NetBSD/sys/kern/kern_uidinfo.c

143 lines
4.2 KiB
C

/* $NetBSD: kern_uidinfo.c,v 1.5 2009/03/22 00:49:13 ad Exp $ */
/*-
* 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. 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.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_uidinfo.c,v 1.5 2009/03/22 00:49:13 ad Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/atomic.h>
#include <sys/uidinfo.h>
#include <sys/cpu.h>
static SLIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long uihash;
#define UIHASH(uid) (&uihashtbl[(uid) & uihash])
void
uid_init(void)
{
/*
* In case of MP system, SLIST_FOREACH would force a cache line
* write-back for every modified 'uidinfo', thus we try to keep the
* lists short.
*/
const u_int uihash_sz = (maxcpus > 1 ? 1024 : 64);
uihashtbl = hashinit(uihash_sz, HASH_SLIST, true, &uihash);
/*
* Ensure that uid 0 is always in the user hash table, as
* sbreserve() expects it available from interrupt context.
*/
(void)uid_find(0);
}
struct uidinfo *
uid_find(uid_t uid)
{
struct uidinfo *uip, *uip_first, *newuip;
struct uihashhead *uipp;
uipp = UIHASH(uid);
newuip = NULL;
/*
* To make insertion atomic, abstraction of SLIST will be violated.
*/
uip_first = uipp->slh_first;
again:
SLIST_FOREACH(uip, uipp, ui_hash) {
if (uip->ui_uid != uid)
continue;
if (newuip != NULL)
kmem_free(newuip, sizeof(*newuip));
return uip;
}
if (newuip == NULL)
newuip = kmem_zalloc(sizeof(*newuip), KM_SLEEP);
newuip->ui_uid = uid;
/*
* If atomic insert is unsuccessful, another thread might be
* allocated this 'uid', thus full re-check is needed.
*/
newuip->ui_hash.sle_next = uip_first;
membar_producer();
uip = atomic_cas_ptr(&uipp->slh_first, uip_first, newuip);
if (uip != uip_first) {
uip_first = uip;
goto again;
}
return newuip;
}
/*
* Change the count associated with number of processes
* a given user is using.
*/
int
chgproccnt(uid_t uid, int diff)
{
struct uidinfo *uip;
long proccnt;
uip = uid_find(uid);
proccnt = atomic_add_long_nv(&uip->ui_proccnt, diff);
KASSERT(proccnt >= 0);
return proccnt;
}
int
chgsbsize(struct uidinfo *uip, u_long *hiwat, u_long to, rlim_t xmax)
{
rlim_t nsb;
const long diff = to - *hiwat;
nsb = (rlim_t)atomic_add_long_nv((long *)&uip->ui_sbsize, diff);
if (diff > 0 && nsb > xmax) {
atomic_add_long((long *)&uip->ui_sbsize, -diff);
return 0;
}
*hiwat = to;
return 1;
}