Author: kib
Date: Wed Aug 15 15:56:21 2012
New Revision: 239301
URL: http://svn.freebsd.org/changeset/base/239301
Log:
Add a sysctl kern.pid_max, which limits the maximum pid the system is
allowed to allocate, and corresponding tunable with the same
name. Note that existing processes with higher pids are left intact.
MFC after: 1 week
Modified:
head/sys/kern/init_main.c
head/sys/kern/kern_fork.c
head/sys/kern/kern_mib.c
head/sys/kern/kern_thread.c
head/sys/kern/subr_param.c
head/sys/nlm/nlm_advlock.c
head/sys/sys/proc.h
Modified: head/sys/kern/init_main.c
==============================================================================
--- head/sys/kern/init_main.c Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/kern/init_main.c Wed Aug 15 15:56:21 2012 (r239301)
@@ -476,6 +476,7 @@ proc0_init(void *dummy __unused)
knlist_init_mtx(&p->p_klist, &p->p_mtx);
STAILQ_INIT(&p->p_ktr);
p->p_nice = NZERO;
+ /* pid_max cannot be greater then PID_MAX */
td->td_tid = PID_MAX + 1;
LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
td->td_state = TDS_RUNNING;
Modified: head/sys/kern/kern_fork.c
==============================================================================
--- head/sys/kern/kern_fork.c Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/kern/kern_fork.c Wed Aug 15 15:56:21 2012 (r239301)
@@ -209,8 +209,8 @@ sysctl_kern_randompid(SYSCTL_HANDLER_ARG
pid = randompid;
error = sysctl_handle_int(oidp, &pid, 0, req);
if (error == 0 && req->newptr != NULL) {
- if (pid < 0 || pid > PID_MAX - 100) /* out of range */
- pid = PID_MAX - 100;
+ if (pid < 0 || pid > pid_max - 100) /* out of range */
+ pid = pid_max - 100;
else if (pid < 2) /* NOP */
pid = 0;
else if (pid < 100) /* Make it reasonable */
@@ -259,8 +259,8 @@ retry:
* restart somewhat above 0, as the low-numbered procs
* tend to include daemons that don't exit.
*/
- if (trypid >= PID_MAX) {
- trypid = trypid % PID_MAX;
+ if (trypid >= pid_max) {
+ trypid = trypid % pid_max;
if (trypid < 100)
trypid += 100;
pidchecked = 0;
Modified: head/sys/kern/kern_mib.c
==============================================================================
--- head/sys/kern/kern_mib.c Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/kern/kern_mib.c Wed Aug 15 15:56:21 2012 (r239301)
@@ -499,6 +499,30 @@ SYSCTL_INT(_debug_sizeof, OID_AUTO, vnod
SYSCTL_INT(_debug_sizeof, OID_AUTO, proc, CTLFLAG_RD,
0, sizeof(struct proc), "sizeof(struct proc)");
+static int
+sysctl_kern_pid_max(SYSCTL_HANDLER_ARGS)
+{
+ int error, pm;
+
+ pm = pid_max;
+ error = sysctl_handle_int(oidp, &pm, 0, req);
+ if (error || !req->newptr)
+ return (error);
+ sx_xlock(&proctree_lock);
+ sx_xlock(&allproc_lock);
+ /* Only permit the values less then PID_MAX. */
+ if (pm > PID_MAX)
+ error = EINVAL;
+ else
+ pid_max = pm;
+ sx_xunlock(&allproc_lock);
+ sx_xunlock(&proctree_lock);
+ return (error);
+}
+SYSCTL_PROC(_kern, OID_AUTO, pid_max, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_TUN |
+ CTLFLAG_MPSAFE, 0, 0, sysctl_kern_pid_max, "I",
+ "Maximum allowed pid");
+
#include <sys/bio.h>
#include <sys/buf.h>
SYSCTL_INT(_debug_sizeof, OID_AUTO, bio, CTLFLAG_RD,
Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/kern/kern_thread.c Wed Aug 15 15:56:21 2012 (r239301)
@@ -269,7 +269,11 @@ threadinit(void)
{
mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
- /* leave one number for thread0 */
+
+ /*
+ * pid_max cannot be greater then PID_MAX.
+ * leave one number for thread0.
+ */
tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
Modified: head/sys/kern/subr_param.c
==============================================================================
--- head/sys/kern/subr_param.c Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/kern/subr_param.c Wed Aug 15 15:56:21 2012 (r239301)
@@ -41,12 +41,13 @@ __FBSDID("$FreeBSD$");
#include "opt_msgbuf.h"
#include "opt_maxusers.h"
-#include <sys/limits.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
-#include <sys/sysctl.h>
+#include <sys/limits.h>
#include <sys/msgbuf.h>
+#include <sys/sysctl.h>
+#include <sys/proc.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
@@ -92,6 +93,7 @@ int ncallout; /* maximum # of timer ev
int nbuf;
int ngroups_max; /* max # groups per process */
int nswbuf;
+pid_t pid_max = PID_MAX;
long maxswzone; /* max swmeta KVA storage */
long maxbcache; /* max buffer cache KVA storage */
long maxpipekva; /* Limit on pipe KVA */
@@ -250,6 +252,13 @@ init_param1(void)
TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
if (ngroups_max < NGROUPS_MAX)
ngroups_max = NGROUPS_MAX;
+
+ /*
+ * Only allow to lower the maximal pid.
+ */
+ TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
+ if (pid_max > PID_MAX)
+ pid_max = PID_MAX;
}
/*
Modified: head/sys/nlm/nlm_advlock.c
==============================================================================
--- head/sys/nlm/nlm_advlock.c Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/nlm/nlm_advlock.c Wed Aug 15 15:56:21 2012 (r239301)
@@ -98,6 +98,7 @@ nlm_client_init(void *dummy)
int i;
mtx_init(&nlm_svid_lock, "NLM svid lock", NULL, MTX_DEF);
+ /* pid_max cannot be greater then PID_MAX */
nlm_svid_allocator = new_unrhdr(PID_MAX + 2, INT_MAX, &nlm_svid_lock);
for (i = 0; i < NLM_SVID_HASH_SIZE; i++)
LIST_INIT(&nlm_file_svids[i]);
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Wed Aug 15 15:53:27 2012 (r239300)
+++ head/sys/sys/proc.h Wed Aug 15 15:56:21 2012 (r239301)
@@ -696,11 +696,12 @@ MALLOC_DECLARE(M_SUBPROC);
#define FIRST_THREAD_IN_PROC(p) TAILQ_FIRST(&(p)->p_threads)
/*
- * We use process IDs <= PID_MAX; PID_MAX + 1 must also fit in a pid_t,
- * as it is used to represent "no process group".
+ * We use process IDs <= pid_max <= PID_MAX; PID_MAX + 1 must also fit
+ * in a pid_t, as it is used to represent "no process group".
*/
#define PID_MAX 99999
#define NO_PID 100000
+extern pid_t pid_max;
#define SESS_LEADER(p) ((p)->p_session->s_leader == (p))
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