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

     /*
      *
      * Portions of this code was derived from the file kern_fork.c and as such
      * is subject to the copyrights below.
      *
      * Copyright (c) 1982, 1986, 1989, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
     * to the University of California by American Telephone and Telegraph
     * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * 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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
     *
     * Copyright (c) 1996 Douglas Santry
     *
     * This code is subject to the beer copyright.  If I chance to meet you in a
     * bar and this code helped you in some way, you owe me a beer.  Only
     * in Germany will I accept domestic beer.  This code may or may not work
     * and I certainly make no claims as to its fitness for *any* purpose.
     * 
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/proc.h>
    #include <sys/sysproto.h>
    
    /*
     * Low level support for sleep/wakeup paradigm
     * If a timeout is specified:
     *      returns 0 if wakeup
     *      returns EAGAIN if timed out
     *      returns EINVAL if error
     *
     * If a timeout is not specified:
     *
     *      returns time waiting in ticks.
     */
    int
    thr_sleep(struct proc *p, struct thr_sleep_args *uap) {
            int sleepstart;
            struct timespec ts;
            struct timeval atv;
            int error, timo;
    
            timo = 0;
            if (uap->timeout != 0) {
                    /*
                     * Get timespec struct
                     */
                    if (error = copyin((caddr_t) uap->timeout, (caddr_t) &ts, sizeof ts)) {
                            p->p_wakeup = 0;
                            return error;
                    }
                    if (ts.tv_nsec < 0 || ts.tv_nsec >= 1000000000) {
                            p->p_wakeup = 0;
                            return (EINVAL);
                    }
                    TIMESPEC_TO_TIMEVAL(&atv, &ts);
                    if (itimerfix(&atv)) {
                            p->p_wakeup = 0;
                            return (EINVAL);
                    }
                    timo = tvtohz(&atv);
            }
    
            p->p_retval[0] = 0;
            if (p->p_wakeup == 0) {
                    sleepstart = ticks;
                   p->p_flag |= P_SINTR;
                   error = tsleep(p, PRIBIO, "thrslp", timo);
                   p->p_flag &= ~P_SINTR;
                   if (error == EWOULDBLOCK) {
                           p->p_wakeup = 0;
                           p->p_retval[0] = EAGAIN;
                           return 0;
                   }
                   if (uap->timeout == 0)
                           p->p_retval[0] = ticks - sleepstart;
           }
           p->p_wakeup = 0;
           return (0);
   }
   
   int
   thr_wakeup(struct proc *p, struct thr_wakeup_args *uap) {
           struct proc *pSlave = p->p_leader;
   
           while(pSlave && (pSlave->p_pid != uap->pid))
                   pSlave = pSlave->p_peers;
   
           if(pSlave == 0) {
                   p->p_retval[0] = ESRCH;
                   return(0);
           }
   
           pSlave->p_wakeup++;
           if((pSlave->p_stat == SSLEEP) && (pSlave->p_wchan == pSlave)) {
                   wakeup(pSlave);
                   return(0);
           }
   
           p->p_retval[0] = EAGAIN;
           return 0;
   }
   
   /*
    * General purpose yield system call
    */
   int
   yield(struct proc *p, struct yield_args *uap) {
           int s;
   
           p->p_retval[0] = 0;
   
           s = splhigh();
           p->p_priority = MAXPRI;
           setrunqueue(p);
           mi_switch();
           splx(s);
   
           return(0);
   }
   

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