1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 23 /* All Rights Reserved */ 24 25 26 /* 27 * Copyright 2005 Sun Microsystems, Inc. All rights reserved. 28 * Use is subject to license terms. 29 */ 30 31 #pragma ident "%Z%%M% %I% %E% SMI" 32 33 #include <sys/param.h> 34 #include <sys/types.h> 35 #include <sys/sysmacros.h> 36 #include <sys/systm.h> 37 #include <sys/errno.h> 38 #include <sys/signal.h> 39 #include <sys/proc.h> 40 #include <sys/time.h> 41 #include <sys/cmn_err.h> 42 #include <sys/debug.h> 43 44 static void 45 sigalarm2proc(void *arg) 46 { 47 proc_t *p = arg; 48 49 mutex_enter(&p->p_lock); 50 p->p_alarmid = 0; 51 sigtoproc(p, NULL, SIGALRM); 52 mutex_exit(&p->p_lock); 53 } 54 55 int 56 alarm(int deltat) 57 { 58 proc_t *p = ttoproc(curthread); 59 clock_t del = 0; 60 clock_t ret; 61 timeout_id_t tmp_id; 62 63 /* 64 * We must single-thread this code relative to other 65 * lwps in the same process also performing an alarm(). 66 * The mutex dance in the while loop is necessary because 67 * we cannot call untimeout() while holding a lock that 68 * is grabbed by the timeout function, sigalarm2proc(). 69 * We can, however, hold p->p_lock across realtime_timeout(). 70 */ 71 mutex_enter(&p->p_lock); 72 while ((tmp_id = p->p_alarmid) != 0) { 73 p->p_alarmid = 0; 74 mutex_exit(&p->p_lock); 75 del = untimeout(tmp_id); 76 mutex_enter(&p->p_lock); 77 } 78 79 if (del < 0) 80 ret = 0; 81 else 82 ret = (del + hz - 1) / hz; /* convert to seconds */ 83 84 /* 85 * Our implementation defined limit for alarm is 86 * INT_MAX / hz. Anything larger gets truncated 87 * to that limit. If deltat is negative we can 88 * assume a wrap has occurred so peg deltat in 89 * that case too. 90 */ 91 if (deltat > (INT_MAX / hz) || deltat < 0) 92 deltat = INT_MAX / hz; 93 94 if (deltat) 95 p->p_alarmid = realtime_timeout(sigalarm2proc, p, deltat * hz); 96 mutex_exit(&p->p_lock); 97 return (ret); 98 } 99