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 /*
  43  * Create a kernel process/thread/whatever.  It shares it's address space
  44  * with proc0 - ie: kernel only.  5.x compatible.
  45  *
  46  * NOTE!  By default kthreads are created with the MP lock held.  A
  47  * thread which does not require the MP lock should release it by calling
  48  * rel_mplock() at the start of the new thread.
  49  */
  50 int
  51 kthread_create(void (*func)(void *), void *arg,
  52     struct thread **tdp, const char *fmt, ...)
  53 {
  54     thread_t td;
  55     __va_list ap;
  56
  57     td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, -1, TDF_VERBOSE);
  58     if (tdp)
  59         *tdp = td;
  60     cpu_set_thread_handler(td, kthread_exit, func, arg);
  61 #ifdef SMP
  62     KKASSERT(td->td_mpcount == 1);
  63 #endif
  64
  65     /*
  66      * Set up arg0 for 'ps' etc
  67      */
  68     __va_start(ap, fmt);
  69     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
  70     __va_end(ap);
  71
  72     /*
  73      * Schedule the thread to run
  74      */
  75     lwkt_schedule(td);
  76     return 0;
  77 }
  78
  79 /*
  80  * Same as kthread_create() but you can specify a custom stack size.
  81  */
  82 int
  83 kthread_create_stk(void (*func)(void *), void *arg,
  84     struct thread **tdp, int stksize, const char *fmt, ...)
  85 {
  86     thread_t td;
  87     __va_list ap;
  88
  89     td = lwkt_alloc_thread(NULL, stksize, -1, TDF_VERBOSE);
  90     if (tdp)
  91         *tdp = td;
  92     cpu_set_thread_handler(td, kthread_exit, func, arg);
  93 #ifdef SMP
  94     KKASSERT(td->td_mpcount == 1);
  95 #endif
  96     __va_start(ap, fmt);
  97     kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
  98     __va_end(ap);
  99
 100     lwkt_schedule(td);
 101     return 0;
 102 }
 103
 104 /*
 105  * Destroy an LWKT thread.   Warning!  This function is not called when
 106  * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
 107  * uses a different reaping mechanism.
 108  *
 109  * XXX duplicates lwkt_exit()
 110  */
 111 void
 112 kthread_exit(void)
 113 {
 114     lwkt_exit();
 115 }
 116
 117
 118 /*
 119  * Start a kernel process.  This is called after a fork() call in
 120  * mi_startup() in the file kern/init_main.c.
 121  *
 122  * This function is used to start "internal" daemons and intended
 123  * to be called from SYSINIT().
 124  */
 125 void
 126 kproc_start(const void *udata)
 127 {
 128         const struct kproc_desc *kp = udata;
 129         int error;
 130
 131         error = kthread_create((void (*)(void *))kp->func, NULL,
 132                     kp->global_threadpp, kp->arg0);
 133         lwkt_setpri(*kp->global_threadpp, TDPRI_KERN_DAEMON);
 134         if (error)
 135                 panic("kproc_start: %s: error %d", kp->arg0, error);
 136 }
 137
 138 /*
 139  * Advise a kernel process to suspend (or resume) in its main loop.
 140  * Participation is voluntary.
 141  */
 142 int
 143 suspend_kproc(struct thread *td, int timo)
 144 {
 145         if (td->td_proc == NULL) {
 146                 td->td_flags |= TDF_STOPREQ;    /* request thread pause */
 147                 wakeup(td);
 148                 while (td->td_flags & TDF_STOPREQ) {
 149                         int error = tsleep(td, 0, "suspkp", timo);
 150                         if (error == EWOULDBLOCK)
 151                                 break;
 152                 }
 153                 td->td_flags &= ~TDF_STOPREQ;
 154                 return(0);
 155         } else {
 156                 return(EINVAL); /* not a kernel thread */
 157         }
 158 }
 159
 160 void
 161 kproc_suspend_loop(void)
 162 {
 163         struct thread *td = curthread;
 164
 165         if (td->td_flags & TDF_STOPREQ) {
 166                 td->td_flags &= ~TDF_STOPREQ;
 167                 while ((td->td_flags & TDF_WAKEREQ) == 0) {
 168                         wakeup(td);
 169                         tsleep(td, 0, "kpsusp", 0);
 170                 }
 171                 td->td_flags &= ~TDF_WAKEREQ;
 172                 wakeup(td);
 173         }
 174 }
 175