FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_kthread.c

     /*      $NetBSD: kern_kthread.c,v 1.24.10.2 2009/02/02 22:02:24 snj Exp $       */
     
     /*-
      * Copyright (c) 1998, 1999, 2007, 2009 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      * NASA Ames Research Center, and by Andrew Doran.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: kern_kthread.c,v 1.24.10.2 2009/02/02 22:02:24 snj Exp $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/kthread.h>
    #include <sys/proc.h>
    #include <sys/sched.h>
    #include <sys/kmem.h>
    
    #include <uvm/uvm_extern.h>
    
    /*
     * note that stdarg.h and the ansi style va_start macro is used for both
     * ansi and traditional c complers.
     * XXX: this requires that stdarg.h define: va_alist and va_dcl
     */
    #include <machine/stdarg.h>
    
    /*
     * Fork a kernel thread.  Any process can request this to be done.
     */
    int
    kthread_create(pri_t pri, int flag, struct cpu_info *ci,
                   void (*func)(void *), void *arg,
                   lwp_t **lp, const char *fmt, ...)
    {
            lwp_t *l;
            vaddr_t uaddr;
            bool inmem;
            int error;
            va_list ap;
            int lc;
    
            inmem = uvm_uarea_alloc(&uaddr);
            if (uaddr == 0)
                    return ENOMEM;
            if ((flag & KTHREAD_TS) != 0) {
                    lc = SCHED_OTHER;
            } else {
                    lc = SCHED_RR;
            }
            error = lwp_create(&lwp0, &proc0, uaddr, inmem, LWP_DETACHED, NULL,
                0, func, arg, &l, lc);
            if (error) {
                    uvm_uarea_free(uaddr, curcpu());
                    return error;
            }
            uvm_lwp_hold(l);
            if (fmt != NULL) {
                    l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP);
                    if (l->l_name == NULL) {
                            lwp_exit(l);
                            return ENOMEM;
                    }
                    va_start(ap, fmt);
                    vsnprintf(l->l_name, MAXCOMLEN, fmt, ap);
                    va_end(ap);
            }
    
            /*
             * Set parameters.
             */
            if ((flag & KTHREAD_INTR) != 0) {
                    KASSERT((flag & KTHREAD_MPSAFE) != 0);
            }
   
           if (pri == PRI_NONE) {
                   if ((flag & KTHREAD_TS) != 0) {
                           /* Maximum user priority level. */
                           pri = MAXPRI_USER;
                   } else {
                           /* Minimum kernel priority level. */
                           pri = PRI_KTHREAD;
                   }
           }
           mutex_enter(proc0.p_lock);
           lwp_lock(l);
           l->l_priority = pri;
           if (ci != NULL) {
                   if (ci != l->l_cpu) {
                           lwp_unlock_to(l, ci->ci_schedstate.spc_mutex);
                           lwp_lock(l);
                   }
                   l->l_pflag |= LP_BOUND;
                   l->l_cpu = ci;
           }
           if ((flag & KTHREAD_INTR) != 0)
                   l->l_pflag |= LP_INTR;
           if ((flag & KTHREAD_MPSAFE) == 0)
                   l->l_pflag &= ~LP_MPSAFE;
   
           /*
            * Set the new LWP running, unless the caller has requested
            * otherwise.
            */
           if ((flag & KTHREAD_IDLE) == 0) {
                   l->l_stat = LSRUN;
                   sched_enqueue(l, false);
                   lwp_unlock(l);
           } else
                   lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock);
   
           /*
            * The LWP is not created suspended or stopped and cannot be set
            * into those states later, so must be considered runnable.
            */
           proc0.p_nrlwps++;
           mutex_exit(proc0.p_lock);
   
           /* All done! */
           if (lp != NULL)
                   *lp = l;
   
           return (0);
   }
   
   /*
    * Cause a kernel thread to exit.  Assumes the exiting thread is the
    * current context.
    */
   void
   kthread_exit(int ecode)
   {
           const char *name;
           lwp_t *l = curlwp;
   
           /* We can't do much with the exit code, so just report it. */
           if (ecode != 0) {
                   if ((name = l->l_name) == NULL)
                           name = "unnamed";
                   printf("WARNING: kthread `%s' (%d) exits with status %d\n",
                       name, l->l_lid, ecode);
           }
   
           /* And exit.. */
           lwp_exit(l);
   
           /*
            * XXX Fool the compiler.  Making exit1() __noreturn__ is a can
            * XXX of worms right now.
            */
           for (;;)
                   ;
   }
   
   /*
    * Destroy an inactive kthread.  The kthread must be in the LSIDL state.
    */
   void
   kthread_destroy(lwp_t *l)
   {
   
           KASSERT((l->l_flag & LW_SYSTEM) != 0);
           KASSERT(l->l_stat == LSIDL);
   
           lwp_exit(l);
   }

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