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  * $DragonFly: src/sys/kern/kern_kthread.c,v 1.13 2006/12/18 20:41:01 dillon Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/systm.h>
  32 #include <sys/proc.h>
  33 #include <sys/kthread.h>
  34 #include <sys/ptrace.h>
  35 #include <sys/resourcevar.h>
  36 #include <sys/signalvar.h>
  37 #include <sys/unistd.h>
  38 #include <sys/wait.h>
  39
  40 #include <machine/stdarg.h>
  41
  42 static struct lwkt_token kpsus_token = LWKT_TOKEN_INITIALIZER(kpsus_token);
  43
  44
  45 /*
  46  * Create a kernel process/thread/whatever.  It shares it's address space
  47  * with proc0 - ie: kernel only.  5.x compatible.
  48  *
  49  * All kthreads are created as MPSAFE threads.
  50  */
  51 int
  52 kthread_create(void (*func)(void *), void *arg,
  53                struct thread **tdp, const char *fmt, ...)
  54 {
  55     thread_t td;
  56     __va_list ap;
  57
  58     td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, -1, TDF_VERBOSE);
  59     if (tdp)
  60         *tdp = td;
  61     cpu_set_thread_handler(td, kthread_exit, func, arg);
  62
  63     /*
  64      * Set up arg0 for 'ps' etc
  65      */
  66     __va_start(ap, fmt);
  67     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
  68     __va_end(ap);
  69
  70     td->td_ucred = crhold(proc0.p_ucred);
  71
  72     /*
  73      * Schedule the thread to run
  74      */
  75     lwkt_schedule(td);
  76     return 0;
  77 }
  78
  79 int
  80 kthread_create_cpu(void (*func)(void *), void *arg,
  81                    struct thread **tdp, int cpu, const char *fmt, ...)
  82 {
  83     thread_t td;
  84     __va_list ap;
  85
  86     td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, cpu, TDF_VERBOSE);
  87     if (tdp)
  88         *tdp = td;
  89     cpu_set_thread_handler(td, kthread_exit, func, arg);
  90
  91     /*
  92      * Set up arg0 for 'ps' etc
  93      */
  94     __va_start(ap, fmt);
  95     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
  96     __va_end(ap);
  97
  98     td->td_ucred = crhold(proc0.p_ucred);
  99
 100     /*
 101      * Schedule the thread to run
 102      */
 103     lwkt_schedule(td);
 104     return 0;
 105 }
 106
 107 /*
 108  * Same as kthread_create() but you can specify a custom stack size.
 109  */
 110 int
 111 kthread_create_stk(void (*func)(void *), void *arg,
 112                    struct thread **tdp, int stksize, const char *fmt, ...)
 113 {
 114     thread_t td;
 115     __va_list ap;
 116
 117     td = lwkt_alloc_thread(NULL, stksize, -1, TDF_VERBOSE);
 118     if (tdp)
 119         *tdp = td;
 120     cpu_set_thread_handler(td, kthread_exit, func, arg);
 121
 122     __va_start(ap, fmt);
 123     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
 124     __va_end(ap);
 125
 126     lwkt_schedule(td);
 127     return 0;
 128 }
 129
 130 /*
 131  * Destroy an LWKT thread.   Warning!  This function is not called when
 132  * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
 133  * uses a different reaping mechanism.
 134  *
 135  * XXX duplicates lwkt_exit()
 136  */
 137 void
 138 kthread_exit(void)
 139 {
 140     lwkt_exit();
 141 }
 142
 143 /*
 144  * Start a kernel process.  This is called after a fork() call in
 145  * mi_startup() in the file kern/init_main.c.
 146  *
 147  * This function is used to start "internal" daemons and intended
 148  * to be called from SYSINIT().
 149  *
 150  * These threads are created MPSAFE.
 151  */
 152 void
 153 kproc_start(const void *udata)
 154 {
 155         const struct kproc_desc *kp = udata;
 156         int error;
 157
 158         error = kthread_create((void (*)(void *))kp->func, NULL,
 159                                 kp->global_threadpp, kp->arg0);
 160         lwkt_setpri(*kp->global_threadpp, TDPRI_KERN_DAEMON);
 161         if (error)
 162                 panic("kproc_start: %s: error %d", kp->arg0, error);
 163 }
 164
 165 /*
 166  * Advise a kernel process to suspend (or resume) in its main loop.
 167  * Participation is voluntary.
 168  */
 169 int
 170 suspend_kproc(struct thread *td, int timo)
 171 {
 172         if (td->td_proc == NULL) {
 173                 lwkt_gettoken(&kpsus_token);
 174                 td->td_flags |= TDF_STOPREQ;    /* request thread pause */
 175                 wakeup(td);
 176                 while (td->td_flags & TDF_STOPREQ) {
 177                         int error = tsleep(td, 0, "suspkp", timo);
 178                         if (error == EWOULDBLOCK)
 179                                 break;
 180                 }
 181                 td->td_flags &= ~TDF_STOPREQ;
 182                 lwkt_reltoken(&kpsus_token);
 183                 return(0);
 184         } else {
 185                 return(EINVAL); /* not a kernel thread */
 186         }
 187 }
 188
 189 void
 190 kproc_suspend_loop(void)
 191 {
 192         struct thread *td = curthread;
 193
 194         if (td->td_flags & TDF_STOPREQ) {
 195                 lwkt_gettoken(&kpsus_token);
 196                 td->td_flags &= ~TDF_STOPREQ;
 197                 while ((td->td_flags & TDF_WAKEREQ) == 0) {
 198                         wakeup(td);
 199                         tsleep(td, 0, "kpsusp", 0);
 200                 }
 201                 td->td_flags &= ~TDF_WAKEREQ;
 202                 wakeup(td);
 203                 lwkt_reltoken(&kpsus_token);
 204         }
 205 }
 206