kern_kthread.c revision 1.43
1/* $NetBSD: kern_kthread.c,v 1.43 2018/01/09 22:58:45 pgoyette 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 1.43 2018/01/09 22:58:45 pgoyette 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, &lwp0.l_sigmask, &lwp0.l_sigstk); 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 va_start(ap, fmt); 93 vsnprintf(l->l_name, MAXCOMLEN, fmt, ap); 94 va_end(ap); 95 } 96 97 /* 98 * Set parameters. 99 */ 100 if (pri == PRI_NONE) { 101 if ((flag & KTHREAD_TS) != 0) { 102 /* Maximum user priority level. */ 103 pri = MAXPRI_USER; 104 } else { 105 /* Minimum kernel priority level. */ 106 pri = PRI_KTHREAD; 107 } 108 } 109 mutex_enter(proc0.p_lock); 110 lwp_lock(l); 111 l->l_priority = pri; 112 if (ci != NULL) { 113 if (ci != l->l_cpu) { 114 lwp_unlock_to(l, ci->ci_schedstate.spc_mutex); 115 lwp_lock(l); 116 } 117 l->l_pflag |= LP_BOUND; 118 l->l_cpu = ci; 119 } 120 121 if ((flag & KTHREAD_MUSTJOIN) != 0) { 122 KASSERT(lp != NULL); 123 l->l_pflag |= LP_MUSTJOIN; 124 } 125 if ((flag & KTHREAD_INTR) != 0) { 126 l->l_pflag |= LP_INTR; 127 } 128 if ((flag & KTHREAD_MPSAFE) == 0) { 129 l->l_pflag &= ~LP_MPSAFE; 130 } 131 132 /* 133 * Set the new LWP running, unless the caller has requested 134 * otherwise. 135 */ 136 if ((flag & KTHREAD_IDLE) == 0) { 137 l->l_stat = LSRUN; 138 sched_enqueue(l, false); 139 lwp_unlock(l); 140 } else { 141 if (ci != NULL) 142 lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock); 143 else 144 lwp_unlock(l); 145 } 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 */ 159void 160kthread_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_MUSTJOIN) { 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 * Wait for a kthread to exit, as pthread_join(). 191 */ 192int 193kthread_join(lwp_t *l) 194{ 195 196 KASSERT((l->l_flag & LW_SYSTEM) != 0); 197 KASSERT((l->l_pflag & LP_MUSTJOIN) != 0); 198 199 /* 200 * - Wait if some other thread has occupied the target. 201 * - Specify our kthread as a target and notify it. 202 * - Wait for the target kthread to notify us. 203 */ 204 mutex_enter(&kthread_lock); 205 while (kthread_jtarget) { 206 cv_wait(&kthread_cv, &kthread_lock); 207 } 208 kthread_jtarget = l; 209 cv_broadcast(&kthread_cv); 210 while (kthread_jtarget == l) { 211 cv_wait(&kthread_cv, &kthread_lock); 212 } 213 mutex_exit(&kthread_lock); 214 215 return 0; 216} 217