From 205c6be8955f5c90c5b3d2d47e302630337a966d Mon Sep 17 00:00:00 2001
From: Corey Farrell <git@cfware.com>
Date: Thu, 27 Sep 2018 20:32:21 -0400
Subject: [PATCH] lock: Improve performance of DEBUG_THREADS.
Add a volatile flag to lock tracking structures so we only need to use
the global lock when first initializing tracking.
Additionally add support for DEBUG_THREADS_LOOSE_ABI. This is used by
astobj2.c to eliminate storage for tracking fields when DEBUG_THREADS is
not defined.
Change-Id: Iabd650908901843e9fff47ef1c539f0e1b8cb13b
---
include/asterisk/astobj2.h | 3 +
include/asterisk/lock.h | 39 +++++++++---
main/astobj2.c | 4 ++
main/lock.c | 125 +++++++++++++------------------------
4 files changed, 81 insertions(+), 90 deletions(-)
diff --git a/include/asterisk/astobj2.h b/include/asterisk/astobj2.h
index 0e442dbe07..8e3a105c3c 100644
--- a/include/asterisk/astobj2.h
+++ b/include/asterisk/astobj2.h
@@ -752,6 +752,9 @@ int __ao2_trylock(void *a, enum ao2_lock_req lock_how, const char *file, const c
* lock address, this allows you to correlate against
* object address, to match objects to reported locks.
*
+ * \warning AO2 lock objects do not include tracking fields when
+ * DEBUG_THREADS is not enabled.
+ *
* \since 1.6.1
*/
void *ao2_object_get_lockaddr(void *obj);
diff --git a/include/asterisk/lock.h b/include/asterisk/lock.h
index a46d04799e..b409a27a1b 100644
--- a/include/asterisk/lock.h
+++ b/include/asterisk/lock.h
@@ -92,11 +92,11 @@
#define AST_LOCK_TRACK_INIT_VALUE { { NULL }, { 0 }, 0, { NULL }, { 0 }, PTHREAD_MUTEX_INIT_VALUE }
#endif
-#define AST_MUTEX_INIT_VALUE { PTHREAD_MUTEX_INIT_VALUE, NULL, 1 }
-#define AST_MUTEX_INIT_VALUE_NOTRACKING { PTHREAD_MUTEX_INIT_VALUE, NULL, 0 }
+#define AST_MUTEX_INIT_VALUE { PTHREAD_MUTEX_INIT_VALUE, NULL, {1, 0} }
+#define AST_MUTEX_INIT_VALUE_NOTRACKING { PTHREAD_MUTEX_INIT_VALUE, NULL, {0, 0} }
-#define AST_RWLOCK_INIT_VALUE { __AST_RWLOCK_INIT_VALUE, NULL, 1 }
-#define AST_RWLOCK_INIT_VALUE_NOTRACKING { __AST_RWLOCK_INIT_VALUE, NULL, 0 }
+#define AST_RWLOCK_INIT_VALUE { __AST_RWLOCK_INIT_VALUE, NULL, {1, 0} }
+#define AST_RWLOCK_INIT_VALUE_NOTRACKING { __AST_RWLOCK_INIT_VALUE, NULL, {0, 0} }
#define AST_MAX_REENTRANCY 10
@@ -120,6 +120,13 @@ struct ast_lock_track {
pthread_mutex_t reentr_mutex;
};
+struct ast_lock_track_flags {
+ /*! non-zero if lock tracking is enabled */
+ unsigned int tracking:1;
+ /*! non-zero if track is setup */
+ volatile unsigned int setup:1;
+};
+
/*! \brief Structure for mutex and tracking information.
*
* We have tracking information in this structure regardless of DEBUG_THREADS being enabled.
@@ -127,9 +134,18 @@ struct ast_lock_track {
*/
struct ast_mutex_info {
pthread_mutex_t mutex;
- /*! Track which thread holds this mutex */
+#if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI)
+ /*!
+ * These fields are renamed to ensure they are never used when
+ * DEBUG_THREADS is not defined.
+ */
+ struct ast_lock_track *_track;
+ struct ast_lock_track_flags _flags;
+#elif defined(DEBUG_THREADS)
+ /*! Track which thread holds this mutex. */
struct ast_lock_track *track;
- unsigned int tracking:1;
+ struct ast_lock_track_flags flags;
+#endif
};
/*! \brief Structure for rwlock and tracking information.
@@ -139,9 +155,18 @@ struct ast_mutex_info {
*/
struct ast_rwlock_info {
pthread_rwlock_t lock;
+#if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI)
+ /*!
+ * These fields are renamed to ensure they are never used when
+ * DEBUG_THREADS is not defined.
+ */
+ struct ast_lock_track *_track;
+ struct ast_lock_track_flags _flags;
+#elif defined(DEBUG_THREADS)
/*! Track which thread holds this lock */
struct ast_lock_track *track;
- unsigned int tracking:1;
+ struct ast_lock_track_flags flags;
+#endif
};
typedef struct ast_mutex_info ast_mutex_t;
diff --git a/main/astobj2.c b/main/astobj2.c
index 91ebc1e2c9..d9d8a0ca78 100644
--- a/main/astobj2.c
+++ b/main/astobj2.c
@@ -25,6 +25,10 @@
<support_level>core</support_level>
***/
+/* This reduces the size of lock structures within astobj2 objects when
+ * DEBUG_THREADS is not defined. */
+#define DEBUG_THREADS_LOOSE_ABI
+
#include "asterisk.h"
#include "asterisk/_private.h"
diff --git a/main/lock.c b/main/lock.c
index dec814fb14..5ad9e134b7 100644
--- a/main/lock.c
+++ b/main/lock.c
@@ -72,21 +72,16 @@ static void __dump_backtrace(struct ast_bt *bt, int canlog)
#ifdef DEBUG_THREADS
AST_MUTEX_DEFINE_STATIC(reentrancy_lock);
-static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **plt)
+static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **plt,
+ struct ast_lock_track_flags *flags, int no_setup)
{
pthread_mutexattr_t reentr_attr;
struct ast_lock_track *lt;
- /* It's a bit painful to lock a global mutex for every access to the
- * reentrancy structure, but it's necessary to ensure that we don't
- * double-allocate the structure or double-initialize the reentr_mutex.
- *
- * If you'd like to replace this with a double-checked lock, be sure to
- * properly volatile-ize everything to avoid optimizer bugs.
- *
- * We also have to use the underlying pthread calls for manipulating
- * the mutex, because this is called from the Asterisk mutex code.
- */
+ if (!flags->tracking || flags->setup) {
+ return *plt;
+ }
+
pthread_mutex_lock(&reentrancy_lock.mutex);
if (*plt) {
@@ -94,6 +89,11 @@ static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **
return *plt;
}
+ if (no_setup) {
+ pthread_mutex_unlock(&reentrancy_lock.mutex);
+ return NULL;
+ }
+
lt = *plt = ast_std_calloc(1, sizeof(*lt));
if (!lt) {
fprintf(stderr, "%s: Failed to allocate lock tracking\n", __func__);
@@ -110,6 +110,7 @@ static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **
pthread_mutex_init(<->reentr_mutex, &reentr_attr);
pthread_mutexattr_destroy(&reentr_attr);
+ flags->setup = 1;
pthread_mutex_unlock(&reentrancy_lock.mutex);
return lt;
}
@@ -148,7 +149,8 @@ int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, con
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
t->track = NULL;
- t->tracking = tracking;
+ t->flags.tracking = tracking;
+ t->flags.setup = 0;
#endif /* DEBUG_THREADS */
pthread_mutexattr_init(&attr);
@@ -165,8 +167,8 @@ int __ast_pthread_mutex_destroy(const char *filename, int lineno, const char *fu
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = t->track;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 1);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
@@ -243,14 +245,10 @@ int __ast_pthread_mutex_lock(const char *filename, int lineno, const char *func,
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -360,14 +358,10 @@ int __ast_pthread_mutex_trylock(const char *filename, int lineno, const char *fu
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -420,7 +414,7 @@ int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *fun
#ifdef DEBUG_THREADS
struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
@@ -432,10 +426,7 @@ int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *fun
}
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
+ lt = ast_get_reentrancy(&t->track, &t->flags, 0);
if (lt) {
ast_reentrancy_lock(lt);
if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
@@ -543,7 +534,7 @@ int __ast_cond_wait(const char *filename, int lineno, const char *func,
#ifdef DEBUG_THREADS
struct ast_lock_track *lt = NULL;
struct ast_lock_track lt_orig;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
@@ -554,10 +545,7 @@ int __ast_cond_wait(const char *filename, int lineno, const char *func,
}
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
+ lt = ast_get_reentrancy(&t->track, &t->flags, 0);
if (lt) {
ast_reentrancy_lock(lt);
if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
@@ -611,7 +599,7 @@ int __ast_cond_timedwait(const char *filename, int lineno, const char *func,
#ifdef DEBUG_THREADS
struct ast_lock_track *lt = NULL;
struct ast_lock_track lt_orig;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
@@ -622,10 +610,7 @@ int __ast_cond_timedwait(const char *filename, int lineno, const char *func,
}
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
+ lt = ast_get_reentrancy(&t->track, &t->flags, 0);
if (lt) {
ast_reentrancy_lock(lt);
if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
@@ -688,7 +673,8 @@ int __ast_rwlock_init(int tracking, const char *filename, int lineno, const char
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
t->track = NULL;
- t->tracking = tracking;
+ t->flags.tracking = tracking;
+ t->flags.setup = 0;
#endif /* DEBUG_THREADS */
pthread_rwlockattr_init(&attr);
@@ -706,8 +692,8 @@ int __ast_rwlock_destroy(const char *filename, int lineno, const char *func, con
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = t->track;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 1);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
if (t->lock == ((pthread_rwlock_t) __AST_RWLOCK_INIT_VALUE)) {
@@ -754,7 +740,7 @@ int __ast_rwlock_unlock(const char *filename, int line, const char *func, ast_rw
#ifdef DEBUG_THREADS
struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
int lock_found = 0;
@@ -767,10 +753,7 @@ int __ast_rwlock_unlock(const char *filename, int line, const char *func, ast_rw
}
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
+ lt = ast_get_reentrancy(&t->track, &t->flags, 0);
if (lt) {
ast_reentrancy_lock(lt);
if (lt->reentrancy) {
@@ -827,14 +810,10 @@ int __ast_rwlock_rdlock(const char *filename, int line, const char *func, ast_rw
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -929,14 +908,10 @@ int __ast_rwlock_wrlock(const char *filename, int line, const char *func, ast_rw
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -1031,14 +1006,10 @@ int __ast_rwlock_timedrdlock(const char *filename, int line, const char *func, a
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -1117,14 +1088,10 @@ int __ast_rwlock_timedwrlock(const char *filename, int line, const char *func, a
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
- int canlog = t->tracking && strcmp(filename, "logger.c");
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
+ int canlog = t->flags.tracking && strcmp(filename, "logger.c");
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -1202,13 +1169,9 @@ int __ast_rwlock_tryrdlock(const char *filename, int line, const char *func, ast
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
@@ -1256,13 +1219,9 @@ int __ast_rwlock_trywrlock(const char *filename, int line, const char *func, ast
int res;
#ifdef DEBUG_THREADS
- struct ast_lock_track *lt = NULL;
+ struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
struct ast_bt *bt = NULL;
- if (t->tracking) {
- lt = ast_get_reentrancy(&t->track);
- }
-
if (lt) {
#ifdef HAVE_BKTR
struct ast_bt tmp;
--
GitLab