kern_kthread.c revision 1.39
1/* $NetBSD: kern_kthread.c,v 1.39 2012/09/01 00:26:37 matt Exp $ */ 2 3/*- 4 * Copyright (c) 1998, 1999, 2007, 2009 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33#include <sys/cdefs.h> 34__KERNEL_RCSID(0, "$NetBSD: kern_kthread.c,v 1.39 2012/09/01 00:26:37 matt Exp $"); 35 36#include <sys/param.h> 37#include <sys/systm.h> 38#include <sys/kernel.h> 39#include <sys/kthread.h> 40#include <sys/mutex.h> 41#include <sys/sched.h> 42#include <sys/kmem.h> 43 44#include <uvm/uvm_extern.h> 45 46static lwp_t * kthread_jtarget; 47static kmutex_t kthread_lock; 48static kcondvar_t kthread_cv; 49 50void 51kthread_sysinit(void) 52{ 53 54 mutex_init(&kthread_lock, MUTEX_DEFAULT, IPL_NONE); 55 cv_init(&kthread_cv, "kthrwait"); 56 kthread_jtarget = NULL; 57} 58 59/* 60 * kthread_create: create a kernel thread, that is, system-only LWP. 61 */ 62int 63kthread_create(pri_t pri, int flag, struct cpu_info *ci, 64 void (*func)(void *), void *arg, lwp_t **lp, const char *fmt, ...) 65{ 66 lwp_t *l; 67 vaddr_t uaddr; 68 int error, lc; 69 va_list ap; 70 71 KASSERT((flag & KTHREAD_INTR) == 0 || (flag & KTHREAD_MPSAFE) != 0); 72 73 uaddr = uvm_uarea_system_alloc( 74 (flag & (KTHREAD_INTR|KTHREAD_IDLE)) == KTHREAD_IDLE ? ci : NULL); 75 if (uaddr == 0) { 76 return ENOMEM; 77 } 78 if ((flag & KTHREAD_TS) != 0) { 79 lc = SCHED_OTHER; 80 } else { 81 lc = SCHED_RR; 82 } 83 84 error = lwp_create(&lwp0, &proc0, uaddr, LWP_DETACHED, NULL, 85 0, func, arg, &l, lc); 86 if (error) { 87 uvm_uarea_system_free(uaddr); 88 return error; 89 } 90 if (fmt != NULL) { 91 l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP); 92 if (l->l_name == NULL) { 93 kthread_destroy(l); 94 return ENOMEM; 95 } 96 va_start(ap, fmt); 97 vsnprintf(l->l_name, MAXCOMLEN, fmt, ap); 98 va_end(ap); 99 } 100 101 /* 102 * Set parameters. 103 */ 104 if (pri == PRI_NONE) { 105 if ((flag & KTHREAD_TS) != 0) { 106 /* Maximum user priority level. */ 107 pri = MAXPRI_USER; 108 } else { 109 /* Minimum kernel priority level. */ 110 pri = PRI_KTHREAD; 111 } 112 } 113 mutex_enter(proc0.p_lock); 114 lwp_lock(l); 115 l->l_priority = pri; 116 if (ci != NULL) { 117 if (ci != l->l_cpu) { 118 lwp_unlock_to(l, ci->ci_schedstate.spc_mutex); 119 lwp_lock(l); 120 } 121 l->l_pflag |= LP_BOUND; 122 l->l_cpu = ci; 123 } 124 125 if ((flag & KTHREAD_MUSTJOIN) != 0) { 126 KASSERT(lp != NULL); 127 l->l_pflag |= LP_MUSTJOIN; 128 } 129 if ((flag & KTHREAD_INTR) != 0) { 130 l->l_pflag |= LP_INTR; 131 } 132 if ((flag & KTHREAD_MPSAFE) == 0) { 133 l->l_pflag &= ~LP_MPSAFE; 134 } 135 136 /* 137 * Set the new LWP running, unless the caller has requested 138 * otherwise. 139 */ 140 if ((flag & KTHREAD_IDLE) == 0) { 141 l->l_stat = LSRUN; 142 sched_enqueue(l, false); 143 lwp_unlock(l); 144 } else { 145 if (ci != NULL) 146 lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock); 147 else 148 lwp_unlock(l); 149 } 150 mutex_exit(proc0.p_lock); 151 152 /* All done! */ 153 if (lp != NULL) { 154 *lp = l; 155 } 156 return 0; 157} 158 159/* 160 * Cause a kernel thread to exit. Assumes the exiting thread is the 161 * current context. 162 */ 163void 164kthread_exit(int ecode) 165{ 166 const char *name; 167 lwp_t *l = curlwp; 168 169 /* We can't do much with the exit code, so just report it. */ 170 if (ecode != 0) { 171 if ((name = l->l_name) == NULL) 172 name = "unnamed"; 173 printf("WARNING: kthread `%s' (%d) exits with status %d\n", 174 name, l->l_lid, ecode); 175 } 176 177 /* Barrier for joining. */ 178 if (l->l_pflag & LP_MUSTJOIN) { 179 mutex_enter(&kthread_lock); 180 while (kthread_jtarget != l) { 181 cv_wait(&kthread_cv, &kthread_lock); 182 } 183 kthread_jtarget = NULL; 184 cv_broadcast(&kthread_cv); 185 mutex_exit(&kthread_lock); 186 } 187 188 /* And exit.. */ 189 lwp_exit(l); 190 panic("kthread_exit"); 191} 192 193/* 194 * Destroy an inactive kthread. The kthread must be in the LSIDL state. 195 */ 196void 197kthread_destroy(lwp_t *l) 198{ 199 200 KASSERT((l->l_flag & LW_SYSTEM) != 0); 201 KASSERT(l->l_stat == LSIDL); 202 203 lwp_exit(l); 204} 205 206/* 207 * Wait for a kthread to exit, as pthread_join(). 208 */ 209int 210kthread_join(lwp_t *l) 211{ 212 213 KASSERT((l->l_flag & LW_SYSTEM) != 0); 214 215 /* 216 * - Wait if some other thread has occupied the target. 217 * - Specify our kthread as a target and notify it. 218 * - Wait for the target kthread to notify us. 219 */ 220 mutex_enter(&kthread_lock); 221 while (kthread_jtarget) { 222 cv_wait(&kthread_cv, &kthread_lock); 223 } 224 kthread_jtarget = l; 225 cv_broadcast(&kthread_cv); 226 while (kthread_jtarget == l) { 227 cv_wait(&kthread_cv, &kthread_lock); 228 } 229 mutex_exit(&kthread_lock); 230 231 return 0; 232} 233