1 /* $NetBSD: kern_kthread.c,v 1.36 2011/08/07 14:03:16 rmind 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 1.36 2011/08/07 14:03:16 rmind 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 46 static lwp_t * kthread_jtarget; 47 static kmutex_t kthread_lock; 48 static kcondvar_t kthread_cv; 49 50 void 51 kthread_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 */ 62 int 63 kthread_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 if (uaddr == 0) { 75 return ENOMEM; 76 } 77 if ((flag & KTHREAD_TS) != 0) { 78 lc = SCHED_OTHER; 79 } else { 80 lc = SCHED_RR; 81 } 82 83 error = lwp_create(&lwp0, &proc0, uaddr, LWP_DETACHED, NULL, 84 0, func, arg, &l, lc); 85 if (error) { 86 uvm_uarea_system_free(uaddr); 87 return error; 88 } 89 if (fmt != NULL) { 90 l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP); 91 if (l->l_name == NULL) { 92 kthread_destroy(l); 93 return ENOMEM; 94 } 95 va_start(ap, fmt); 96 vsnprintf(l->l_name, MAXCOMLEN, fmt, ap); 97 va_end(ap); 98 } 99 100 /* 101 * Set parameters. 102 */ 103 if (pri == PRI_NONE) { 104 if ((flag & KTHREAD_TS) != 0) { 105 /* Maximum user priority level. */ 106 pri = MAXPRI_USER; 107 } else { 108 /* Minimum kernel priority level. */ 109 pri = PRI_KTHREAD; 110 } 111 } 112 mutex_enter(proc0.p_lock); 113 lwp_lock(l); 114 l->l_priority = pri; 115 if (ci != NULL) { 116 if (ci != l->l_cpu) { 117 lwp_unlock_to(l, ci->ci_schedstate.spc_mutex); 118 lwp_lock(l); 119 } 120 l->l_pflag |= LP_BOUND; 121 l->l_cpu = ci; 122 } 123 124 if ((flag & KTHREAD_MUSTJOIN) != 0) { 125 KASSERT(lp != NULL); 126 l->l_pflag |= LP_MUSTJOIN; 127 } 128 if ((flag & KTHREAD_INTR) != 0) { 129 l->l_pflag |= LP_INTR; 130 } 131 if ((flag & KTHREAD_MPSAFE) == 0) { 132 l->l_pflag &= ~LP_MPSAFE; 133 } 134 135 /* 136 * Set the new LWP running, unless the caller has requested 137 * otherwise. 138 */ 139 if ((flag & KTHREAD_IDLE) == 0) { 140 l->l_stat = LSRUN; 141 sched_enqueue(l, false); 142 lwp_unlock(l); 143 } else 144 lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock); 145 mutex_exit(proc0.p_lock); 146 147 /* All done! */ 148 if (lp != NULL) { 149 *lp = l; 150 } 151 return 0; 152 } 153 154 /* 155 * Cause a kernel thread to exit. Assumes the exiting thread is the 156 * current context. 157 */ 158 void 159 kthread_exit(int ecode) 160 { 161 const char *name; 162 lwp_t *l = curlwp; 163 164 /* We can't do much with the exit code, so just report it. */ 165 if (ecode != 0) { 166 if ((name = l->l_name) == NULL) 167 name = "unnamed"; 168 printf("WARNING: kthread `%s' (%d) exits with status %d\n", 169 name, l->l_lid, ecode); 170 } 171 172 /* Barrier for joining. */ 173 if (l->l_pflag & LP_MUSTJOIN) { 174 mutex_enter(&kthread_lock); 175 while (kthread_jtarget != l) { 176 cv_wait(&kthread_cv, &kthread_lock); 177 } 178 kthread_jtarget = NULL; 179 cv_broadcast(&kthread_cv); 180 mutex_exit(&kthread_lock); 181 } 182 183 /* And exit.. */ 184 lwp_exit(l); 185 panic("kthread_exit"); 186 } 187 188 /* 189 * Destroy an inactive kthread. The kthread must be in the LSIDL state. 190 */ 191 void 192 kthread_destroy(lwp_t *l) 193 { 194 195 KASSERT((l->l_flag & LW_SYSTEM) != 0); 196 KASSERT(l->l_stat == LSIDL); 197 198 lwp_exit(l); 199 } 200 201 /* 202 * Wait for a kthread to exit, as pthread_join(). 203 */ 204 int 205 kthread_join(lwp_t *l) 206 { 207 208 KASSERT((l->l_flag & LW_SYSTEM) != 0); 209 210 /* 211 * - Wait if some other thread has occupied the target. 212 * - Speicfy our kthread as a target and notify it. 213 * - Wait for the target kthread to notify us. 214 */ 215 mutex_enter(&kthread_lock); 216 while (kthread_jtarget) { 217 cv_wait(&kthread_cv, &kthread_lock); 218 } 219 kthread_jtarget = l; 220 cv_broadcast(&kthread_cv); 221 while (kthread_jtarget == l) { 222 cv_wait(&kthread_cv, &kthread_lock); 223 } 224 mutex_exit(&kthread_lock); 225 226 return 0; 227 } 228