sys/kern/kern_kthread.c

   1 /*      $NetBSD: kern_kthread.c,v 1.26 2009/01/30 04:09:35 agc 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 1.26 2009/01/30 04:09:35 agc 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/proc.h>
  41 #include <sys/sched.h>
  42 #include <sys/kmem.h>
  43
  44 #include <uvm/uvm_extern.h>
  45
  46 /*
  47  * note that stdarg.h and the ansi style va_start macro is used for both
  48  * ansi and traditional c complers.
  49  * XXX: this requires that stdarg.h define: va_alist and va_dcl
  50  */
  51 #include <machine/stdarg.h>
  52
  53 /*
  54  * Fork a kernel thread.  Any process can request this to be done.
  55  */
  56 int
  57 kthread_create(pri_t pri, int flag, struct cpu_info *ci,
  58                void (*func)(void *), void *arg,
  59                lwp_t **lp, const char *fmt, ...)
  60 {
  61         lwp_t *l;
  62         vaddr_t uaddr;
  63         int error;
  64         va_list ap;
  65         int lc;
  66
  67         uaddr = uvm_uarea_alloc();
  68         if (uaddr == 0) {
  69                 return ENOMEM;
  70         }
  71         if ((flag & KTHREAD_TS) != 0) {
  72                 lc = SCHED_OTHER;
  73         } else {
  74                 lc = SCHED_RR;
  75         }
  76         error = lwp_create(&lwp0, &proc0, uaddr, LWP_DETACHED, NULL,
  77             0, func, arg, &l, lc);
  78         if (error) {
  79                 uvm_uarea_free(uaddr);
  80                 return error;
  81         }
  82         if (fmt != NULL) {
  83                 l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP);
  84                 if (l->l_name == NULL) {
  85                         lwp_exit(l);
  86                         return ENOMEM;
  87                 }
  88                 va_start(ap, fmt);
  89                 vsnprintf(l->l_name, MAXCOMLEN, fmt, ap);
  90                 va_end(ap);
  91         }
  92
  93         /*
  94          * Set parameters.
  95          */
  96         if ((flag & KTHREAD_INTR) != 0) {
  97                 KASSERT((flag & KTHREAD_MPSAFE) != 0);
  98         }
  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         if ((flag & KTHREAD_INTR) != 0)
 121                 l->l_pflag |= LP_INTR;
 122         if ((flag & KTHREAD_MPSAFE) == 0)
 123                 l->l_pflag &= ~LP_MPSAFE;
 124
 125         /*
 126          * Set the new LWP running, unless the caller has requested
 127          * otherwise.
 128          */
 129         if ((flag & KTHREAD_IDLE) == 0) {
 130                 l->l_stat = LSRUN;
 131                 sched_enqueue(l, false);
 132                 lwp_unlock(l);
 133         } else
 134                 lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock);
 135
 136         /*
 137          * The LWP is not created suspended or stopped and cannot be set
 138          * into those states later, so must be considered runnable.
 139          */
 140         proc0.p_nrlwps++;
 141         mutex_exit(proc0.p_lock);
 142
 143         /* All done! */
 144         if (lp != NULL)
 145                 *lp = l;
 146
 147         return (0);
 148 }
 149
 150 /*
 151  * Cause a kernel thread to exit.  Assumes the exiting thread is the
 152  * current context.
 153  */
 154 void
 155 kthread_exit(int ecode)
 156 {
 157         const char *name;
 158         lwp_t *l = curlwp;
 159
 160         /* We can't do much with the exit code, so just report it. */
 161         if (ecode != 0) {
 162                 if ((name = l->l_name) == NULL)
 163                         name = "unnamed";
 164                 printf("WARNING: kthread `%s' (%d) exits with status %d\n",
 165                     name, l->l_lid, ecode);
 166         }
 167
 168         /* And exit.. */
 169         lwp_exit(l);
 170
 171         /*
 172          * XXX Fool the compiler.  Making exit1() __noreturn__ is a can
 173          * XXX of worms right now.
 174          */
 175         for (;;)
 176                 ;
 177 }
 178
 179 /*
 180  * Destroy an inactive kthread.  The kthread must be in the LSIDL state.
 181  */
 182 void
 183 kthread_destroy(lwp_t *l)
 184 {
 185
 186         KASSERT((l->l_flag & LW_SYSTEM) != 0);
 187         KASSERT(l->l_stat == LSIDL);
 188
 189         lwp_exit(l);
 190 }