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     td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, cpu, flags);
  55     if (tdp)
  56         *tdp = td;
  57     cpu_set_thread_handler(td, kthread_exit, func, arg);
  58
  59     /*
  60      * Set up arg0 for 'ps' etc
  61      */
  62     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
  63
  64     td->td_ucred = crhold(proc0.p_ucred);
  65
  66     /*
  67      * Schedule the thread to run
  68      */
  69     lwkt_schedule(td);
  70
  71     return 0;
  72 }
  73
  74 /*
  75  * Creates a lwkt. No CPU preference.
  76  */
  77 int
  78 kthread_create(void (*func)(void *), void *arg,
  79                struct thread **tdp, const char *fmt, ...)
  80 {
  81         __va_list ap;
  82         int ret;
  83
  84         __va_start(ap, fmt);
  85         ret = _kthread_create(func, arg, tdp, -1, fmt, ap);
  86         __va_end(ap);
  87
  88         return ret;
  89 }
  90
  91 /*
  92  * Creates a lwkt and schedule it to run in a specific CPU.
  93  *
  94  */
  95 int
  96 kthread_create_cpu(void (*func)(void *), void *arg,
  97                    struct thread **tdp, int cpu, const char *fmt, ...)
  98 {
  99         __va_list ap;
 100         int ret;
 101
 102         __va_start(ap, fmt);
 103         ret = _kthread_create(func, arg, tdp, cpu, fmt, ap);
 104         __va_end(ap);
 105
 106         return ret;
 107 }
 108
 109 #if 0
 110 /*
 111  * Same as kthread_create() but you can specify a custom stack size.
 112  */
 113 int
 114 kthread_create_stk(void (*func)(void *), void *arg,
 115                    struct thread **tdp, int stksize, const char *fmt, ...)
 116 {
 117     thread_t td;
 118     __va_list ap;
 119
 120     td = lwkt_alloc_thread(NULL, stksize, -1, 0);
 121     if (tdp)
 122         *tdp = td;
 123     cpu_set_thread_handler(td, kthread_exit, func, arg);
 124
 125     __va_start(ap, fmt);
 126     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
 127     __va_end(ap);
 128
 129     lwkt_schedule(td);
 130     return 0;
 131 }
 132 #endif
 133
 134 /*
 135  * Destroy an LWKT thread.   Warning!  This function is not called when
 136  * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
 137  * uses a different reaping mechanism.
 138  *
 139  * XXX duplicates lwkt_exit()
 140  */
 141 void
 142 kthread_exit(void)
 143 {
 144     lwkt_exit();
 145 }
 146
 147 /*
 148  * Start a kernel process.  This is called after a fork() call in
 149  * mi_startup() in the file kern/init_main.c.
 150  *
 151  * This function is used to start "internal" daemons and intended
 152  * to be called from SYSINIT().
 153  *
 154  * These threads are created MPSAFE.
 155  */
 156 void
 157 kproc_start(const void *udata)
 158 {
 159         const struct kproc_desc *kp = udata;
 160         int error;
 161
 162         error = kthread_create((void (*)(void *))kp->func, NULL,
 163                                 kp->global_threadpp, "%s", kp->arg0);
 164         lwkt_setpri(*kp->global_threadpp, TDPRI_KERN_DAEMON);
 165         if (error)
 166                 panic("kproc_start: %s: error %d", kp->arg0, error);
 167 }
 168
 169 /*
 170  * Advise a kernel process to suspend (or resume) in its main loop.
 171  * Participation is voluntary.
 172  */
 173 int
 174 suspend_kproc(struct thread *td, int timo)
 175 {
 176         if (td->td_proc == NULL) {
 177                 lwkt_gettoken(&kpsus_token);
 178                 /* request thread pause */
 179                 atomic_set_int(&td->td_mpflags, TDF_MP_STOPREQ);
 180                 wakeup(td);
 181                 while (td->td_mpflags & TDF_MP_STOPREQ) {
 182                         int error = tsleep(td, 0, "suspkp", timo);
 183                         if (error == EWOULDBLOCK)
 184                                 break;
 185                 }
 186                 atomic_clear_int(&td->td_mpflags, TDF_MP_STOPREQ);
 187                 lwkt_reltoken(&kpsus_token);
 188                 return(0);
 189         } else {
 190                 return(EINVAL); /* not a kernel thread */
 191         }
 192 }
 193
 194 void
 195 kproc_suspend_loop(void)
 196 {
 197         struct thread *td = curthread;
 198
 199         if (td->td_mpflags & TDF_MP_STOPREQ) {
 200                 lwkt_gettoken(&kpsus_token);
 201                 atomic_clear_int(&td->td_mpflags, TDF_MP_STOPREQ);
 202                 while ((td->td_mpflags & TDF_MP_WAKEREQ) == 0) {
 203                         wakeup(td);
 204                         tsleep(td, 0, "kpsusp", 0);
 205                 }
 206                 atomic_clear_int(&td->td_mpflags, TDF_MP_WAKEREQ);
 207                 wakeup(td);
 208                 lwkt_reltoken(&kpsus_token);
 209         }
 210 }
 211