1 /* $NetBSD: kern_uidinfo.c,v 1.4 2009/01/11 02:45:52 christos 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 1.4 2009/01/11 02:45:52 christos 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 47 static SLIST_HEAD(uihashhead, uidinfo) *uihashtbl; 48 static u_long uihash; 49 50 #define UIHASH(uid) (&uihashtbl[(uid) & uihash]) 51 52 void 53 uid_init(void) 54 { 55 56 /* 57 * In case of MP system, SLIST_FOREACH would force a cache line 58 * write-back for every modified 'uidinfo', thus we try to keep the 59 * lists short. 60 */ 61 const u_int uihash_sz = (maxproc > 1 ? 1024 : 64); 62 63 uihashtbl = hashinit(uihash_sz, HASH_SLIST, true, &uihash); 64 65 /* 66 * Ensure that uid 0 is always in the user hash table, as 67 * sbreserve() expects it available from interrupt context. 68 */ 69 (void)uid_find(0); 70 } 71 72 struct uidinfo * 73 uid_find(uid_t uid) 74 { 75 struct uidinfo *uip, *uip_first, *newuip; 76 struct uihashhead *uipp; 77 78 uipp = UIHASH(uid); 79 newuip = NULL; 80 81 /* 82 * To make insertion atomic, abstraction of SLIST will be violated. 83 */ 84 uip_first = uipp->slh_first; 85 again: 86 SLIST_FOREACH(uip, uipp, ui_hash) { 87 if (uip->ui_uid != uid) 88 continue; 89 if (newuip != NULL) 90 kmem_free(newuip, sizeof(*newuip)); 91 return uip; 92 } 93 if (newuip == NULL) 94 newuip = kmem_zalloc(sizeof(*newuip), KM_SLEEP); 95 newuip->ui_uid = uid; 96 97 /* 98 * If atomic insert is unsuccessful, another thread might be 99 * allocated this 'uid', thus full re-check is needed. 100 */ 101 newuip->ui_hash.sle_next = uip_first; 102 membar_producer(); 103 uip = atomic_cas_ptr(&uipp->slh_first, uip_first, newuip); 104 if (uip != uip_first) { 105 uip_first = uip; 106 goto again; 107 } 108 109 return newuip; 110 } 111 112 /* 113 * Change the count associated with number of processes 114 * a given user is using. 115 */ 116 int 117 chgproccnt(uid_t uid, int diff) 118 { 119 struct uidinfo *uip; 120 long proccnt; 121 122 uip = uid_find(uid); 123 proccnt = atomic_add_long_nv(&uip->ui_proccnt, diff); 124 KASSERT(proccnt >= 0); 125 return proccnt; 126 } 127 128 int 129 chgsbsize(struct uidinfo *uip, u_long *hiwat, u_long to, rlim_t xmax) 130 { 131 rlim_t nsb; 132 const long diff = to - *hiwat; 133 134 nsb = (rlim_t)atomic_add_long_nv((long *)&uip->ui_sbsize, diff); 135 if (diff > 0 && nsb > xmax) { 136 atomic_add_long((long *)&uip->ui_sbsize, -diff); 137 return 0; 138 } 139 *hiwat = to; 140 return 1; 141 } 142