FreeBSD/Linux Kernel Cross Reference
sys/dev/usbmisc/ugen/ugenbuf.c

     /*
      * Copyright (c) 2004 The DragonFly Project.
      * All rights reserved.
      *
      * This code is derived from software contributed to The DragonFly Project
      * by Matthew Dillon <dillon@backplane.com>.
      *
      * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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
     * COPYRIGHT HOLDERS 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.
     *
     * $DragonFly: src/sys/dev/usbmisc/ugen/ugenbuf.c,v 1.3 2006/09/05 00:55:43 dillon Exp $
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/sysctl.h>
    #include "ugenbuf.h"
    
    static MALLOC_DEFINE(M_UGENBUF, "ugenbufs", "Temporary buffer space");
    static void *ugencache_buf;
    static int ugencache_size;
    
    /*
     * getugenbuf()
     *
     *      Allocate a temporary buffer for UGEN.  This routine is called from
     *      mainline code only and the BGL is held.
     */
    void *
    getugenbuf(int reqsize, int *bsize)
    {
        void *buf;
    
        if (reqsize < 256)
            reqsize = 256;
        if (reqsize > 262144)
            reqsize = 262144;
        *bsize = reqsize;
    
        buf = ugencache_buf;
        if (buf == NULL) {
            buf = kmalloc(reqsize, M_UGENBUF, M_WAITOK);
        } else if (ugencache_size != reqsize) {
            ugencache_buf = NULL;
            kfree(buf, M_UGENBUF);
            buf = kmalloc(reqsize, M_UGENBUF, M_WAITOK);
        } else {
            buf = ugencache_buf;
            ugencache_buf = NULL;
        }
        return(buf);
    }
    
    /*
     * relugenbuf()
     *
     *      Release a temporary buffer for UGEN.  This routine is called from
     *      mainline code only and the BGL is held.
     */
    void
    relugenbuf(void *buf, int bsize)
    {
        if (ugencache_buf == NULL) {
            ugencache_buf = buf;
            ugencache_size = bsize;
        } else {
            kfree(buf, M_UGENBUF);
        }
    }
    

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