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

     /*      $OpenBSD: subr_xxx.c,v 1.17 2019/05/17 03:53:08 visa Exp $      */
     /*      $NetBSD: subr_xxx.c,v 1.10 1996/02/04 02:16:51 christos Exp $   */
     
     /*
      * Copyright (c) 1982, 1986, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * 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. 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.
     *
     *      @(#)subr_xxx.c  8.1 (Berkeley) 6/10/93
     */
    
    /*
     * Miscellaneous trivial functions, including many
     * that are often inline-expanded or done in assembler.
     */
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/conf.h>
    #include <sys/smr.h>
    
    
    /*
     * Unsupported device function (e.g. writing to read-only device).
     */
    int
    enodev(void)
    {
    
            return (ENODEV);
    }
    
    /*
     * Unconfigured device function; driver not configured.
     */
    int
    enxio(void)
    {
    
            return (ENXIO);
    }
    
    /*
     * Unsupported ioctl function.
     */
    int
    enoioctl(void)
    {
    
            return (ENOTTY);
    }
    
    /*
     * Unsupported system function.
     * This is used for an otherwise-reasonable operation
     * that is not supported by the current system binary.
     */
    int
    enosys(void)
    {
    
            return (ENOSYS);
    }
    
    /*
     * Return error for operation not supported
     * on a specific object or file type.
     */
    int
    eopnotsupp(void *v)
    {
    
            return (EOPNOTSUPP);
    }
    
    /*
     * Generic null operation, always returns success.
    */
   int
   nullop(void *v)
   {
   
           return (0);
   }
   
   struct bdevsw *
   bdevsw_lookup(dev_t dev)
   {
           return (&bdevsw[major(dev)]);
   }
   
   struct cdevsw *
   cdevsw_lookup(dev_t dev)
   {
           return (&cdevsw[major(dev)]);
   }
   
   /*
    * Convert a character device number to a block device number.
    */
   dev_t
   chrtoblk(dev_t dev)
   {
           int blkmaj;
   
           if (major(dev) >= nchrdev || major(dev) >= nchrtoblktbl)
                   return (NODEV);
           blkmaj = chrtoblktbl[major(dev)];
           if (blkmaj == NODEV)
                   return (NODEV);
           return (makedev(blkmaj, minor(dev)));
   }
   
   /*
    * Convert a block device number to a character device number.
    */
   dev_t
   blktochr(dev_t dev)
   {
           int blkmaj = major(dev);
           int i;
   
           if (blkmaj >= nblkdev)
                   return (NODEV);
           for (i = 0; i < nchrtoblktbl; i++)
                   if (blkmaj == chrtoblktbl[i])
                           return (makedev(i, minor(dev)));
           return (NODEV);
   }
   
   /*
    * Check that we're in a context where it's okay to sleep.
    */
   void
   assertwaitok(void)
   {
           if (panicstr || db_active)
                   return;
   
           splassert(IPL_NONE);
           SMR_ASSERT_NONCRITICAL();
   #ifdef DIAGNOSTIC
           if (curcpu()->ci_mutex_level != 0)
                   panic("assertwaitok: non-zero mutex count: %d",
                       curcpu()->ci_mutex_level);
   #endif
   }

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