one!
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*/
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pd++;
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if (pd->pd_list != NULL)
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goto again;
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}
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/*
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* Put the proc on allproc before unlocking PID allocation
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* so that waiters won't grab it as soon as we unlock.
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*/
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p2->p_stat = SIDL; /* protect against others */
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p2->p_pid = nextpid;
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p2->p_exitsig = exitsig; /* signal for parent on exit */
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p2->p_forw = p2->p_back = NULL; /* shouldn't be necessary */
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LIST_INSERT_HEAD(&allproc, p2, p_list);
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LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
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/*
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* END PID ALLOCATION.
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*/
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proclist_unlock_write(s);
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/*
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* Make a proc table entry for the new process.
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* Start by zeroing the section of proc that is zero-initialized,
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@ -470,6 +391,85 @@ fork1(struct proc *p1, int flags, int exitsig, void *stack, size_t stacksize,
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(func != NULL) ? func : child_return,
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(arg != NULL) ? arg : p2);
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/*
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* BEGIN PID ALLOCATION.
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*/
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s = proclist_lock_write();
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/*
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* Find an unused process ID. We remember a range of unused IDs
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* ready to use (from nextpid+1 through pidchecked-1).
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*/
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nextpid++;
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retry:
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/*
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* If the process ID prototype has wrapped around,
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* restart somewhat above 0, as the low-numbered procs
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* tend to include daemons that don't exit.
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*/
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if (nextpid >= PID_MAX) {
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nextpid = 500;
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pidchecked = 0;
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}
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if (nextpid >= pidchecked) {
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const struct proclist_desc *pd;
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pidchecked = PID_MAX;
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/*
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* Scan the process lists to check whether this pid
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* is in use. Remember the lowest pid that's greater
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* than nextpid, so we can avoid checking for a while.
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*/
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pd = proclists;
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again:
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LIST_FOREACH(tp, pd->pd_list, p_list) {
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while (tp->p_pid == nextpid ||
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tp->p_pgrp->pg_id == nextpid ||
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tp->p_session->s_sid == nextpid) {
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nextpid++;
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if (nextpid >= pidchecked)
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goto retry;
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}
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if (tp->p_pid > nextpid && pidchecked > tp->p_pid)
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pidchecked = tp->p_pid;
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if (tp->p_pgrp->pg_id > nextpid &&
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pidchecked > tp->p_pgrp->pg_id)
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pidchecked = tp->p_pgrp->pg_id;
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if (tp->p_session->s_sid > nextpid &&
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pidchecked > tp->p_session->s_sid)
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pidchecked = tp->p_session->s_sid;
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}
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/*
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* If there's another list, scan it. If we have checked
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* them all, we've found one!
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*/
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pd++;
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if (pd->pd_list != NULL)
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goto again;
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}
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/*
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* Put the proc on allproc before unlocking PID allocation
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* so that waiters won't grab it as soon as we unlock.
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*/
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p2->p_stat = SIDL; /* protect against others */
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p2->p_pid = nextpid;
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p2->p_exitsig = exitsig; /* signal for parent on exit */
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p2->p_forw = p2->p_back = NULL; /* shouldn't be necessary */
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LIST_INSERT_HEAD(&allproc, p2, p_list);
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LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
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/*
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* END PID ALLOCATION.
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*/
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proclist_unlock_write(s);
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/*
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* Make child runnable, set start time, and add to run queue.
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*/
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