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

     /*
      * Copyright (c) 1998 David Greenman.  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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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/kern/kern_sfbuf.c,v 1.15 2007/04/30 07:18:53 dillon Exp $
     */
    
    #include <sys/param.h>
    #include <sys/types.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/sfbuf.h>
    #include <sys/refcount.h>
    #include <sys/objcache.h>
    
    #include <cpu/lwbuf.h>
    
    #include <vm/vm.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_page.h>
    #include <vm/pmap.h>
    
    static void sf_buf_init(void *arg);
    SYSINIT(sock_sf, SI_BOOT2_MACHDEP, SI_ORDER_ANY, sf_buf_init, NULL)
    
    LIST_HEAD(sf_buf_list, sf_buf);
    
    static struct objcache *sf_buf_cache;
    
    MALLOC_DEFINE(M_SFBUF, "sfbuf", "Sendfile buffer structures");
    struct objcache_malloc_args sf_buf_malloc_args = { sizeof(struct sf_buf), M_SFBUF };
    
    
    static boolean_t
    sf_buf_cache_ctor(void *obj, void *pdata, int ocflags)
    {
            struct sf_buf *sf = (struct sf_buf *)obj;
    
            sf->lwbuf = NULL;
            refcount_init(&sf->ref, 0);
    
            return (TRUE);
    }
    
    /*
     * Init objcache of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
     */
    static void
    sf_buf_init(void *arg)
    {
            sf_buf_cache = objcache_create("sf_buf", 0, 0,
                    sf_buf_cache_ctor, NULL, NULL,
                    objcache_malloc_alloc, objcache_malloc_free,
                    &sf_buf_malloc_args);
    }
    
    /*
     * Acquire an sf_buf reference for a vm_page.
     */
    struct sf_buf *
    sf_buf_alloc(struct vm_page *m)
    {
            struct sf_buf *sf;
    
            if ((sf = objcache_get(sf_buf_cache, M_WAITOK)) == NULL)
                    goto done;
    
            if ((sf->lwbuf = lwbuf_alloc(m, &sf->lwbuf_cache)) == NULL) {
                    objcache_put(sf_buf_cache, sf);
                    sf = NULL;
                    goto done;
            }
    
            /*
             * Force invalidation of the TLB entry on all CPU's
             */
            lwbuf_set_global(sf->lwbuf);
   
           refcount_init(&sf->ref, 1);
   
   done:
           return (sf);
   }
   
   void
   sf_buf_ref(void *arg)
   {
           struct sf_buf *sf = arg;
   
           refcount_acquire(&sf->ref);
   }
   
   /*
    * Detach mapped page and release resources back to the system.
    *
    * Returns non-zero (TRUE) if this was the last release of the sfbuf.
    *
    * (matching the same API that refcount_release() uses to reduce confusion)
    */
   int
   sf_buf_free(void *arg)
   {
           struct sf_buf *sf = arg;
   
           if (refcount_release(&sf->ref)) {
                   lwbuf_free(sf->lwbuf);
                   objcache_put(sf_buf_cache, sf);
                   return (1);
           }
           return (0);
   }

Cache object: ddf1b6bf2e15442e3537ffd505786469