1 /* $NetBSD: kern_uidinfo.c,v 1.5 2009/03/22 00:49:13 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 1982, 1986, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/cdefs.h> 38 __KERNEL_RCSID(0, "$NetBSD: kern_uidinfo.c,v 1.5 2009/03/22 00:49:13 ad Exp $"); 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kmem.h> 43 #include <sys/proc.h> 44 #include <sys/atomic.h> 45 #include <sys/uidinfo.h> 46 #include <sys/cpu.h> 47 48 static SLIST_HEAD(uihashhead, uidinfo) *uihashtbl; 49 static u_long uihash; 50 51 #define UIHASH(uid) (&uihashtbl[(uid) & uihash]) 52 53 void 54 uid_init(void) 55 { 56 57 /* 58 * In case of MP system, SLIST_FOREACH would force a cache line 59 * write-back for every modified 'uidinfo', thus we try to keep the 60 * lists short. 61 */ 62 const u_int uihash_sz = (maxcpus > 1 ? 1024 : 64); 63 64 uihashtbl = hashinit(uihash_sz, HASH_SLIST, true, &uihash); 65 66 /* 67 * Ensure that uid 0 is always in the user hash table, as 68 * sbreserve() expects it available from interrupt context. 69 */ 70 (void)uid_find(0); 71 } 72 73 struct uidinfo * 74 uid_find(uid_t uid) 75 { 76 struct uidinfo *uip, *uip_first, *newuip; 77 struct uihashhead *uipp; 78 79 uipp = UIHASH(uid); 80 newuip = NULL; 81 82 /* 83 * To make insertion atomic, abstraction of SLIST will be violated. 84 */ 85 uip_first = uipp->slh_first; 86 again: 87 SLIST_FOREACH(uip, uipp, ui_hash) { 88 if (uip->ui_uid != uid) 89 continue; 90 if (newuip != NULL) 91 kmem_free(newuip, sizeof(*newuip)); 92 return uip; 93 } 94 if (newuip == NULL) 95 newuip = kmem_zalloc(sizeof(*newuip), KM_SLEEP); 96 newuip->ui_uid = uid; 97 98 /* 99 * If atomic insert is unsuccessful, another thread might be 100 * allocated this 'uid', thus full re-check is needed. 101 */ 102 newuip->ui_hash.sle_next = uip_first; 103 membar_producer(); 104 uip = atomic_cas_ptr(&uipp->slh_first, uip_first, newuip); 105 if (uip != uip_first) { 106 uip_first = uip; 107 goto again; 108 } 109 110 return newuip; 111 } 112 113 /* 114 * Change the count associated with number of processes 115 * a given user is using. 116 */ 117 int 118 chgproccnt(uid_t uid, int diff) 119 { 120 struct uidinfo *uip; 121 long proccnt; 122 123 uip = uid_find(uid); 124 proccnt = atomic_add_long_nv(&uip->ui_proccnt, diff); 125 KASSERT(proccnt >= 0); 126 return proccnt; 127 } 128 129 int 130 chgsbsize(struct uidinfo *uip, u_long *hiwat, u_long to, rlim_t xmax) 131 { 132 rlim_t nsb; 133 const long diff = to - *hiwat; 134 135 nsb = (rlim_t)atomic_add_long_nv((long *)&uip->ui_sbsize, diff); 136 if (diff > 0 && nsb > xmax) { 137 atomic_add_long((long *)&uip->ui_sbsize, -diff); 138 return 0; 139 } 140 *hiwat = to; 141 return 1; 142 } 143