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Convert rwlock in isc_log_t to RCU

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The isc_log_t contains a isc_logconfig_t that is swapped, dereferenced
or accessed its fields through a mutex. Instead of protecting it with a
rwlock, use RCU.
This commit is contained in:
Aydın Mercan 2023-12-19 10:41:15 +03:00
parent 0a7b0c3896
commit a911949ebc
No known key found for this signature in database
1 changed files with 43 additions and 59 deletions
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102
lib/isc/log.c
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@ -30,11 +30,11 @@
#include <isc/log.h> #include <isc/log.h>
#include <isc/magic.h> #include <isc/magic.h>
#include <isc/mem.h> #include <isc/mem.h>
#include <isc/rwlock.h>
#include <isc/stdio.h> #include <isc/stdio.h>
#include <isc/string.h> #include <isc/string.h>
#include <isc/thread.h> #include <isc/thread.h>
#include <isc/time.h> #include <isc/time.h>
#include <isc/urcu.h>
#include <isc/util.h> #include <isc/util.h>
#define LCTX_MAGIC ISC_MAGIC('L', 'c', 't', 'x') #define LCTX_MAGIC ISC_MAGIC('L', 'c', 't', 'x')
@ -143,8 +143,7 @@ struct isc_log {
isc_logmodule_t *modules; isc_logmodule_t *modules;
unsigned int module_count; unsigned int module_count;
atomic_int_fast32_t debug_level; atomic_int_fast32_t debug_level;
isc_rwlock_t lcfg_rwl; /* RCU-protected pointer */
/* Locked by isc_log lcfg_rwl */
isc_logconfig_t *logconfig; isc_logconfig_t *logconfig;
isc_mutex_t lock; isc_mutex_t lock;
/* Locked by isc_log lock. */ /* Locked by isc_log lock. */
@ -254,19 +253,6 @@ isc_log_create(isc_mem_t *mctx, isc_log_t **lctxp, isc_logconfig_t **lcfgp) {
REQUIRE(lcfgp == NULL || *lcfgp == NULL); REQUIRE(lcfgp == NULL || *lcfgp == NULL);
lctx = isc_mem_get(mctx, sizeof(*lctx)); lctx = isc_mem_get(mctx, sizeof(*lctx));
lctx->mctx = NULL;
isc_mem_attach(mctx, &lctx->mctx);
lctx->categories = NULL;
lctx->category_count = 0;
lctx->modules = NULL;
lctx->module_count = 0;
atomic_init(&lctx->debug_level, 0);
ISC_LIST_INIT(lctx->messages);
isc_mutex_init(&lctx->lock);
isc_rwlock_init(&lctx->lcfg_rwl);
/* /*
* Normally setting the magic number is the last step done * Normally setting the magic number is the last step done
* in a creation function, but a valid log context is needed * in a creation function, but a valid log context is needed
@ -274,12 +260,16 @@ isc_log_create(isc_mem_t *mctx, isc_log_t **lctxp, isc_logconfig_t **lcfgp) {
* If either fails, the lctx is destroyed and not returned * If either fails, the lctx is destroyed and not returned
* to the caller. * to the caller.
*/ */
lctx->magic = LCTX_MAGIC; *lctx = (isc_log_t){
.magic = LCTX_MAGIC,
.messages = ISC_LIST_INITIALIZER,
};
isc_mem_attach(mctx, &lctx->mctx);
isc_mutex_init(&lctx->lock);
isc_log_registercategories(lctx, isc_categories); isc_log_registercategories(lctx, isc_categories);
isc_log_registermodules(lctx, isc_modules); isc_log_registermodules(lctx, isc_modules);
isc_logconfig_create(lctx, &lcfg); isc_logconfig_create(lctx, &lcfg);
sync_channellist(lcfg); sync_channellist(lcfg);
lctx->logconfig = lcfg; lctx->logconfig = lcfg;
@ -302,15 +292,12 @@ isc_logconfig_create(isc_log_t *lctx, isc_logconfig_t **lcfgp) {
lcfg = isc_mem_get(lctx->mctx, sizeof(*lcfg)); lcfg = isc_mem_get(lctx->mctx, sizeof(*lcfg));
lcfg->lctx = lctx; *lcfg = (isc_logconfig_t){
lcfg->channellists = NULL; .magic = LCFG_MAGIC,
lcfg->channellist_count = 0; .lctx = lctx,
lcfg->duplicate_interval = 0; .channels = ISC_LIST_INITIALIZER,
lcfg->highest_level = level; .highest_level = level,
lcfg->tag = NULL; };
lcfg->dynamic = false;
ISC_LIST_INIT(lcfg->channels);
lcfg->magic = LCFG_MAGIC;
/* /*
* Create the default channels: * Create the default channels:
@ -320,11 +307,11 @@ isc_logconfig_create(isc_log_t *lctx, isc_logconfig_t **lcfgp) {
isc_log_createchannel(lcfg, "default_syslog", ISC_LOG_TOSYSLOG, level, isc_log_createchannel(lcfg, "default_syslog", ISC_LOG_TOSYSLOG, level,
&destination, 0); &destination, 0);
destination.file.stream = stderr; destination.file = (isc_logfile_t){
destination.file.name = NULL; .stream = stderr,
destination.file.versions = ISC_LOG_ROLLNEVER; .versions = ISC_LOG_ROLLNEVER,
destination.file.suffix = isc_log_rollsuffix_increment; .suffix = isc_log_rollsuffix_increment,
destination.file.maximum_size = 0; };
isc_log_createchannel(lcfg, "default_stderr", ISC_LOG_TOFILEDESC, level, isc_log_createchannel(lcfg, "default_stderr", ISC_LOG_TOFILEDESC, level,
&destination, ISC_LOG_PRINTTIME); &destination, ISC_LOG_PRINTTIME);
@ -335,11 +322,11 @@ isc_logconfig_create(isc_log_t *lctx, isc_logconfig_t **lcfgp) {
*/ */
default_channel.channel = ISC_LIST_HEAD(lcfg->channels); default_channel.channel = ISC_LIST_HEAD(lcfg->channels);
destination.file.stream = stderr; destination.file = (isc_logfile_t){
destination.file.name = NULL; .stream = stderr,
destination.file.versions = ISC_LOG_ROLLNEVER; .versions = ISC_LOG_ROLLNEVER,
destination.file.suffix = isc_log_rollsuffix_increment; .suffix = isc_log_rollsuffix_increment,
destination.file.maximum_size = 0; };
isc_log_createchannel(lcfg, "default_debug", ISC_LOG_TOFILEDESC, isc_log_createchannel(lcfg, "default_debug", ISC_LOG_TOFILEDESC,
ISC_LOG_DYNAMIC, &destination, ISC_LOG_PRINTTIME); ISC_LOG_DYNAMIC, &destination, ISC_LOG_PRINTTIME);
@ -364,11 +351,9 @@ isc_logconfig_use(isc_log_t *lctx, isc_logconfig_t *lcfg) {
*/ */
sync_channellist(lcfg); sync_channellist(lcfg);
WRLOCK(&lctx->lcfg_rwl); old_cfg = rcu_xchg_pointer(&lctx->logconfig, lcfg);
old_cfg = lctx->logconfig;
lctx->logconfig = lcfg;
sync_highest_level(lctx, lcfg); sync_highest_level(lctx, lcfg);
WRUNLOCK(&lctx->lcfg_rwl); synchronize_rcu();
isc_logconfig_destroy(&old_cfg); isc_logconfig_destroy(&old_cfg);
} }
@ -391,16 +376,13 @@ isc_log_destroy(isc_log_t **lctxp) {
atomic_store_release(&lctx->highest_level, 0); atomic_store_release(&lctx->highest_level, 0);
atomic_store_release(&lctx->dynamic, false); atomic_store_release(&lctx->dynamic, false);
WRLOCK(&lctx->lcfg_rwl); lcfg = rcu_xchg_pointer(&lctx->logconfig, NULL);
lcfg = lctx->logconfig; synchronize_rcu();
lctx->logconfig = NULL;
WRUNLOCK(&lctx->lcfg_rwl);
if (lcfg != NULL) { if (lcfg != NULL) {
isc_logconfig_destroy(&lcfg); isc_logconfig_destroy(&lcfg);
} }
isc_rwlock_destroy(&lctx->lcfg_rwl);
isc_mutex_destroy(&lctx->lock); isc_mutex_destroy(&lctx->lock);
while ((message = ISC_LIST_HEAD(lctx->messages)) != NULL) { while ((message = ISC_LIST_HEAD(lctx->messages)) != NULL) {
@ -440,9 +422,9 @@ isc_logconfig_destroy(isc_logconfig_t **lcfgp) {
*/ */
REQUIRE(lcfg->lctx != NULL); REQUIRE(lcfg->lctx != NULL);
RDLOCK(&lcfg->lctx->lcfg_rwl); rcu_read_lock();
REQUIRE(lcfg->lctx->logconfig != lcfg); REQUIRE(rcu_dereference(lcfg->lctx->logconfig) != lcfg);
RDUNLOCK(&lcfg->lctx->lcfg_rwl); rcu_read_unlock();
mctx = lcfg->lctx->mctx; mctx = lcfg->lctx->mctx;
@ -756,9 +738,11 @@ isc_log_usechannel(isc_logconfig_t *lcfg, const char *name,
/* /*
* Update the highest logging level, if the current lcfg is in use. * Update the highest logging level, if the current lcfg is in use.
*/ */
if (lcfg->lctx->logconfig == lcfg) { rcu_read_lock();
if (rcu_dereference(lcfg->lctx->logconfig) == lcfg) {
sync_highest_level(lctx, lcfg); sync_highest_level(lctx, lcfg);
} }
rcu_read_unlock();
return (ISC_R_SUCCESS); return (ISC_R_SUCCESS);
} }
@ -825,8 +809,8 @@ isc_log_setdebuglevel(isc_log_t *lctx, unsigned int level) {
* Close ISC_LOG_DEBUGONLY channels if level is zero. * Close ISC_LOG_DEBUGONLY channels if level is zero.
*/ */
if (level == 0) { if (level == 0) {
RDLOCK(&lctx->lcfg_rwl); rcu_read_lock();
isc_logconfig_t *lcfg = lctx->logconfig; isc_logconfig_t *lcfg = rcu_dereference(lctx->logconfig);
if (lcfg != NULL) { if (lcfg != NULL) {
LOCK(&lctx->lock); LOCK(&lctx->lock);
for (isc_logchannel_t *channel = for (isc_logchannel_t *channel =
@ -844,7 +828,7 @@ isc_log_setdebuglevel(isc_log_t *lctx, unsigned int level) {
} }
UNLOCK(&lctx->lock); UNLOCK(&lctx->lock);
} }
RDUNLOCK(&lctx->lcfg_rwl); rcu_read_unlock();
} }
} }
@ -903,8 +887,8 @@ void
isc_log_closefilelogs(isc_log_t *lctx) { isc_log_closefilelogs(isc_log_t *lctx) {
REQUIRE(VALID_CONTEXT(lctx)); REQUIRE(VALID_CONTEXT(lctx));
RDLOCK(&lctx->lcfg_rwl); rcu_read_lock();
isc_logconfig_t *lcfg = lctx->logconfig; isc_logconfig_t *lcfg = rcu_dereference(lctx->logconfig);
if (lcfg != NULL) { if (lcfg != NULL) {
LOCK(&lctx->lock); LOCK(&lctx->lock);
for (isc_logchannel_t *channel = ISC_LIST_HEAD(lcfg->channels); for (isc_logchannel_t *channel = ISC_LIST_HEAD(lcfg->channels);
@ -919,7 +903,7 @@ isc_log_closefilelogs(isc_log_t *lctx) {
} }
UNLOCK(&lctx->lock); UNLOCK(&lctx->lock);
} }
RDUNLOCK(&lctx->lcfg_rwl); rcu_read_unlock();
} }
/**** /****
@ -1521,12 +1505,12 @@ isc_log_doit(isc_log_t *lctx, isc_logcategory_t *category,
iso8601l_string[0] = '\0'; iso8601l_string[0] = '\0';
iso8601z_string[0] = '\0'; iso8601z_string[0] = '\0';
RDLOCK(&lctx->lcfg_rwl); rcu_read_lock();
LOCK(&lctx->lock); LOCK(&lctx->lock);
lctx->buffer[0] = '\0'; lctx->buffer[0] = '\0';
isc_logconfig_t *lcfg = lctx->logconfig; isc_logconfig_t *lcfg = rcu_dereference(lctx->logconfig);
category_channels = ISC_LIST_HEAD(lcfg->channellists[category->id]); category_channels = ISC_LIST_HEAD(lcfg->channellists[category->id]);
@ -1877,7 +1861,7 @@ isc_log_doit(isc_log_t *lctx, isc_logcategory_t *category,
unlock: unlock:
UNLOCK(&lctx->lock); UNLOCK(&lctx->lock);
RDUNLOCK(&lctx->lcfg_rwl); rcu_read_unlock();
} }
void void