sys/kern/kern_kthread.c

   1 /*
   2  * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/kern/kern_kthread.c,v 1.5.2.3 2001/12/25 01:51:14 dillon Exp $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/proc.h>
  32 #include <sys/kthread.h>
  33 #include <sys/ptrace.h>
  34 #include <sys/resourcevar.h>
  35 #include <sys/signalvar.h>
  36 #include <sys/unistd.h>
  37 #include <sys/wait.h>
  38
  39 #include <machine/stdarg.h>
  40
  41 static struct lwkt_token kpsus_token = LWKT_TOKEN_INITIALIZER(kpsus_token);
  42
  43
  44 /*
  45  * Create a new lightweight kernel thread.
  46  */
  47 static int
  48 _kthread_create(void (*func)(void *), void *arg,
  49     struct thread **tdp, int cpu, const char *fmt, __va_list ap)
  50 {
  51     thread_t td;
  52     int flags = 0;
  53
  54     if (bootverbose)
  55         atomic_set_int(&flags, TDF_VERBOSE);
  56
  57     td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, cpu, flags);
  58     if (tdp)
  59         *tdp = td;
  60     cpu_set_thread_handler(td, kthread_exit, func, arg);
  61
  62     /*
  63      * Set up arg0 for 'ps' etc
  64      */
  65     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
  66
  67     td->td_ucred = crhold(proc0.p_ucred);
  68
  69     /*
  70      * Schedule the thread to run
  71      */
  72     lwkt_schedule(td);
  73
  74     return 0;
  75 }
  76
  77 /*
  78  * Creates a lwkt. No CPU preference.
  79  */
  80 int
  81 kthread_create(void (*func)(void *), void *arg,
  82                struct thread **tdp, const char *fmt, ...)
  83 {
  84         __va_list ap;
  85         int ret;
  86
  87         __va_start(ap, fmt);
  88         ret = _kthread_create(func, arg, tdp, -1, fmt, ap);
  89         __va_end(ap);
  90
  91         return ret;
  92 }
  93
  94 /*
  95  * Creates a lwkt and schedule it to run in a specific CPU.
  96  *
  97  */
  98 int
  99 kthread_create_cpu(void (*func)(void *), void *arg,
 100                    struct thread **tdp, int cpu, const char *fmt, ...)
 101 {
 102         __va_list ap;
 103         int ret;
 104
 105         __va_start(ap, fmt);
 106         ret = _kthread_create(func, arg, tdp, cpu, fmt, ap);
 107         __va_end(ap);
 108
 109         return ret;
 110 }
 111
 112 #if 0
 113 /*
 114  * Same as kthread_create() but you can specify a custom stack size.
 115  */
 116 int
 117 kthread_create_stk(void (*func)(void *), void *arg,
 118                    struct thread **tdp, int stksize, const char *fmt, ...)
 119 {
 120     thread_t td;
 121     __va_list ap;
 122
 123     td = lwkt_alloc_thread(NULL, stksize, -1, TDF_VERBOSE);
 124     if (tdp)
 125         *tdp = td;
 126     cpu_set_thread_handler(td, kthread_exit, func, arg);
 127
 128     __va_start(ap, fmt);
 129     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
 130     __va_end(ap);
 131
 132     lwkt_schedule(td);
 133     return 0;
 134 }
 135 #endif
 136
 137 /*
 138  * Destroy an LWKT thread.   Warning!  This function is not called when
 139  * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
 140  * uses a different reaping mechanism.
 141  *
 142  * XXX duplicates lwkt_exit()
 143  */
 144 void
 145 kthread_exit(void)
 146 {
 147     lwkt_exit();
 148 }
 149
 150 /*
 151  * Start a kernel process.  This is called after a fork() call in
 152  * mi_startup() in the file kern/init_main.c.
 153  *
 154  * This function is used to start "internal" daemons and intended
 155  * to be called from SYSINIT().
 156  *
 157  * These threads are created MPSAFE.
 158  */
 159 void
 160 kproc_start(const void *udata)
 161 {
 162         const struct kproc_desc *kp = udata;
 163         int error;
 164
 165         error = kthread_create((void (*)(void *))kp->func, NULL,
 166                                 kp->global_threadpp, "%s", kp->arg0);
 167         lwkt_setpri(*kp->global_threadpp, TDPRI_KERN_DAEMON);
 168         if (error)
 169                 panic("kproc_start: %s: error %d", kp->arg0, error);
 170 }
 171
 172 /*
 173  * Advise a kernel process to suspend (or resume) in its main loop.
 174  * Participation is voluntary.
 175  */
 176 int
 177 suspend_kproc(struct thread *td, int timo)
 178 {
 179         if (td->td_proc == NULL) {
 180                 lwkt_gettoken(&kpsus_token);
 181                 /* request thread pause */
 182                 atomic_set_int(&td->td_mpflags, TDF_MP_STOPREQ);
 183                 wakeup(td);
 184                 while (td->td_mpflags & TDF_MP_STOPREQ) {
 185                         int error = tsleep(td, 0, "suspkp", timo);
 186                         if (error == EWOULDBLOCK)
 187                                 break;
 188                 }
 189                 atomic_clear_int(&td->td_mpflags, TDF_MP_STOPREQ);
 190                 lwkt_reltoken(&kpsus_token);
 191                 return(0);
 192         } else {
 193                 return(EINVAL); /* not a kernel thread */
 194         }
 195 }
 196
 197 void
 198 kproc_suspend_loop(void)
 199 {
 200         struct thread *td = curthread;
 201
 202         if (td->td_mpflags & TDF_MP_STOPREQ) {
 203                 lwkt_gettoken(&kpsus_token);
 204                 atomic_clear_int(&td->td_mpflags, TDF_MP_STOPREQ);
 205                 while ((td->td_mpflags & TDF_MP_WAKEREQ) == 0) {
 206                         wakeup(td);
 207                         tsleep(td, 0, "kpsusp", 0);
 208                 }
 209                 atomic_clear_int(&td->td_mpflags, TDF_MP_WAKEREQ);
 210                 wakeup(td);
 211                 lwkt_reltoken(&kpsus_token);
 212         }
 213 }
 214