| 1 | /* $NetBSD: kern_kthread.c,v 1.41 2015/04/21 11:10:29 pooka 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 1.41 2015/04/21 11:10:29 pooka 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 | (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 | 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 | */ |
| 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_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 | */ |
| 192 | int |
| 193 | kthread_join(lwp_t *l) |
| 194 | { |
| 195 | |
| 196 | KASSERT((l->l_flag & LW_SYSTEM) != 0); |
| 197 | |
| 198 | /* |
| 199 | * - Wait if some other thread has occupied the target. |
| 200 | * - Specify our kthread as a target and notify it. |
| 201 | * - Wait for the target kthread to notify us. |
| 202 | */ |
| 203 | mutex_enter(&kthread_lock); |
| 204 | while (kthread_jtarget) { |
| 205 | cv_wait(&kthread_cv, &kthread_lock); |
| 206 | } |
| 207 | kthread_jtarget = l; |
| 208 | cv_broadcast(&kthread_cv); |
| 209 | while (kthread_jtarget == l) { |
| 210 | cv_wait(&kthread_cv, &kthread_lock); |
| 211 | } |
| 212 | mutex_exit(&kthread_lock); |
| 213 | |
| 214 | return 0; |
| 215 | } |
| 216 | |