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chg: dev: Remove locking from rdataslab_getownercase()

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Under normal circumstances, the case bitfield in the slabheader should
be set only once.  By actually (soft-)enforcing this, the read locking
can be completely removed from the rdataslab_getownercase() as we can
check whether the case has been already set or not and making everything
immutable once the case has been set.

Merge branch 'ondrej/remove-locking-from-slabheader-ownercase' into 'main'

See merge request isc-projects/bind9!10843
This commit is contained in:
Ondřej Surý 2025-08-15 07:36:13 +02:00
commit 9fc10b60f7
5 changed files with 114 additions and 108 deletions
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32
lib/dns/qpcache.c
View File

@ -59,6 +59,7 @@
#include "db_p.h"
#include "qpcache_p.h"
#include "rdataslab_p.h"
#ifndef DNS_QPCACHE_LOG_STATS_LEVEL
#define DNS_QPCACHE_LOG_STATS_LEVEL 3
@ -71,37 +72,6 @@
goto failure; \
} while (0)
#define EXISTS(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NONEXISTENT) == 0)
#define NXDOMAIN(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NXDOMAIN) != 0)
#define STALE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STALE) != 0)
#define STALE_WINDOW(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STALE_WINDOW) != 0)
#define OPTOUT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_OPTOUT) != 0)
#define NEGATIVE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NEGATIVE) != 0)
#define PREFETCH(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_PREFETCH) != 0)
#define ZEROTTL(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_ZEROTTL) != 0)
#define ANCIENT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_ANCIENT) != 0)
#define STATCOUNT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STATCOUNT) != 0)
#define STALE_TTL(header, qpdb) \
(NXDOMAIN(header) ? 0 : qpdb->common.serve_stale_ttl)

50
lib/dns/qpzone.c
View File

@ -62,6 +62,7 @@
#include "db_p.h"
#include "qpzone_p.h"
#include "rdataslab_p.h"
#define CHECK(op) \
do { \
@ -70,22 +71,6 @@
goto failure; \
} while (0)
#define NONEXISTENT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NONEXISTENT) != 0)
#define IGNORE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_IGNORE) != 0)
#define RESIGN(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_RESIGN) != 0)
#define OPTOUT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_OPTOUT) != 0)
#define STATCOUNT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STATCOUNT) != 0)
#define HEADERNODE(h) ((qpznode_t *)((h)->node))
#define QPDB_ATTR_LOADED 0x01
@ -1123,7 +1108,7 @@ setnsec3parameters(dns_db_t *db, qpz_version_t *version) {
if (header->serial <= version->serial &&
!IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -1655,7 +1640,7 @@ qpzone_findrdataset(dns_db_t *db, dns_dbnode_t *dbnode,
header_next = header->next;
do {
if (header->serial <= serial && !IGNORE(header)) {
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -1787,7 +1772,7 @@ cname_and_other(qpznode_t *node, uint32_t serial) {
do {
if (header->serial <= serial && !IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -1805,7 +1790,7 @@ cname_and_other(qpznode_t *node, uint32_t serial) {
do {
if (header->serial <= serial && !IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -1862,7 +1847,7 @@ recordsize(dns_slabheader_t *header, unsigned int namelen) {
static void
maybe_update_recordsandsize(bool add, qpz_version_t *version,
dns_slabheader_t *header, unsigned int namelen) {
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
return;
}
@ -1934,7 +1919,7 @@ add(qpzonedb_t *qpdb, qpznode_t *node, const dns_name_t *nodename,
* we'll try to create a new rdataset that is the union
* of 'newheader' and 'header'.
*/
if (merge && !NONEXISTENT(header)) {
if (merge && EXISTS(header)) {
unsigned int flags = 0;
INSIST(version->serial >= header->serial);
merged = NULL;
@ -2043,7 +2028,7 @@ add(qpzonedb_t *qpdb, qpznode_t *node, const dns_name_t *nodename,
*
* If we're trying to delete the type, don't bother.
*/
if (NONEXISTENT(newheader)) {
if (!EXISTS(newheader)) {
dns_slabheader_destroy(&newheader);
return DNS_R_UNCHANGED;
}
@ -2751,7 +2736,7 @@ step(qpz_search_t *search, dns_qpiter_t *it, direction_t direction,
if (header->serial <= search->serial &&
!IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -2914,7 +2899,7 @@ find_wildcard(qpz_search_t *search, qpznode_t **nodep, const dns_name_t *qname,
for (header = node->data; header != NULL; header = header->next)
{
if (header->serial <= search->serial &&
!IGNORE(header) && !NONEXISTENT(header))
!IGNORE(header) && EXISTS(header))
{
break;
}
@ -2954,8 +2939,7 @@ find_wildcard(qpz_search_t *search, qpznode_t **nodep, const dns_name_t *qname,
header = header->next)
{
if (header->serial <= search->serial &&
!IGNORE(header) &&
!NONEXISTENT(header))
!IGNORE(header) && EXISTS(header))
{
break;
}
@ -3141,7 +3125,7 @@ again:
if (header->serial <= search->serial &&
!IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -3286,7 +3270,7 @@ qpzone_check_zonecut(qpznode_t *node, void *arg DNS__DB_FLARG) {
if (header->serial <= search->serial &&
!IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -3613,7 +3597,7 @@ found:
do {
if (header->serial <= search.serial && !IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -4130,7 +4114,7 @@ rdatasetiter_first(dns_rdatasetiter_t *iterator DNS__DB_FLARG) {
if (header->serial <= version->serial &&
!IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -4183,7 +4167,7 @@ rdatasetiter_next(dns_rdatasetiter_t *iterator DNS__DB_FLARG) {
if (header->serial <= version->serial &&
!IGNORE(header))
{
if (NONEXISTENT(header)) {
if (!EXISTS(header)) {
header = NULL;
}
break;
@ -4994,7 +4978,7 @@ qpzone_subtractrdataset(dns_db_t *db, dns_dbnode_t *dbnode,
while (header != NULL && IGNORE(header)) {
header = header->down;
}
if (header != NULL && !NONEXISTENT(header)) {
if (header != NULL && EXISTS(header)) {
unsigned int flags = 0;
subresult = NULL;
result = ISC_R_SUCCESS;

75
lib/dns/rdataslab.c
View File

@ -18,6 +18,7 @@
#include <stdlib.h>
#include <isc/ascii.h>
#include <isc/atomic.h>
#include <isc/mem.h>
#include <isc/region.h>
#include <isc/result.h>
@ -30,18 +31,7 @@
#include <dns/rdataslab.h>
#include <dns/stats.h>
#define CASESET(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_CASESET) != 0)
#define CASEFULLYLOWER(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_CASEFULLYLOWER) != 0)
#define NONEXISTENT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NONEXISTENT) != 0)
#define NEGATIVE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NEGATIVE) != 0)
#include "rdataslab_p.h"
/*
* The rdataslab structure allows iteration to occur in both load order
@ -844,36 +834,38 @@ dns_slabheader_raw(dns_slabheader_t *header) {
void
dns_slabheader_setownercase(dns_slabheader_t *header, const dns_name_t *name) {
unsigned int i;
bool fully_lower;
REQUIRE(!CASESET(header));
bool casefullylower = true;
/*
* We do not need to worry about label lengths as they are all
* less than or equal to 63.
*/
memset(header->upper, 0, sizeof(header->upper));
fully_lower = true;
for (i = 0; i < name->length; i++) {
for (size_t i = 0; i < name->length; i++) {
if (isupper(name->ndata[i])) {
header->upper[i / 8] |= 1 << (i % 8);
fully_lower = false;
casefullylower = false;
}
}
DNS_SLABHEADER_SETATTR(header, DNS_SLABHEADERATTR_CASESET);
if (fully_lower) {
if (casefullylower) {
DNS_SLABHEADER_SETATTR(header,
DNS_SLABHEADERATTR_CASEFULLYLOWER);
}
DNS_SLABHEADER_SETATTR(header, DNS_SLABHEADERATTR_CASESET);
}
void
dns_slabheader_copycase(dns_slabheader_t *dest, dns_slabheader_t *src) {
REQUIRE(!CASESET(dest));
if (CASESET(src)) {
uint_least16_t attr = DNS_SLABHEADER_GETATTR(
src, DNS_SLABHEADERATTR_CASESET |
DNS_SLABHEADERATTR_CASEFULLYLOWER);
DNS_SLABHEADER_SETATTR(dest, attr);
memmove(dest->upper, src->upper, sizeof(src->upper));
if (CASEFULLYLOWER(src)) {
DNS_SLABHEADER_SETATTR(
dest, DNS_SLABHEADERATTR_CASEFULLYLOWER);
}
DNS_SLABHEADER_SETATTR(dest, DNS_SLABHEADERATTR_CASESET);
}
}
@ -915,10 +907,10 @@ dns_slabheader_destroy(dns_slabheader_t **headerp) {
isc_mem_t *mctx = header->node->mctx;
dns_db_deletedata(header->node, header);
if (NONEXISTENT(header)) {
size = sizeof(*header);
} else {
if (EXISTS(header)) {
size = dns_rdataslab_size(header);
} else {
size = sizeof(*header);
}
isc_mem_put(mctx, header, size);
@ -1209,7 +1201,10 @@ static void
rdataset_setownercase(dns_rdataset_t *rdataset, const dns_name_t *name) {
dns_slabheader_t *header = dns_rdataset_getheader(rdataset);
DNS_SLABHEADER_CLRATTR(header, DNS_SLABHEADERATTR_CASEFULLYLOWER);
/* The case could be set just once for the same header */
if (CASESET(header)) {
return;
}
dns_db_locknode(header->node, isc_rwlocktype_write);
dns_slabheader_setownercase(header, name);
@ -1222,26 +1217,26 @@ rdataset_getownercase(const dns_rdataset_t *rdataset, dns_name_t *name) {
uint8_t mask = (1 << 7);
uint8_t bits = 0;
if (!CASESET(header)) {
return;
}
if (CASEFULLYLOWER(header)) {
isc_ascii_lowercopy(name->ndata, name->ndata, name->length);
return;
}
dns_db_locknode(header->node, isc_rwlocktype_read);
if (CASESET(header)) {
uint8_t *nd = name->ndata;
for (size_t i = 0; i < name->length; i++) {
if (mask == (1 << 7)) {
bits = header->upper[i / 8];
mask = 1;
} else {
mask <<= 1;
}
nd[i] = (bits & mask) ? isc_ascii_toupper(nd[i])
: isc_ascii_tolower(nd[i]);
uint8_t *nd = name->ndata;
for (size_t i = 0; i < name->length; i++) {
if (mask == (1 << 7)) {
bits = header->upper[i / 8];
mask = 1;
} else {
mask <<= 1;
}
nd[i] = (bits & mask) ? isc_ascii_toupper(nd[i])
: isc_ascii_tolower(nd[i]);
}
dns_db_unlocknode(header->node, isc_rwlocktype_read);
}
static dns_slabheader_t *

59
lib/dns/rdataslab_p.h Normal file
View File

@ -0,0 +1,59 @@
/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
#pragma once
#include <dns/rdataslab.h>
#define ANCIENT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_ANCIENT) != 0)
#define CASEFULLYLOWER(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_CASEFULLYLOWER) != 0)
#define CASESET(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_CASESET) != 0)
#define EXISTS(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NONEXISTENT) == 0)
#define IGNORE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_IGNORE) != 0)
#define NEGATIVE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NEGATIVE) != 0)
#define NXDOMAIN(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_NXDOMAIN) != 0)
#define OPTOUT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_OPTOUT) != 0)
#define PREFETCH(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_PREFETCH) != 0)
#define RESIGN(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_RESIGN) != 0)
#define STALE(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STALE) != 0)
#define STALE_WINDOW(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STALE_WINDOW) != 0)
#define STATCOUNT(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_STATCOUNT) != 0)
#define ZEROTTL(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_ZEROTTL) != 0)

6
tests/dns/qpzone_test.c
View File

@ -34,6 +34,8 @@
#include <dns/rdatastruct.h>
#define KEEP_BEFORE
#include "rdataslab_p.h"
/* Include the main file */
#pragma GCC diagnostic push
@ -45,10 +47,6 @@
#undef CHECK
#include <tests/dns.h>
#define CASESET(header) \
((atomic_load_acquire(&(header)->attributes) & \
DNS_SLABHEADERATTR_CASESET) != 0)
const char *ownercase_vectors[12][2] = {
{
"AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz",