Re-initialize logmsgs mutex upon logger initialization to prevent lock errors

Similar to the patch that moved the fork earlier in the startup sequence to
prevent mutex errors in the recursive mutex surrounding the read/write thread
registration lock, this patch re-initializes the logmsgs mutex.  Part of the
start up sequence before forking the process into the background includes
reading asterisk.conf; this has to occur prior to the call to daemon in order
to read startup parameters.  When reading in a conf file, log statements can
be generated.  Since this can't be avoided, the mutex instead is
re-initialized to ensure a reset of any thread tracking information.

This patch also includes some additional debugging to catch errors when
locking or unlocking the recursive mutex that surrounds locks when the
DEBUG_THREADS build option is enabled.  DO_CRASH or THREAD_CRASH will
cause an abort() if a mutex error is detected.

(issue ASTERISK-19463)
Reported by: mjordan
Tesetd by: mjordan
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Merged revisions 376586 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 376587 from http://svn.asterisk.org/svn/asterisk/branches/10
........

Merged revisions 376588 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@376589 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/lock.h

@@ -428,12 +428,24 @@ int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, in
 
 static inline void ast_reentrancy_lock(struct ast_lock_track *lt)
 {
-	pthread_mutex_lock(&lt->reentr_mutex);
+	int res;
+	if ((res = pthread_mutex_lock(&lt->reentr_mutex))) {
+		fprintf(stderr, "ast_reentrancy_lock failed: '%s' (%d)\n", strerror(res), res);
+#if defined(DO_CRASH) || defined(THREAD_CRASH)
+		abort();
+#endif
+	}
 }
 
 static inline void ast_reentrancy_unlock(struct ast_lock_track *lt)
 {
-	pthread_mutex_unlock(&lt->reentr_mutex);
+	int res;
+	if ((res = pthread_mutex_unlock(&lt->reentr_mutex))) {
+		fprintf(stderr, "ast_reentrancy_unlock failed: '%s' (%d)\n", strerror(res), res);
+#if defined(DO_CRASH) || defined(THREAD_CRASH)
+		abort();
+#endif
+	}
 }
 
 static inline void ast_reentrancy_init(struct ast_lock_track **plt)

main/lock.c

@@ -51,8 +51,8 @@ int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, con
 	int res;
 	pthread_mutexattr_t  attr;
 
-	t->track = NULL;
 #ifdef DEBUG_THREADS
+	t->track = NULL;
 #if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
 	if ((t->mutex) != ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
 /*

main/logger.c

@@ -1226,8 +1226,17 @@ int init_logger(void)
 	/* auto rotate if sig SIGXFSZ comes a-knockin */
 	sigaction(SIGXFSZ, &handle_SIGXFSZ, NULL);
 
-	/* start logger thread */
+	/* Re-initialize the logmsgs mutex.  The recursive mutex can be accessed prior
+ 	 * to Asterisk being forked into the background, which can cause the thread
+ 	 * ID tracked by the underlying pthread mutex to be different than the ID of
+ 	 * the thread that unlocks the mutex.  Since init_logger is called after the
+ 	 * fork, it is safe to initialize the mutex here for future accesses.
+ 	 */
+	ast_mutex_destroy(&logmsgs.lock);
+	ast_mutex_init(&logmsgs.lock);
 	ast_cond_init(&logcond, NULL);
+
+	/* start logger thread */
 	if (ast_pthread_create(&logthread, NULL, logger_thread, NULL) < 0) {
 		ast_cond_destroy(&logcond);
 		return -1;