diff --git a/channels/chan_agent.c b/channels/chan_agent.c
index decf022c45f6a4dca9237da9d47543dac94c2733..8d22eadf9702900c95eb184d38649f0917191c63 100644
--- a/channels/chan_agent.c
+++ b/channels/chan_agent.c
@@ -1520,9 +1520,7 @@ static int agent_logoff(const char *agent, int soft)
ast_mutex_lock(&p->lock);
while (p->owner && ast_channel_trylock(p->owner)) {
- ast_mutex_unlock(&p->lock);
- usleep(1);
- ast_mutex_lock(&p->lock);
+ DEADLOCK_AVOIDANCE(&p->lock);
}
if (p->owner) {
ast_softhangup(p->owner, AST_SOFTHANGUP_EXPLICIT);
@@ -1530,9 +1528,7 @@ static int agent_logoff(const char *agent, int soft)
}
while (p->chan && ast_channel_trylock(p->chan)) {
- ast_mutex_unlock(&p->lock);
- usleep(1);
- ast_mutex_lock(&p->lock);
+ DEADLOCK_AVOIDANCE(&p->lock);
}
if (p->chan) {
ast_softhangup(p->chan, AST_SOFTHANGUP_EXPLICIT);
diff --git a/channels/chan_alsa.c b/channels/chan_alsa.c
index b4e194b13415ad38ba6e96653148ed5bf73c7f3f..5c2a3957a16696bcb692da0af994621dd6d0db58 100644
--- a/channels/chan_alsa.c
+++ b/channels/chan_alsa.c
@@ -297,9 +297,7 @@ static int alsa_text(struct ast_channel *c, const char *text)
static void grab_owner(void)
{
while (alsa.owner && ast_channel_trylock(alsa.owner)) {
- ast_mutex_unlock(&alsalock);
- usleep(1);
- ast_mutex_lock(&alsalock);
+ DEADLOCK_AVOIDANCE(&alsalock);
}
}
diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index 7ce45d3c47c4da6904bb9936173b2208509ea6b4..174a05a28f308bd5cb3f7614f4c37b6434dc17b3 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -1746,9 +1746,7 @@ static int iax2_queue_frame(int callno, struct ast_frame *f)
if (iaxs[callno] && iaxs[callno]->owner) {
if (ast_channel_trylock(iaxs[callno]->owner)) {
/* Avoid deadlock by pausing and trying again */
- ast_mutex_unlock(&iaxsl[callno]);
- usleep(1);
- ast_mutex_lock(&iaxsl[callno]);
+ DEADLOCK_AVOIDANCE(&iaxsl[callno]);
} else {
ast_queue_frame(iaxs[callno]->owner, f);
ast_channel_unlock(iaxs[callno]->owner);
@@ -1779,9 +1777,7 @@ static int iax2_queue_hangup(int callno)
if (iaxs[callno] && iaxs[callno]->owner) {
if (ast_channel_trylock(iaxs[callno]->owner)) {
/* Avoid deadlock by pausing and trying again */
- ast_mutex_unlock(&iaxsl[callno]);
- usleep(1);
- ast_mutex_lock(&iaxsl[callno]);
+ DEADLOCK_AVOIDANCE(&iaxsl[callno]);
} else {
ast_queue_hangup(iaxs[callno]->owner);
ast_channel_unlock(iaxs[callno]->owner);
@@ -1813,9 +1809,7 @@ static int iax2_queue_control_data(int callno,
if (iaxs[callno] && iaxs[callno]->owner) {
if (ast_channel_trylock(iaxs[callno]->owner)) {
/* Avoid deadlock by pausing and trying again */
- ast_mutex_unlock(&iaxsl[callno]);
- usleep(1);
- ast_mutex_lock(&iaxsl[callno]);
+ DEADLOCK_AVOIDANCE(&iaxsl[callno]);
} else {
ast_queue_control_data(iaxs[callno]->owner, control, data, datalen);
ast_channel_unlock(iaxs[callno]->owner);
@@ -3773,9 +3767,7 @@ static void lock_both(unsigned short callno0, unsigned short callno1)
{
ast_mutex_lock(&iaxsl[callno0]);
while (ast_mutex_trylock(&iaxsl[callno1])) {
- ast_mutex_unlock(&iaxsl[callno0]);
- usleep(10);
- ast_mutex_lock(&iaxsl[callno0]);
+ DEADLOCK_AVOIDANCE(&iaxsl[callno0]);
}
}
@@ -3969,9 +3961,7 @@ static int iax2_indicate(struct ast_channel *c, int condition, const void *data,
/* We don't know the remote side's call number, yet. :( */
int count = 10;
while (count-- && pvt && !pvt->peercallno) {
- ast_mutex_unlock(&iaxsl[callno]);
- usleep(1);
- ast_mutex_lock(&iaxsl[callno]);
+ DEADLOCK_AVOIDANCE(&iaxsl[callno]);
pvt = iaxs[callno];
}
if (!pvt->peercallno) {
@@ -8284,9 +8274,7 @@ static int socket_process(struct iax2_thread *thread)
int orignative;
retryowner:
if (ast_channel_trylock(iaxs[fr->callno]->owner)) {
- ast_mutex_unlock(&iaxsl[fr->callno]);
- usleep(1);
- ast_mutex_lock(&iaxsl[fr->callno]);
+ DEADLOCK_AVOIDANCE(&iaxsl[fr->callno]);
if (iaxs[fr->callno] && iaxs[fr->callno]->owner) goto retryowner;
}
if (iaxs[fr->callno]) {
@@ -8728,9 +8716,7 @@ retryowner:
ast_verb(3, "Format for call is %s\n", ast_getformatname(iaxs[fr->callno]->owner->nativeformats));
retryowner2:
if (ast_channel_trylock(iaxs[fr->callno]->owner)) {
- ast_mutex_unlock(&iaxsl[fr->callno]);
- usleep(1);
- ast_mutex_lock(&iaxsl[fr->callno]);
+ DEADLOCK_AVOIDANCE(&iaxsl[fr->callno]);
if (iaxs[fr->callno] && iaxs[fr->callno]->owner) goto retryowner2;
}
diff --git a/channels/chan_mgcp.c b/channels/chan_mgcp.c
index 021999abdf44e37738e15162c05946b24341d690..4dc9f671ac4e09bb163292aabc3998a7f2f85ec4 100644
--- a/channels/chan_mgcp.c
+++ b/channels/chan_mgcp.c
@@ -596,9 +596,7 @@ static void mgcp_queue_frame(struct mgcp_subchannel *sub, struct ast_frame *f)
ast_channel_unlock(sub->owner);
break;
} else {
- ast_mutex_unlock(&sub->lock);
- usleep(1);
- ast_mutex_lock(&sub->lock);
+ DEADLOCK_AVOIDANCE(&sub->lock);
}
} else
break;
@@ -614,9 +612,7 @@ static void mgcp_queue_hangup(struct mgcp_subchannel *sub)
ast_channel_unlock(sub->owner);
break;
} else {
- ast_mutex_unlock(&sub->lock);
- usleep(1);
- ast_mutex_lock(&sub->lock);
+ DEADLOCK_AVOIDANCE(&sub->lock);
}
} else
break;
diff --git a/channels/chan_zap.c b/channels/chan_zap.c
index b9860f33a13d5b8f9a5cf7801d9fcd6b3718e4ff..6646ee2e1fbfdf395cb3227869906da3aa00220d 100644
--- a/channels/chan_zap.c
+++ b/channels/chan_zap.c
@@ -882,10 +882,7 @@ static inline int pri_grab(struct zt_pvt *pvt, struct zt_pri *pri)
do {
res = ast_mutex_trylock(&pri->lock);
if (res) {
- ast_mutex_unlock(&pvt->lock);
- /* Release the lock and try again */
- usleep(1);
- ast_mutex_lock(&pvt->lock);
+ DEADLOCK_AVOIDANCE(&pvt->lock);
}
} while (res);
/* Then break the poll */
@@ -976,9 +973,7 @@ static void wakeup_sub(struct zt_pvt *p, int a, void *pri)
for (;;) {
if (p->subs[a].owner) {
if (ast_channel_trylock(p->subs[a].owner)) {
- ast_mutex_unlock(&p->lock);
- usleep(1);
- ast_mutex_lock(&p->lock);
+ DEADLOCK_AVOIDANCE(&p->lock);
} else {
ast_queue_frame(p->subs[a].owner, &ast_null_frame);
ast_channel_unlock(p->subs[a].owner);
@@ -1025,9 +1020,7 @@ static void zap_queue_frame(struct zt_pvt *p, struct ast_frame *f, void *data)
for (;;) {
if (p->owner) {
if (ast_channel_trylock(p->owner)) {
- ast_mutex_unlock(&p->lock);
- usleep(1);
- ast_mutex_lock(&p->lock);
+ DEADLOCK_AVOIDANCE(&p->lock);
} else {
ast_queue_frame(p->owner, f);
ast_channel_unlock(p->owner);
@@ -3643,9 +3636,7 @@ static void zt_unlink(struct zt_pvt *slave, struct zt_pvt *master, int needlock)
ast_mutex_lock(&master->lock);
if (slave) {
while (ast_mutex_trylock(&slave->lock)) {
- ast_mutex_unlock(&master->lock);
- usleep(1);
- ast_mutex_lock(&master->lock);
+ DEADLOCK_AVOIDANCE(&master->lock);
}
}
}
@@ -10128,9 +10119,7 @@ static int pri_hangup_all(struct zt_pvt *p, struct zt_pri *pri)
for (x = 0; x < 3; x++) {
while (p->subs[x].owner && ast_channel_trylock(p->subs[x].owner)) {
redo++;
- ast_mutex_unlock(&p->lock);
- usleep(1);
- ast_mutex_lock(&p->lock);
+ DEADLOCK_AVOIDANCE(&p->lock);
}
if (p->subs[x].owner) {
ast_queue_hangup_with_cause(p->subs[x].owner, AST_CAUSE_PRE_EMPTED);
diff --git a/include/asterisk/lock.h b/include/asterisk/lock.h
index 7f8d00eb69781b9c2efbf22c596b42ce5196bb03..5a9bc252ff31df0a54be0762ab488f49fa5da8ec 100644
--- a/include/asterisk/lock.h
+++ b/include/asterisk/lock.h
@@ -220,7 +220,7 @@ static inline void __dump_backtrace(struct ast_bt *bt, int canlog)
{
char **strings;
- size_t i;
+ ssize_t i;
strings = backtrace_symbols(bt->addresses, bt->num_frames);
@@ -241,6 +241,38 @@ static inline void __dump_backtrace(struct ast_bt *bt, int canlog)
*/
void log_show_lock(void *this_lock_addr);
+/*!
+ * \brief retrieve lock info for the specified mutex
+ *
+ * this gets called during deadlock avoidance, so that the information may
+ * be preserved as to what location originally acquired the lock.
+ */
+#if !defined(LOW_MEMORY)
+int ast_find_lock_info(void *lock_addr, const char **filename, int *lineno, const char **func, const char **mutex_name);
+#else
+#define ast_find_lock_info(a,b,c,d,e) -1
+#endif
+
+/*!
+ * \brief Unlock a lock briefly
+ *
+ * used during deadlock avoidance, to preserve the original location where
+ * a lock was originally acquired.
+ */
+#define DEADLOCK_AVOIDANCE(lock) \
+ do { \
+ const char *__filename, *__func, *__mutex_name; \
+ int __lineno; \
+ int __res = ast_find_lock_info(lock, &__filename, &__lineno, &__func, &__mutex_name); \
+ ast_mutex_unlock(lock); \
+ usleep(1); \
+ if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
+ ast_mutex_lock(lock); \
+ } else { \
+ __ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
+ } \
+ } while (0)
+
static void __attribute__((constructor)) init_empty_mutex(void)
{
memset(&empty_mutex, 0, sizeof(empty_mutex));
diff --git a/main/utils.c b/main/utils.c
index dfa32eb58a4a638da454f9770da0e581c091f4ea..19fbf21e426a35ac3c3f7934f2ecc99fa089cb90 100644
--- a/main/utils.c
+++ b/main/utils.c
@@ -677,6 +677,34 @@ void ast_mark_lock_failed(void *lock_addr)
#ifdef HAVE_BKTR
void ast_remove_lock_info(void *lock_addr, struct ast_bt *bt)
#else
+int ast_find_lock_info(void *lock_addr, const char **filename, int *lineno, const char **func, const char **mutex_name)
+{
+ struct thr_lock_info *lock_info;
+ int i = 0;
+
+ if (!(lock_info = ast_threadstorage_get(&thread_lock_info, sizeof(*lock_info))))
+ return -1;
+
+ pthread_mutex_lock(&lock_info->lock);
+
+ for (i = lock_info->num_locks - 1; i >= 0; i--) {
+ if (lock_info->locks[i].lock_addr == lock_addr)
+ break;
+ }
+
+ if (i == -1) {
+ /* Lock not found :( */
+ pthread_mutex_unlock(&lock_info->lock);
+ return -1;
+ }
+
+ *filename = lock_info->locks[i].file;
+ *lineno = lock_info->locks[i].line_num;
+ *func = lock_info->locks[i].func;
+ *mutex_name = lock_info->locks[i].lock_name;
+ return 0;
+}
+
void ast_remove_lock_info(void *lock_addr)
#endif
{