484 lines
13 KiB
C
484 lines
13 KiB
C
/*
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* Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com>
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* Copyright (c) 2011 Jeffrey Roberson <jeff@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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/*
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* Radix tree implementation.
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*/
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#include <sys/cdefs.h>
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#include <sys/param.h>
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#include <sys/conf.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/queue.h>
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#include <sys/param.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/ktr.h>
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#include <vm/vm.h>
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#include <vm/vm_radix.h>
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#include <vm/vm_object.h>
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#include <sys/kdb.h>
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SLIST_HEAD(, vm_radix_node) res_rnodes_head =
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SLIST_HEAD_INITIALIZER(res_rnodes_head);
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struct mtx rnode_lock;
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vm_offset_t rnode_start;
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vm_offset_t rnode_end;
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/*
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* Allocate a radix node. Initializes all elements to 0.
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*/
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static struct vm_radix_node *
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vm_radix_node_get(void)
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{
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struct vm_radix_node *rnode;
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if (VM_OBJECT_LOCKED(kernel_object) || VM_OBJECT_LOCKED(kmem_object)){
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mtx_lock_spin(&rnode_lock);
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if (!SLIST_EMPTY(&res_rnodes_head)) {
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rnode = SLIST_FIRST(&res_rnodes_head);
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SLIST_REMOVE_HEAD(&res_rnodes_head, next);
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mtx_unlock_spin(&rnode_lock);
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bzero((void *)rnode, sizeof(*rnode));
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goto out;
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}
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mtx_unlock_spin(&rnode_lock);
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panic("No memory for kernel_object. . .");
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}
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rnode = malloc(sizeof(struct vm_radix_node), M_TEMP, M_NOWAIT | M_ZERO);
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if (rnode == NULL) {
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panic("vm_radix_node_get: Can not allocate memory\n");
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return NULL;
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}
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out:
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return rnode;
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}
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/*
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* Free radix node.
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*/
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static void
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vm_radix_node_put(struct vm_radix_node *rnode)
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{
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KASSERT(rnode->rn_count == 0,
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("vm_radix_node_put: Freeing a node with %d children\n",
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rnode->rn_count));
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if ((vm_offset_t)rnode >= rnode_start &&
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(vm_offset_t)rnode < rnode_end) {
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mtx_lock_spin(&rnode_lock);
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SLIST_INSERT_HEAD(&res_rnodes_head, rnode, next);
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mtx_unlock_spin(&rnode_lock);
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} else
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free(rnode,M_TEMP);
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}
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/*
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* Return the position in the array for a given level.
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*/
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static inline int
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vm_radix_slot(vm_pindex_t index, int level)
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{
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return ((index >> (level * VM_RADIX_WIDTH)) & VM_RADIX_MASK);
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}
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/*
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* Inserts the key-value pair in to the radix tree. Returns errno.
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* Panics if the key already exists.
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*/
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int
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vm_radix_insert(struct vm_radix *rtree, vm_pindex_t index, void *val)
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{
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struct vm_radix_node *rnode;
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int slot;
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int level;
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CTR3(KTR_VM,
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"insert: tree %p, index %p, val %p", rtree, (void *)index, val);
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if (index == -1)
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panic("vm_radix_insert: -1 is not a valid index.\n");
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/*
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* Increase the height by adding nodes at the root until
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* there is sufficient space.
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*/
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while (rtree->rt_height == 0 ||
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index > VM_RADIX_MAX(rtree->rt_height)) {
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CTR3(KTR_VM, "insert: expanding %jd > %jd height %d",
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index, VM_RADIX_MAX(rtree->rt_height), rtree->rt_height);
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/*
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* Only allocate tree nodes if they are needed.
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*/
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if (rtree->rt_root == NULL || rtree->rt_root->rn_count != 0) {
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rnode = vm_radix_node_get();
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if (rnode == NULL)
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return (ENOMEM);
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if (rtree->rt_root) {
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rnode->rn_child[0] = rtree->rt_root;
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rnode->rn_count = 1;
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}
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rtree->rt_root = rnode;
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}
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rtree->rt_height++;
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KASSERT(rtree->rt_height <= VM_RADIX_LIMIT,
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("vm_radix_insert: Tree %p height %d too tall", rtree,
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rtree->rt_height));
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}
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/* Now that the tree is tall enough, fill in the path to the index. */
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rnode = rtree->rt_root;
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for (level = rtree->rt_height - 1; level > 0; level--) {
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slot = vm_radix_slot(index, level);
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/* Add the required intermidiate nodes. */
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if (rnode->rn_child[slot] == NULL) {
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rnode->rn_child[slot] = vm_radix_node_get();
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if (rnode->rn_child[slot] == NULL)
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return (ENOMEM);
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rnode->rn_count++;
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}
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CTR5(KTR_VM,
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"insert: tree %p, index %p, level %d, slot %d, child %p",
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rtree, (void *)index, level, slot, rnode->rn_child[slot]);
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rnode = rnode->rn_child[slot];
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}
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slot = vm_radix_slot(index, level);
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CTR5(KTR_VM, "insert: tree %p, index %p, level %d, slot %d, child %p",
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rtree, (void *)index, level, slot, rnode->rn_child[slot]);
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KASSERT(rnode->rn_child[slot] == NULL,
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("vm_radix_insert: Duplicate value %p at index: %lu\n",
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rnode->rn_child[slot], (u_long)index));
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rnode->rn_child[slot] = val;
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rnode->rn_count++;
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return 0;
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}
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/*
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* Returns the value stored at the index. If the index is not present
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* NULL is returned.
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*/
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void *
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vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index)
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{
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struct vm_radix_node *rnode;
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int slot;
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int level;
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if (index > VM_RADIX_MAX(rtree->rt_height))
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return NULL;
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level = rtree->rt_height - 1;
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rnode = rtree->rt_root;
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while (rnode) {
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slot = vm_radix_slot(index, level);
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CTR5(KTR_VM,
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"lookup: tree %p, index %p, level %d, slot %d, child %p",
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rtree, (void *)index, level, slot, rnode->rn_child[slot]);
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if (level == 0)
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return rnode->rn_child[slot];
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rnode = rnode->rn_child[slot];
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level--;
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}
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CTR2(KTR_VM, "lookup: tree %p, index %p failed", rtree, (void *)index);
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return NULL;
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}
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/*
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* Looks up as many as cnt values between start and end inclusive, and stores
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* them in the caller allocated array out. The next index can be used to
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* restart the scan. This optimizes forward scans in the tree.
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*/
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int
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vm_radix_lookupn(struct vm_radix *rtree, vm_pindex_t start,
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vm_pindex_t end, void **out, int cnt, vm_pindex_t *next)
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{
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struct vm_radix_node *rnode;
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struct vm_radix_node *child;
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vm_pindex_t max;
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vm_pindex_t inc;
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int slot;
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int level;
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void *val;
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int outidx;
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int loops = 0;
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CTR3(KTR_VM, "lookupn: tree %p, start %p, end %p",
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rtree, (void *)start, (void *)end);
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outidx = 0;
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max = VM_RADIX_MAX(rtree->rt_height);
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if (start > max)
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return 0;
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if (end > max || end == 0)
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end = max;
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restart:
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loops++;
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if (loops > 1000)
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panic("vm_radix_lookupn: looping %d\n", loops);
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/*
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* Search the tree from the top for any leaf node holding an index
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* between start and end.
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*/
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level = rtree->rt_height - 1;
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rnode = rtree->rt_root;
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while (rnode) {
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slot = vm_radix_slot(start, level);
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CTR5(KTR_VM,
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"lookupn: tree %p, index %p, level %d, slot %d, child %p",
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rtree, (void *)start, level, slot, rnode->rn_child[slot]);
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if (level == 0)
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break;
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/*
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* If we don't have an exact match we must start our search
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* from the next leaf and adjust our index appropriately.
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*/
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if ((child = rnode->rn_child[slot]) == NULL) {
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/*
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* Calculate how much to increment our index by
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* based on the tree level. We must truncate the
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* lower bits to start from the begnning of the next
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* leaf.
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*/
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inc = 1LL << (level * VM_RADIX_WIDTH);
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start &= ~VM_RADIX_MAX(level);
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start += inc;
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slot++;
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CTR5(KTR_VM,
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"lookupn: start %p end %p inc %d mask 0x%lX slot %d",
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(void *)start, (void *)end, inc, ~VM_RADIX_MAX(level), slot);
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for (; slot < VM_RADIX_COUNT && start <= end;
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slot++, start += inc) {
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child = rnode->rn_child[slot];
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if (child)
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break;
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}
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}
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rnode = child;
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level--;
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}
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if (rnode == NULL) {
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/*
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* If we still have another range to search, start looking
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* from the next node. Otherwise, return what we've already
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* found. The loop above has already adjusted start to the
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* beginning of the next node.
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*
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* Detect start wrapping back to 0 and return in this case.
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*/
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if (start <= end && start != 0)
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goto restart;
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goto out;
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}
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for (; outidx < cnt && slot < VM_RADIX_COUNT && start <= end;
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slot++, start++) {
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val = rnode->rn_child[slot];
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if (val == NULL)
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continue;
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out[outidx++] = val;
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}
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/*
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* Go fetch the next page to fill the requested number of pages
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* otherwise the caller will simply call us again to fulfill the
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* same request after the structures are pushed out of cache.
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*/
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if (outidx < cnt && start <= end)
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goto restart;
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out:
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*next = start;
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return (outidx);
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}
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/*
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* Look up any entry at a position less than or equal to index.
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*/
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void *
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vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
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{
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struct vm_radix_node *rnode;
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struct vm_radix_node *child;
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vm_pindex_t max;
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vm_pindex_t inc;
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int slot;
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int level;
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int loops = 0;
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CTR2(KTR_VM,
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"lookup_le: tree %p, index %p", rtree, (void *)index);
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if (rtree->rt_root == NULL)
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return (NULL);
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max = VM_RADIX_MAX(rtree->rt_height);
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if (index > max || index == 0)
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index = max;
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restart:
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loops++;
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if (loops > 1000)
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panic("vm_radix_looku_le: looping %d\n", loops);
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/*
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* Search the tree from the top for any leaf node holding an index
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* lower than 'index'.
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*/
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level = rtree->rt_height - 1;
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rnode = rtree->rt_root;
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while (rnode) {
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slot = vm_radix_slot(index, level);
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CTR5(KTR_VM,
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"lookup_le: tree %p, index %p, level %d, slot %d, child %p",
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rtree, (void *)index, level, slot, rnode->rn_child[slot]);
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if (level == 0)
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break;
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/*
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* If we don't have an exact match we must start our search
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* from the next leaf and adjust our index appropriately.
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*/
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if ((child = rnode->rn_child[slot]) == NULL) {
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/*
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* Calculate how much to decrement our index by
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* based on the tree level. We must set the
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* lower bits to start from the end of the next
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* leaf.
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*/
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inc = 1LL << (level * VM_RADIX_WIDTH);
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index |= VM_RADIX_MAX(level);
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index -= inc;
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slot--;
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CTR4(KTR_VM,
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"lookup_le: start %p inc %ld mask 0x%lX slot %d",
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(void *)index, inc, VM_RADIX_MAX(level), slot);
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for (; slot >= 0; slot--, index -= inc) {
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child = rnode->rn_child[slot];
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if (child)
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break;
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}
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}
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rnode = child;
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level--;
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}
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if (rnode) {
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for (; slot >= 0; slot--, index--) {
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if (rnode->rn_child[slot])
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return (rnode->rn_child[slot]);
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}
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}
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if (index != -1)
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goto restart;
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return (NULL);
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}
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/*
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* Remove the specified index from the tree. If possible the height of the
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* tree is adjusted after deletion. The value stored at index is returned
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* panics if the key is not present.
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*/
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void *
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vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index)
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{
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struct vm_radix_node *stack[VM_RADIX_LIMIT];
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struct vm_radix_node *rnode;
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void *val;
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int level;
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int slot;
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KASSERT(index <= VM_RADIX_MAX(rtree->rt_height),
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("vm_radix_remove: %p index %jd out of range %jd.",
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rtree, index, VM_RADIX_MAX(rtree->rt_height)));
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val = NULL;
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rnode = rtree->rt_root;
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level = rtree->rt_height - 1;
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/*
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* Find the node and record the path in stack.
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*/
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while (level && rnode) {
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stack[level] = rnode;
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slot = vm_radix_slot(index, level);
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rnode = rnode->rn_child[slot];
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CTR5(KTR_VM,
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"remove: tree %p, index %p, level %d, slot %d, child %p",
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rtree, (void *)index, level, slot, rnode->rn_child[slot]);
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level--;
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}
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slot = vm_radix_slot(index, 0);
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KASSERT(rnode != NULL && rnode->rn_child[slot] != NULL,
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("vm_radix_remove: index %jd not present in the tree.\n", index));
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val = rnode->rn_child[slot];
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for (;;) {
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rnode->rn_child[slot] = NULL;
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rnode->rn_count--;
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if (rnode->rn_count > 0)
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break;
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vm_radix_node_put(rnode);
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if (rnode == rtree->rt_root) {
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rtree->rt_root = NULL;
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rtree->rt_height = 0;
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break;
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}
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rnode = stack[++level];
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slot = vm_radix_slot(index, level);
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}
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return (val);
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}
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/*
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* Attempts to reduce the height of the tree.
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*/
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void
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vm_radix_shrink(struct vm_radix *rtree)
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{
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struct vm_radix_node *tmp;
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if (rtree->rt_root == NULL)
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return;
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/* Adjust the height of the tree. */
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while (rtree->rt_root->rn_count == 1 &&
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rtree->rt_root->rn_child[0] != NULL) {
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tmp = rtree->rt_root;
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rtree->rt_root = tmp->rn_child[0];
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rtree->rt_height--;
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tmp->rn_count--;
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vm_radix_node_put(tmp);
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}
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/* Finally see if we have an empty tree. */
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if (rtree->rt_root->rn_count == 0) {
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vm_radix_node_put(rtree->rt_root);
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rtree->rt_root = NULL;
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rtree->rt_height = 0;
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}
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}
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