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freebsd-skq/sys/kern/kern_resource.c
Tim J. Robbins 5ce623b8e0 Add an XXX comment noting that getrusage() accesses p_stats->p_ru 
and p_stats->p_cru without holding the appropriate locks.
2003-02-13 09:53:59 +00:00

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/*-
* Copyright (c) 1982, 1986, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_resource.c 8.5 (Berkeley) 1/21/94
* $FreeBSD$
*/
#include "opt_compat.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/file.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/sysent.h>
#include <sys/time.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
static int donice(struct thread *td, struct proc *chgp, int n);
static MALLOC_DEFINE(M_UIDINFO, "uidinfo", "uidinfo structures");
#define UIHASH(uid) (&uihashtbl[(uid) & uihash])
static struct mtx uihashtbl_mtx;
static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash; /* size of hash table - 1 */
static struct uidinfo *uilookup(uid_t uid);
/*
* Resource controls and accounting.
*/
#ifndef _SYS_SYSPROTO_H_
struct getpriority_args {
int which;
int who;
};
#endif
/*
* MPSAFE
*/
int
getpriority(td, uap)
struct thread *td;
register struct getpriority_args *uap;
{
struct proc *p;
int low = PRIO_MAX + 1;
int error = 0;
struct ksegrp *kg;
mtx_lock(&Giant);
switch (uap->which) {
case PRIO_PROCESS:
if (uap->who == 0)
low = td->td_ksegrp->kg_nice;
else {
p = pfind(uap->who);
if (p == NULL)
break;
if (p_cansee(td, p) == 0) {
FOREACH_KSEGRP_IN_PROC(p, kg) {
if (kg->kg_nice < low)
low = kg->kg_nice;
}
}
PROC_UNLOCK(p);
}
break;
case PRIO_PGRP: {
register struct pgrp *pg;
sx_slock(&proctree_lock);
if (uap->who == 0) {
pg = td->td_proc->p_pgrp;
PGRP_LOCK(pg);
} else {
pg = pgfind(uap->who);
if (pg == NULL) {
sx_sunlock(&proctree_lock);
break;
}
}
sx_sunlock(&proctree_lock);
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
PROC_LOCK(p);
if (!p_cansee(td, p)) {
FOREACH_KSEGRP_IN_PROC(p, kg) {
if (kg->kg_nice < low)
low = kg->kg_nice;
}
}
PROC_UNLOCK(p);
}
PGRP_UNLOCK(pg);
break;
}
case PRIO_USER:
if (uap->who == 0)
uap->who = td->td_ucred->cr_uid;
sx_slock(&allproc_lock);
LIST_FOREACH(p, &allproc, p_list) {
PROC_LOCK(p);
if (!p_cansee(td, p) &&
p->p_ucred->cr_uid == uap->who) {
FOREACH_KSEGRP_IN_PROC(p, kg) {
if (kg->kg_nice < low)
low = kg->kg_nice;
}
}
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
break;
default:
error = EINVAL;
break;
}
if (low == PRIO_MAX + 1 && error == 0)
error = ESRCH;
td->td_retval[0] = low;
mtx_unlock(&Giant);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct setpriority_args {
int which;
int who;
int prio;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
setpriority(td, uap)
struct thread *td;
register struct setpriority_args *uap;
{
struct proc *curp = td->td_proc;
register struct proc *p;
int found = 0, error = 0;
mtx_lock(&Giant);
switch (uap->which) {
case PRIO_PROCESS:
if (uap->who == 0) {
PROC_LOCK(curp);
error = donice(td, curp, uap->prio);
PROC_UNLOCK(curp);
} else {
p = pfind(uap->who);
if (p == 0)
break;
if (p_cansee(td, p) == 0)
error = donice(td, p, uap->prio);
PROC_UNLOCK(p);
}
found++;
break;
case PRIO_PGRP: {
register struct pgrp *pg;
sx_slock(&proctree_lock);
if (uap->who == 0) {
pg = curp->p_pgrp;
PGRP_LOCK(pg);
} else {
pg = pgfind(uap->who);
if (pg == NULL) {
sx_sunlock(&proctree_lock);
break;
}
}
sx_sunlock(&proctree_lock);
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
PROC_LOCK(p);
if (!p_cansee(td, p)) {
error = donice(td, p, uap->prio);
found++;
}
PROC_UNLOCK(p);
}
PGRP_UNLOCK(pg);
break;
}
case PRIO_USER:
if (uap->who == 0)
uap->who = td->td_ucred->cr_uid;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
if (p->p_ucred->cr_uid == uap->who &&
!p_cansee(td, p)) {
error = donice(td, p, uap->prio);
found++;
}
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
break;
default:
error = EINVAL;
break;
}
if (found == 0 && error == 0)
error = ESRCH;
mtx_unlock(&Giant);
return (error);
}
/*
* Set "nice" for a process. Doesn't really understand threaded processes well
* but does try. Has the unfortunate side effect of making all the NICE
* values for a process's ksegrps the same.. This suggests that
* NICE valuse should be stored as a process nice and deltas for the ksegrps.
* (but not yet).
*/
static int
donice(struct thread *td, struct proc *p, int n)
{
int error;
int low = PRIO_MAX + 1;
struct ksegrp *kg;
PROC_LOCK_ASSERT(p, MA_OWNED);
if ((error = p_cansched(td, p)))
return (error);
if (n > PRIO_MAX)
n = PRIO_MAX;
if (n < PRIO_MIN)
n = PRIO_MIN;
/*
* Only allow nicing if to more than the lowest nice.
* e.g. nices of 4,3,2 allow nice to 3 but not 1
*/
FOREACH_KSEGRP_IN_PROC(p, kg) {
if (kg->kg_nice < low)
low = kg->kg_nice;
}
if (n < low && suser(td))
return (EACCES);
FOREACH_KSEGRP_IN_PROC(p, kg) {
sched_nice(kg, n);
}
return (0);
}
/* rtprio system call */
#ifndef _SYS_SYSPROTO_H_
struct rtprio_args {
int function;
pid_t pid;
struct rtprio *rtp;
};
#endif
/*
* Set realtime priority
*/
/*
* MPSAFE
*/
/* ARGSUSED */
int
rtprio(td, uap)
struct thread *td;
register struct rtprio_args *uap;
{
struct proc *curp = td->td_proc;
register struct proc *p;
struct rtprio rtp;
int error, cierror = 0;
/* Perform copyin before acquiring locks if needed. */
if (uap->function == RTP_SET)
cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
if (uap->pid == 0) {
p = curp;
PROC_LOCK(p);
} else {
p = pfind(uap->pid);
if (p == NULL)
return (ESRCH);
}
switch (uap->function) {
case RTP_LOOKUP:
if ((error = p_cansee(td, p)))
break;
mtx_lock_spin(&sched_lock);
pri_to_rtp(FIRST_KSEGRP_IN_PROC(p), &rtp);
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
case RTP_SET:
if ((error = p_cansched(td, p)) || (error = cierror))
break;
/* disallow setting rtprio in most cases if not superuser */
if (suser(td) != 0) {
/* can't set someone else's */
if (uap->pid) {
error = EPERM;
break;
}
/* can't set realtime priority */
/*
* Realtime priority has to be restricted for reasons which should be
* obvious. However, for idle priority, there is a potential for
* system deadlock if an idleprio process gains a lock on a resource
* that other processes need (and the idleprio process can't run
* due to a CPU-bound normal process). Fix me! XXX
*/
#if 0
if (RTP_PRIO_IS_REALTIME(rtp.type))
#endif
if (rtp.type != RTP_PRIO_NORMAL) {
error = EPERM;
break;
}
}
mtx_lock_spin(&sched_lock);
error = rtp_to_pri(&rtp, FIRST_KSEGRP_IN_PROC(p));
mtx_unlock_spin(&sched_lock);
break;
default:
error = EINVAL;
break;
}
PROC_UNLOCK(p);
return (error);
}
int
rtp_to_pri(struct rtprio *rtp, struct ksegrp *kg)
{
if (rtp->prio > RTP_PRIO_MAX)
return (EINVAL);
switch (RTP_PRIO_BASE(rtp->type)) {
case RTP_PRIO_REALTIME:
kg->kg_user_pri = PRI_MIN_REALTIME + rtp->prio;
break;
case RTP_PRIO_NORMAL:
kg->kg_user_pri = PRI_MIN_TIMESHARE + rtp->prio;
break;
case RTP_PRIO_IDLE:
kg->kg_user_pri = PRI_MIN_IDLE + rtp->prio;
break;
default:
return (EINVAL);
}
kg->kg_pri_class = rtp->type;
if (curthread->td_ksegrp == kg) {
curthread->td_base_pri = kg->kg_user_pri;
curthread->td_priority = kg->kg_user_pri; /* XXX dubious */
}
return (0);
}
void
pri_to_rtp(struct ksegrp *kg, struct rtprio *rtp)
{
switch (PRI_BASE(kg->kg_pri_class)) {
case PRI_REALTIME:
rtp->prio = kg->kg_user_pri - PRI_MIN_REALTIME;
break;
case PRI_TIMESHARE:
rtp->prio = kg->kg_user_pri - PRI_MIN_TIMESHARE;
break;
case PRI_IDLE:
rtp->prio = kg->kg_user_pri - PRI_MIN_IDLE;
break;
default:
break;
}
rtp->type = kg->kg_pri_class;
}
#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
#ifndef _SYS_SYSPROTO_H_
struct osetrlimit_args {
u_int which;
struct orlimit *rlp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
osetrlimit(td, uap)
struct thread *td;
register struct osetrlimit_args *uap;
{
struct orlimit olim;
struct rlimit lim;
int error;
if ((error = copyin(uap->rlp, &olim, sizeof(struct orlimit))))
return (error);
lim.rlim_cur = olim.rlim_cur;
lim.rlim_max = olim.rlim_max;
mtx_lock(&Giant);
error = dosetrlimit(td, uap->which, &lim);
mtx_unlock(&Giant);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct ogetrlimit_args {
u_int which;
struct orlimit *rlp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
ogetrlimit(td, uap)
struct thread *td;
register struct ogetrlimit_args *uap;
{
struct proc *p = td->td_proc;
struct orlimit olim;
int error;
if (uap->which >= RLIM_NLIMITS)
return (EINVAL);
mtx_lock(&Giant);
olim.rlim_cur = p->p_rlimit[uap->which].rlim_cur;
if (olim.rlim_cur == -1)
olim.rlim_cur = 0x7fffffff;
olim.rlim_max = p->p_rlimit[uap->which].rlim_max;
if (olim.rlim_max == -1)
olim.rlim_max = 0x7fffffff;
error = copyout(&olim, uap->rlp, sizeof(olim));
mtx_unlock(&Giant);
return (error);
}
#endif /* COMPAT_43 || COMPAT_SUNOS */
#ifndef _SYS_SYSPROTO_H_
struct __setrlimit_args {
u_int which;
struct rlimit *rlp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
setrlimit(td, uap)
struct thread *td;
register struct __setrlimit_args *uap;
{
struct rlimit alim;
int error;
if ((error = copyin(uap->rlp, &alim, sizeof (struct rlimit))))
return (error);
mtx_lock(&Giant);
error = dosetrlimit(td, uap->which, &alim);
mtx_unlock(&Giant);
return (error);
}
int
dosetrlimit(td, which, limp)
struct thread *td;
u_int which;
struct rlimit *limp;
{
struct proc *p = td->td_proc;
register struct rlimit *alimp;
int error;
GIANT_REQUIRED;
if (which >= RLIM_NLIMITS)
return (EINVAL);
alimp = &p->p_rlimit[which];
/*
* Preserve historical bugs by treating negative limits as unsigned.
*/
if (limp->rlim_cur < 0)
limp->rlim_cur = RLIM_INFINITY;
if (limp->rlim_max < 0)
limp->rlim_max = RLIM_INFINITY;
if (limp->rlim_cur > alimp->rlim_max ||
limp->rlim_max > alimp->rlim_max)
if ((error = suser_cred(td->td_ucred, PRISON_ROOT)))
return (error);
if (limp->rlim_cur > limp->rlim_max)
limp->rlim_cur = limp->rlim_max;
if (p->p_limit->p_refcnt > 1 &&
(p->p_limit->p_lflags & PL_SHAREMOD) == 0) {
p->p_limit->p_refcnt--;
p->p_limit = limcopy(p->p_limit);
alimp = &p->p_rlimit[which];
}
switch (which) {
case RLIMIT_CPU:
mtx_lock_spin(&sched_lock);
p->p_cpulimit = limp->rlim_cur;
mtx_unlock_spin(&sched_lock);
break;
case RLIMIT_DATA:
if (limp->rlim_cur > maxdsiz)
limp->rlim_cur = maxdsiz;
if (limp->rlim_max > maxdsiz)
limp->rlim_max = maxdsiz;
break;
case RLIMIT_STACK:
if (limp->rlim_cur > maxssiz)
limp->rlim_cur = maxssiz;
if (limp->rlim_max > maxssiz)
limp->rlim_max = maxssiz;
/*
* Stack is allocated to the max at exec time with only
* "rlim_cur" bytes accessible. If stack limit is going
* up make more accessible, if going down make inaccessible.
*/
if (limp->rlim_cur != alimp->rlim_cur) {
vm_offset_t addr;
vm_size_t size;
vm_prot_t prot;
if (limp->rlim_cur > alimp->rlim_cur) {
prot = p->p_sysent->sv_stackprot;
size = limp->rlim_cur - alimp->rlim_cur;
addr = p->p_sysent->sv_usrstack -
limp->rlim_cur;
} else {
prot = VM_PROT_NONE;
size = alimp->rlim_cur - limp->rlim_cur;
addr = p->p_sysent->sv_usrstack -
alimp->rlim_cur;
}
addr = trunc_page(addr);
size = round_page(size);
(void) vm_map_protect(&p->p_vmspace->vm_map,
addr, addr+size, prot, FALSE);
}
break;
case RLIMIT_NOFILE:
if (limp->rlim_cur > maxfilesperproc)
limp->rlim_cur = maxfilesperproc;
if (limp->rlim_max > maxfilesperproc)
limp->rlim_max = maxfilesperproc;
break;
case RLIMIT_NPROC:
if (limp->rlim_cur > maxprocperuid)
limp->rlim_cur = maxprocperuid;
if (limp->rlim_max > maxprocperuid)
limp->rlim_max = maxprocperuid;
if (limp->rlim_cur < 1)
limp->rlim_cur = 1;
if (limp->rlim_max < 1)
limp->rlim_max = 1;
break;
}
*alimp = *limp;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct __getrlimit_args {
u_int which;
struct rlimit *rlp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
getrlimit(td, uap)
struct thread *td;
register struct __getrlimit_args *uap;
{
int error;
struct proc *p = td->td_proc;
if (uap->which >= RLIM_NLIMITS)
return (EINVAL);
mtx_lock(&Giant);
error = copyout(&p->p_rlimit[uap->which], uap->rlp,
sizeof (struct rlimit));
mtx_unlock(&Giant);
return(error);
}
/*
* Transform the running time and tick information in proc p into user,
* system, and interrupt time usage.
*/
void
calcru(p, up, sp, ip)
struct proc *p;
struct timeval *up;
struct timeval *sp;
struct timeval *ip;
{
/* {user, system, interrupt, total} {ticks, usec}; previous tu: */
u_int64_t ut, uu, st, su, it, iu, tt, tu, ptu;
u_int64_t uut = 0, sut = 0, iut = 0;
int s;
struct timeval tv;
struct bintime bt;
struct kse *ke;
struct ksegrp *kg;
mtx_assert(&sched_lock, MA_OWNED);
/* XXX: why spl-protect ? worst case is an off-by-one report */
FOREACH_KSEGRP_IN_PROC(p, kg) {
/* we could accumulate per ksegrp and per process here*/
FOREACH_KSE_IN_GROUP(kg, ke) {
s = splstatclock();
ut = ke->ke_uticks;
st = ke->ke_sticks;
it = ke->ke_iticks;
splx(s);
tt = ut + st + it;
if (tt == 0) {
st = 1;
tt = 1;
}
if (ke == curthread->td_kse) {
/*
* Adjust for the current time slice. This is actually fairly
* important since the error here is on the order of a time
* quantum, which is much greater than the sampling error.
* XXXKSE use a different test due to threads on other
* processors also being 'current'.
*/
binuptime(&bt);
bintime_sub(&bt, PCPU_PTR(switchtime));
bintime_add(&bt, &p->p_runtime);
} else {
bt = p->p_runtime;
}
bintime2timeval(&bt, &tv);
tu = (u_int64_t)tv.tv_sec * 1000000 + tv.tv_usec;
ptu = ke->ke_uu + ke->ke_su + ke->ke_iu;
if (tu < ptu || (int64_t)tu < 0) {
/* XXX no %qd in kernel. Truncate. */
printf("calcru: negative time of %ld usec for pid %d (%s)\n",
(long)tu, p->p_pid, p->p_comm);
tu = ptu;
}
/* Subdivide tu. */
uu = (tu * ut) / tt;
su = (tu * st) / tt;
iu = tu - uu - su;
/* Enforce monotonicity. */
if (uu < ke->ke_uu || su < ke->ke_su || iu < ke->ke_iu) {
if (uu < ke->ke_uu)
uu = ke->ke_uu;
else if (uu + ke->ke_su + ke->ke_iu > tu)
uu = tu - ke->ke_su - ke->ke_iu;
if (st == 0)
su = ke->ke_su;
else {
su = ((tu - uu) * st) / (st + it);
if (su < ke->ke_su)
su = ke->ke_su;
else if (uu + su + ke->ke_iu > tu)
su = tu - uu - ke->ke_iu;
}
KASSERT(uu + su + ke->ke_iu <= tu,
("calcru: monotonisation botch 1"));
iu = tu - uu - su;
KASSERT(iu >= ke->ke_iu,
("calcru: monotonisation botch 2"));
}
ke->ke_uu = uu;
ke->ke_su = su;
ke->ke_iu = iu;
uut += uu;
sut += su;
iut += iu;
} /* end kse loop */
} /* end kseg loop */
up->tv_sec = uut / 1000000;
up->tv_usec = uut % 1000000;
sp->tv_sec = sut / 1000000;
sp->tv_usec = sut % 1000000;
if (ip != NULL) {
ip->tv_sec = iut / 1000000;
ip->tv_usec = iut % 1000000;
}
}
#ifndef _SYS_SYSPROTO_H_
struct getrusage_args {
int who;
struct rusage *rusage;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
getrusage(td, uap)
register struct thread *td;
register struct getrusage_args *uap;
{
struct proc *p = td->td_proc;
register struct rusage *rup;
int error = 0;
mtx_lock(&Giant);
switch (uap->who) {
case RUSAGE_SELF:
rup = &p->p_stats->p_ru;
mtx_lock_spin(&sched_lock);
calcru(p, &rup->ru_utime, &rup->ru_stime, NULL);
mtx_unlock_spin(&sched_lock);
break;
case RUSAGE_CHILDREN:
rup = &p->p_stats->p_cru;
break;
default:
rup = NULL;
error = EINVAL;
break;
}
mtx_unlock(&Giant);
if (error == 0) {
/* XXX Unlocked access to p_stats->p_ru or p_cru. */
error = copyout(rup, uap->rusage, sizeof (struct rusage));
}
return(error);
}
void
ruadd(ru, ru2)
register struct rusage *ru, *ru2;
{
register long *ip, *ip2;
register int i;
timevaladd(&ru->ru_utime, &ru2->ru_utime);
timevaladd(&ru->ru_stime, &ru2->ru_stime);
if (ru->ru_maxrss < ru2->ru_maxrss)
ru->ru_maxrss = ru2->ru_maxrss;
ip = &ru->ru_first; ip2 = &ru2->ru_first;
for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
*ip++ += *ip2++;
}
/*
* Make a copy of the plimit structure.
* We share these structures copy-on-write after fork,
* and copy when a limit is changed.
*/
struct plimit *
limcopy(lim)
struct plimit *lim;
{
register struct plimit *copy;
MALLOC(copy, struct plimit *, sizeof(struct plimit),
M_SUBPROC, 0);
bcopy(lim->pl_rlimit, copy->pl_rlimit, sizeof(struct plimit));
copy->p_lflags = 0;
copy->p_refcnt = 1;
return (copy);
}
/*
* Find the uidinfo structure for a uid. This structure is used to
* track the total resource consumption (process count, socket buffer
* size, etc.) for the uid and impose limits.
*/
void
uihashinit()
{
uihashtbl = hashinit(maxproc / 16, M_UIDINFO, &uihash);
mtx_init(&uihashtbl_mtx, "uidinfo hash", NULL, MTX_DEF);
}
/*
* lookup a uidinfo struct for the parameter uid.
* uihashtbl_mtx must be locked.
*/
static struct uidinfo *
uilookup(uid)
uid_t uid;
{
struct uihashhead *uipp;
struct uidinfo *uip;
mtx_assert(&uihashtbl_mtx, MA_OWNED);
uipp = UIHASH(uid);
LIST_FOREACH(uip, uipp, ui_hash)
if (uip->ui_uid == uid)
break;
return (uip);
}
/*
* Find or allocate a struct uidinfo for a particular uid.
* Increase refcount on uidinfo struct returned.
* uifree() should be called on a struct uidinfo when released.
*/
struct uidinfo *
uifind(uid)
uid_t uid;
{
struct uidinfo *uip;
mtx_lock(&uihashtbl_mtx);
uip = uilookup(uid);
if (uip == NULL) {
struct uidinfo *old_uip;
mtx_unlock(&uihashtbl_mtx);
uip = malloc(sizeof(*uip), M_UIDINFO, M_ZERO);
mtx_lock(&uihashtbl_mtx);
/*
* There's a chance someone created our uidinfo while we
* were in malloc and not holding the lock, so we have to
* make sure we don't insert a duplicate uidinfo
*/
if ((old_uip = uilookup(uid)) != NULL) {
/* someone else beat us to it */
free(uip, M_UIDINFO);
uip = old_uip;
} else {
uip->ui_mtxp = mtx_pool_alloc();
uip->ui_uid = uid;
LIST_INSERT_HEAD(UIHASH(uid), uip, ui_hash);
}
}
uihold(uip);
mtx_unlock(&uihashtbl_mtx);
return (uip);
}
/*
* Place another refcount on a uidinfo struct.
*/
void
uihold(uip)
struct uidinfo *uip;
{
UIDINFO_LOCK(uip);
uip->ui_ref++;
UIDINFO_UNLOCK(uip);
}
/*-
* Since uidinfo structs have a long lifetime, we use an
* opportunistic refcounting scheme to avoid locking the lookup hash
* for each release.
*
* If the refcount hits 0, we need to free the structure,
* which means we need to lock the hash.
* Optimal case:
* After locking the struct and lowering the refcount, if we find
* that we don't need to free, simply unlock and return.
* Suboptimal case:
* If refcount lowering results in need to free, bump the count
* back up, loose the lock and aquire the locks in the proper
* order to try again.
*/
void
uifree(uip)
struct uidinfo *uip;
{
/* Prepare for optimal case. */
UIDINFO_LOCK(uip);
if (--uip->ui_ref != 0) {
UIDINFO_UNLOCK(uip);
return;
}
/* Prepare for suboptimal case. */
uip->ui_ref++;
UIDINFO_UNLOCK(uip);
mtx_lock(&uihashtbl_mtx);
UIDINFO_LOCK(uip);
/*
* We must subtract one from the count again because we backed out
* our initial subtraction before dropping the lock.
* Since another thread may have added a reference after we dropped the
* initial lock we have to test for zero again.
*/
if (--uip->ui_ref == 0) {
LIST_REMOVE(uip, ui_hash);
mtx_unlock(&uihashtbl_mtx);
if (uip->ui_sbsize != 0)
/* XXX no %qd in kernel. Truncate. */
printf("freeing uidinfo: uid = %d, sbsize = %ld\n",
uip->ui_uid, (long)uip->ui_sbsize);
if (uip->ui_proccnt != 0)
printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
uip->ui_uid, uip->ui_proccnt);
UIDINFO_UNLOCK(uip);
FREE(uip, M_UIDINFO);
return;
}
mtx_unlock(&uihashtbl_mtx);
UIDINFO_UNLOCK(uip);
}
/*
* Change the count associated with number of processes
* a given user is using. When 'max' is 0, don't enforce a limit
*/
int
chgproccnt(uip, diff, max)
struct uidinfo *uip;
int diff;
int max;
{
UIDINFO_LOCK(uip);
/* don't allow them to exceed max, but allow subtraction */
if (diff > 0 && uip->ui_proccnt + diff > max && max != 0) {
UIDINFO_UNLOCK(uip);
return (0);
}
uip->ui_proccnt += diff;
if (uip->ui_proccnt < 0)
printf("negative proccnt for uid = %d\n", uip->ui_uid);
UIDINFO_UNLOCK(uip);
return (1);
}
/*
* Change the total socket buffer size a user has used.
*/
int
chgsbsize(uip, hiwat, to, max)
struct uidinfo *uip;
u_int *hiwat;
u_int to;
rlim_t max;
{
rlim_t new;
int s;
s = splnet();
UIDINFO_LOCK(uip);
new = uip->ui_sbsize + to - *hiwat;
/* don't allow them to exceed max, but allow subtraction */
if (to > *hiwat && new > max) {
splx(s);
UIDINFO_UNLOCK(uip);
return (0);
}
uip->ui_sbsize = new;
*hiwat = to;
if (uip->ui_sbsize < 0)
printf("negative sbsize for uid = %d\n", uip->ui_uid);
splx(s);
UIDINFO_UNLOCK(uip);
return (1);
}
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