Merged revisions 273793 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r273793 | tilghman | 2010-07-02 16:36:39 -0500 (Fri, 02 Jul 2010) | 9 lines
  
  Have the DEADLOCK_AVOIDANCE macro warn when an unlock fails, to help catch potentially large software bugs.
  
  (closes issue #17407)
   Reported by: pdf
   Patches: 
         20100527__issue17407.diff.txt uploaded by tilghman (license 14)
   
  Review: https://reviewboard.asterisk.org/r/751/
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@273830 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_agent.c

@@ -715,7 +715,12 @@ static int agent_indicate(struct ast_channel *ast, int condition, const void *da
 	ast_mutex_lock(&p->lock);
 	if (p->chan && !ast_check_hangup(p->chan)) {
 		while (ast_channel_trylock(p->chan)) {
-			ast_channel_unlock(ast);
+			int res;
+			if ((res = ast_channel_unlock(ast))) {
+				ast_log(LOG_ERROR, "chan_agent bug! Channel was not locked upon entry to agent_indicate: %s\n", strerror(res));
+				ast_mutex_unlock(&p->lock);
+				return -1;
+			}
 			usleep(1);
 			ast_channel_lock(ast);
 		}

channels/chan_h323.c

@@ -306,7 +306,7 @@ static int oh323_simulate_dtmf_end(const void *data)
 	if (pvt) {
 		ast_mutex_lock(&pvt->lock);
 		/* Don't hold pvt lock while trying to lock the channel */
-		while(pvt->owner && ast_channel_trylock(pvt->owner)) {
+		while (pvt->owner && ast_channel_trylock(pvt->owner)) {
 			DEADLOCK_AVOIDANCE(&pvt->lock);
 		}
 

channels/chan_local.c

@@ -250,7 +250,11 @@ static int local_queue_frame(struct local_pvt *p, int isoutbound, struct ast_fra
 
 	/* Ensure that we have both channels locked */
 	while (other && ast_channel_trylock(other)) {
-		ast_mutex_unlock(&p->lock);
+		int res;
+		if ((res = ast_mutex_unlock(&p->lock))) {
+			ast_log(LOG_ERROR, "chan_local bug! '&p->lock' was not locked when entering local_queue_frame! (%s)\n", strerror(res));
+			return -1;
+		}
 		if (us && us_locked) {
 			do {
 				CHANNEL_DEADLOCK_AVOIDANCE(us);

include/asterisk/lock.h

@@ -60,6 +60,7 @@
 #endif
 
 #include "asterisk/logger.h"
+#include "asterisk/compiler.h"
 
 #define AST_PTHREADT_NULL (pthread_t) -1
 #define AST_PTHREADT_STOP (pthread_t) -2
@@ -339,13 +340,21 @@ int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, in
 		char __filename[80], __func[80], __mutex_name[80]; \
 		int __lineno; \
 		int __res = ast_find_lock_info(ao2_object_get_lockaddr(chan), __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
-		ast_channel_unlock(chan); \
+		int __res2 = ast_channel_unlock(chan); \
 		usleep(1); \
 		if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
+			if (__res2) { \
+				ast_log(LOG_WARNING, "Could not unlock channel '%s': %s and no lock info found!  I will NOT try to relock.\n", #chan, strerror(__res2)); \
+			} else { \
 				ast_channel_lock(chan); \
+			} \
+		} else { \
+			if (__res2) { \
+				ast_log(LOG_WARNING, "Could not unlock channel '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #chan, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
 			} else { \
 				__ao2_lock(chan, __filename, __func, __lineno, __mutex_name); \
 			} \
+		} \
 	} while (0)
 
 #define DEADLOCK_AVOIDANCE(lock) \
@@ -353,12 +362,20 @@ int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, in
 		char __filename[80], __func[80], __mutex_name[80]; \
 		int __lineno; \
 		int __res = ast_find_lock_info(lock, __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
-		ast_mutex_unlock(lock); \
+		int __res2 = ast_mutex_unlock(lock); \
 		usleep(1); \
 		if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
+			if (__res2 == 0) { \
 				ast_mutex_lock(lock); \
 			} else { \
+				ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s and no lock info found!  I will NOT try to relock.\n", #lock, strerror(__res2)); \
+			} \
+		} else { \
+			if (__res2 == 0) { \
 				__ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
+			} else { \
+				ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #lock, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
+			} \
 		} \
 	} while (0)
 
@@ -379,7 +396,7 @@ int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, in
 		char __filename[80], __func[80], __mutex_name[80]; \
 		int __lineno; \
 		int __res = ast_find_lock_info(lock, __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
-		ast_mutex_unlock(lock);
+		int __res2 = ast_mutex_unlock(lock);
 
 /*!
  * \brief Deadlock avoidance lock
@@ -395,10 +412,18 @@ int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, in
  */
 #define DLA_LOCK(lock) \
 		if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
+			if (__res2) { \
+				ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s and no lock info found!  I will NOT try to relock.\n", #lock, strerror(__res2)); \
+			} else { \
 				ast_mutex_lock(lock); \
+			} \
+		} else { \
+			if (__res2) { \
+				ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #lock, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
 			} else { \
 				__ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
 			} \
+		} \
 	} while (0)
 
 static inline void ast_reentrancy_lock(struct ast_lock_track *lt)
@@ -447,9 +472,15 @@ static inline void delete_reentrancy_cs(struct ast_lock_track *lt)
 	ast_channel_lock(chan);
 
 #define	DEADLOCK_AVOIDANCE(lock) \
-	ast_mutex_unlock(lock); \
+	do { \
+		int __res; \
+		if (!(__res = ast_mutex_unlock(lock))) { \
 			usleep(1); \
-	ast_mutex_lock(lock);
+			ast_mutex_lock(lock); \
+		} else { \
+			ast_log(LOG_WARNING, "Failed to unlock mutex '%s' (%s).  I will NOT try to relock. {{{ THIS IS A BUG. }}}\n", #lock, strerror(__res)); \
+		} \
+	} while (0)
 
 #define DLA_UNLOCK(lock) ast_mutex_unlock(lock)