1 /* $NetBSD: kern_kthread.c,v 1.34 2011/05/24 18:18:22 joerg 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 1.34 2011/05/24 18:18:22 joerg 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 #include <machine/stdarg.h> 46 47 static lwp_t * kthread_jtarget; 48 static kmutex_t kthread_lock; 49 static kcondvar_t kthread_cv; 50 51 void 52 kthread_sysinit(void) 53 { 54 55 mutex_init(&kthread_lock, MUTEX_DEFAULT, IPL_NONE); 56 cv_init(&kthread_cv, "kthrwait"); 57 kthread_jtarget = NULL; 58 } 59 60 /* 61 * kthread_create: create a kernel thread, that is, system-only LWP. 62 */ 63 int 64 kthread_create(pri_t pri, int flag, struct cpu_info *ci, 65 void (*func)(void *), void *arg, lwp_t **lp, const char *fmt, ...) 66 { 67 lwp_t *l; 68 vaddr_t uaddr; 69 int error, lc; 70 va_list ap; 71 72 KASSERT((flag & KTHREAD_INTR) == 0 || (flag & KTHREAD_MPSAFE) != 0); 73 74 uaddr = uvm_uarea_system_alloc(); 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_JOINABLE) != 0) { 126 KASSERT(lp != NULL); 127 l->l_pflag |= LP_JOINABLE; 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 lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock); 146 mutex_exit(proc0.p_lock); 147 148 /* All done! */ 149 if (lp != NULL) { 150 *lp = l; 151 } 152 return 0; 153 } 154 155 /* 156 * Cause a kernel thread to exit. Assumes the exiting thread is the 157 * current context. 158 */ 159 void 160 kthread_exit(int ecode) 161 { 162 const char *name; 163 lwp_t *l = curlwp; 164 165 /* We can't do much with the exit code, so just report it. */ 166 if (ecode != 0) { 167 if ((name = l->l_name) == NULL) 168 name = "unnamed"; 169 printf("WARNING: kthread `%s' (%d) exits with status %d\n", 170 name, l->l_lid, ecode); 171 } 172 173 /* Barrier for joining. */ 174 if (l->l_pflag & LP_JOINABLE) { 175 mutex_enter(&kthread_lock); 176 while (kthread_jtarget != l) { 177 cv_wait(&kthread_cv, &kthread_lock); 178 } 179 kthread_jtarget = NULL; 180 cv_broadcast(&kthread_cv); 181 mutex_exit(&kthread_lock); 182 } 183 184 /* And exit.. */ 185 lwp_exit(l); 186 panic("kthread_exit"); 187 } 188 189 /* 190 * Destroy an inactive kthread. The kthread must be in the LSIDL state. 191 */ 192 void 193 kthread_destroy(lwp_t *l) 194 { 195 196 KASSERT((l->l_flag & LW_SYSTEM) != 0); 197 KASSERT(l->l_stat == LSIDL); 198 199 lwp_exit(l); 200 } 201 202 /* 203 * Wait for a kthread to exit, as pthread_join(). 204 */ 205 int 206 kthread_join(lwp_t *l) 207 { 208 209 KASSERT((l->l_flag & LW_SYSTEM) != 0); 210 211 /* 212 * - Wait if some other thread has occupied the target. 213 * - Speicfy our kthread as a target and notify it. 214 * - Wait for the target kthread to notify us. 215 */ 216 mutex_enter(&kthread_lock); 217 while (kthread_jtarget) { 218 cv_wait(&kthread_cv, &kthread_lock); 219 } 220 kthread_jtarget = l; 221 cv_broadcast(&kthread_cv); 222 while (kthread_jtarget == l) { 223 cv_wait(&kthread_cv, &kthread_lock); 224 } 225 mutex_exit(&kthread_lock); 226 227 return 0; 228 } 229