FreeBSD/Linux Kernel Cross Reference
sys/net/route/nhop_utils.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2020 Alexander V. Chernikov
      *
      * 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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    #include "opt_inet.h"
    #include "opt_route.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/kernel.h>
    
    #include <net/route/nhop_utils.h>
    
    #define BLOCK_ITEMS     (8 * sizeof(u_long))    /* Number of items for ffsl() */
    
    #define _BLOCKS_TO_SZ(_blocks)          ((size_t)(_blocks) * sizeof(u_long))
    #define _BLOCKS_TO_ITEMS(_blocks)       ((uint32_t)(_blocks) * BLOCK_ITEMS)
    #define _ITEMS_TO_BLOCKS(_items)        ((_items) / BLOCK_ITEMS)
    
    static void _bitmask_init_idx(void *index, uint32_t items);
    
    void
    bitmask_init(struct bitmask_head *bh, void *idx, uint32_t num_items)
    {
    
            if (idx != NULL)
                    _bitmask_init_idx(idx, num_items);
    
            memset(bh, 0, sizeof(struct bitmask_head));
            bh->blocks = _ITEMS_TO_BLOCKS(num_items);
            bh->idx = (u_long *)idx;
    }
    
    uint32_t
    bitmask_get_resize_items(const struct bitmask_head *bh)
    {
            if ((bh->items_count * 2 > _BLOCKS_TO_ITEMS(bh->blocks)) && bh->items_count < 65536)
                    return (_BLOCKS_TO_ITEMS(bh->blocks) * 2);
    
            return (0);
    }
    
    int
    bitmask_should_resize(const struct bitmask_head *bh)
    {
    
            return (bitmask_get_resize_items(bh) != 0);
    }
    
    #if 0
    uint32_t
    _bitmask_get_blocks(uint32_t items)
    {
    
            return (items / BLOCK_ITEMS);
    }
    #endif
    
    size_t
    bitmask_get_size(uint32_t items)
    {
    #if _KERNEL
            KASSERT((items % BLOCK_ITEMS) == 0,
               ("bitmask size needs to power of 2 and greater or equal to %zu",
                BLOCK_ITEMS));
    #else
            assert((items % BLOCK_ITEMS) == 0);
    #endif
    
            return (items / 8);
    }
   
   static void
   _bitmask_init_idx(void *_idx, uint32_t items)
   {
           size_t size = bitmask_get_size(items);
           u_long *idx = (u_long *)_idx;
   
           /* Mark all as free */
           memset(idx, 0xFF, size);
           *idx &= ~(u_long)1; /* Always skip index 0 */
   }
   
   /*
    * _try_merge api to allow shrinking?
    */
   int
   bitmask_copy(const struct bitmask_head *bi, void *new_idx, uint32_t new_items)
   {
           uint32_t new_blocks = _BLOCKS_TO_ITEMS(new_items);
   
           _bitmask_init_idx(new_idx, new_items);
   
           if (bi->blocks < new_blocks) {
                   /* extend current blocks */
                   if (bi->blocks > 0)
                           memcpy(new_idx, bi->idx, _BLOCKS_TO_SZ(bi->blocks));
                   return (0);
           } else {
                   /* XXX: ensure all other blocks are non-zero */
                   for (int i = new_blocks; i < bi->blocks; i++) {
                   }
   
                   return (1);
           }
   }
   
   void
   bitmask_swap(struct bitmask_head *bh, void *new_idx, uint32_t new_items, void **pidx)
   {
           void *old_ptr;
   
           old_ptr = bh->idx;
   
           bh->idx = (u_long *)new_idx;
           bh->blocks = _ITEMS_TO_BLOCKS(new_items);
   
           if (pidx != NULL)
                   *pidx = old_ptr;
   }
   
   /*
    * Allocate new index in given instance and stores in in @pidx.
    * Returns 0 on success.
    */
   int
   bitmask_alloc_idx(struct bitmask_head *bi, uint16_t *pidx)
   {
           u_long *mask;
           int i, off, v;
   
           off = bi->free_off;
           mask = &bi->idx[off];
   
           for (i = off; i < bi->blocks; i++, mask++) {
                   if ((v = ffsl(*mask)) == 0)
                           continue;
   
                   /* Mark as busy */
                   *mask &= ~ ((u_long)1 << (v - 1));
   
                   bi->free_off = i;
   
                   v = BLOCK_ITEMS * i + v - 1;
   
                   *pidx = v;
                   bi->items_count++;
                   return (0);
           }
   
           return (1);
   }
   
   /*
    * Removes index from given set.
    * Returns 0 on success.
    */
   int
   bitmask_free_idx(struct bitmask_head *bi, uint16_t idx)
   {
           u_long *mask;
           int i, v;
   
           if (idx == 0)
                   return (1);
   
           i = idx / BLOCK_ITEMS;
           v = idx % BLOCK_ITEMS;
   
           if (i >= bi->blocks)
                   return (1);
   
           mask = &bi->idx[i];
   
           if ((*mask & ((u_long)1 << v)) != 0)
                   return (1);
   
           /* Mark as free */
           *mask |= (u_long)1 << v;
           bi->items_count--;
   
           /* Update free offset */
           if (bi->free_off > i)
                   bi->free_off = i;
   
           return (0);
   }

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