266 lines
7.0 KiB
C
266 lines
7.0 KiB
C
/* $NetBSD: subr_hash.c,v 1.12 2021/06/13 14:58:49 simonb Exp $ */
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/*
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* Copyright (c) 1982, 1986, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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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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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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* @(#)kern_subr.c 8.4 (Berkeley) 2/14/95
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: subr_hash.c,v 1.12 2021/06/13 14:58:49 simonb Exp $");
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#include <sys/param.h>
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#include <sys/bitops.h>
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#include <sys/kmem.h>
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#include <sys/systm.h>
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#include <sys/pslist.h>
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#include <sys/rwlock.h>
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#include <sys/sysctl.h>
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static int hashstat_sysctl(SYSCTLFN_PROTO);
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static size_t
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hash_list_size(enum hashtype htype)
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{
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LIST_HEAD(, generic) *hashtbl_list;
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SLIST_HEAD(, generic) *hashtbl_slist;
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TAILQ_HEAD(, generic) *hashtbl_tailq;
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struct pslist_head *hashtbl_pslist;
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size_t esize;
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switch (htype) {
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case HASH_LIST:
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esize = sizeof(*hashtbl_list);
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break;
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case HASH_PSLIST:
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esize = sizeof(*hashtbl_pslist);
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break;
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case HASH_SLIST:
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esize = sizeof(*hashtbl_slist);
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break;
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case HASH_TAILQ:
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esize = sizeof(*hashtbl_tailq);
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break;
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default:
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panic("hashdone: invalid table type");
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}
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return esize;
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}
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/*
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* General routine to allocate a hash table.
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* Allocate enough memory to hold at least `elements' list-head pointers.
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* Return a pointer to the allocated space and set *hashmask to a pattern
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* suitable for masking a value to use as an index into the returned array.
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*/
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void *
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hashinit(u_int elements, enum hashtype htype, bool waitok, u_long *hashmask)
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{
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LIST_HEAD(, generic) *hashtbl_list;
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SLIST_HEAD(, generic) *hashtbl_slist;
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TAILQ_HEAD(, generic) *hashtbl_tailq;
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struct pslist_head *hashtbl_pslist;
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u_long hashsize, i;
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size_t esize;
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void *p;
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KASSERT(elements > 0);
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#define MAXELEMENTS (1U << ((sizeof(elements) * NBBY) - 1))
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if (elements > MAXELEMENTS)
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elements = MAXELEMENTS;
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hashsize = 1UL << (ilog2(elements - 1) + 1);
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esize = hash_list_size(htype);
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p = kmem_alloc(hashsize * esize, waitok ? KM_SLEEP : KM_NOSLEEP);
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if (p == NULL)
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return NULL;
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switch (htype) {
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case HASH_LIST:
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hashtbl_list = p;
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for (i = 0; i < hashsize; i++)
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LIST_INIT(&hashtbl_list[i]);
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break;
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case HASH_PSLIST:
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hashtbl_pslist = p;
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for (i = 0; i < hashsize; i++)
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PSLIST_INIT(&hashtbl_pslist[i]);
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break;
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case HASH_SLIST:
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hashtbl_slist = p;
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for (i = 0; i < hashsize; i++)
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SLIST_INIT(&hashtbl_slist[i]);
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break;
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case HASH_TAILQ:
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hashtbl_tailq = p;
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for (i = 0; i < hashsize; i++)
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TAILQ_INIT(&hashtbl_tailq[i]);
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break;
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}
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*hashmask = hashsize - 1;
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return p;
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}
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/*
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* Free memory from hash table previosly allocated via hashinit().
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*/
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void
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hashdone(void *hashtbl, enum hashtype htype, u_long hashmask)
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{
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const size_t esize = hash_list_size(htype);
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kmem_free(hashtbl, esize * (hashmask + 1));
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}
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/*
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* Support for hash statistics (vmstat -H / vmstat -h hashname).
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*/
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struct hashstat {
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const char *hs_name;
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hashstat_func_t hs_func;
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TAILQ_ENTRY(hashstat) hs_next;
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};
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TAILQ_HEAD(, hashstat) hashstat_list =
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TAILQ_HEAD_INITIALIZER(hashstat_list);
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static krwlock_t hashstat_lock;
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void
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hashstat_register(const char *name, hashstat_func_t func)
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{
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struct hashstat *hs;
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hs = kmem_alloc(sizeof(*hs), KM_SLEEP);
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hs->hs_name = name;
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hs->hs_func = func;
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rw_enter(&hashstat_lock, RW_WRITER);
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TAILQ_INSERT_TAIL(&hashstat_list, hs, hs_next);
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rw_exit(&hashstat_lock);
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}
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/*
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* sysctl support for returning kernel hash statistics.
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*
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* We (ab)use CTL_DESCRIBE and CTL_QUERY:
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* When passed an OID of CTL_DESCRIBE, return a list and description
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* of the available hashes.
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* When passed an OID of CTL_QUERY, use the hash name passed in the
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* "new" hash input as the name of a single hash to return stats on.
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*/
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static int
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hashstat_sysctl(SYSCTLFN_ARGS)
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{
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struct hashstat_sysctl hs;
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struct hashstat *hash;
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char queryname[SYSCTL_NAMELEN];
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size_t written;
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bool fill, query;
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int error;
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if (oldp == NULL) {
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*oldlenp = 0;
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TAILQ_FOREACH(hash, &hashstat_list, hs_next)
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*oldlenp += sizeof(hs);
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return 0;
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}
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error = 0;
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written = 0;
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if (namelen > 0 && name[0] == CTL_DESCRIBE)
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fill = false;
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else
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fill = true;
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if (namelen > 0 && name[0] == CTL_QUERY) {
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const struct hashstat_sysctl *h = newp;
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size_t s;
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if (h == NULL) {
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/* Can't QUERY one hash without supplying the hash name. */
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return EINVAL;
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}
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query = true;
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error = sysctl_copyinstr(l, h->hash_name, queryname,
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sizeof(queryname), &s);
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if (error)
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return error;
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} else {
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query = false;
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}
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sysctl_unlock();
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rw_enter(&hashstat_lock, RW_READER);
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TAILQ_FOREACH(hash, &hashstat_list, hs_next) {
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if (query && (strcmp(hash->hs_name, queryname) != 0)) {
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continue;
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}
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memset(&hs, 0, sizeof(hs));
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error = hash->hs_func(&hs, fill);
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if (error)
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break;
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error = sysctl_copyout(l, &hs, oldp, sizeof(hs));
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if (error)
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break;
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written += sizeof(hs);
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oldp = (char *)oldp + sizeof(hs);
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}
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rw_exit(&hashstat_lock);
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sysctl_relock();
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if (query && written == 0) /* query not found? */
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error = ENOENT;
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*oldlenp = written;
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return error;
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}
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SYSCTL_SETUP(sysctl_hash_setup, "sysctl hash stats setup")
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{
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rw_init(&hashstat_lock); /* as good a place as any for this */
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sysctl_createv(NULL, 0, NULL, NULL,
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CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
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CTLTYPE_STRUCT,
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"hashstat", SYSCTL_DESCR("kernel hash statistics"),
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hashstat_sysctl, 0, NULL, 0,
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CTL_KERN, CTL_CREATE, CTL_EOL);
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}
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