SWPTP-1532: add programmatic backtrace on dead thread access

Makefile

@@ -70,6 +70,11 @@ STATIC_LIBRARIES :=
 TARGETS :=
 MKDIR = mkdir -p
 
+ifdef DEBUG
+# Enable symbolic backtraces
+LDFLAGS += -rdynamic
+endif
+
 # Build directory
 BUILD_DIR = build
 

src/include/sfptpd_misc.h

@@ -202,4 +202,8 @@ int sfptpd_ht_get_num_entries(struct sfptpd_hash_table *table);
  */
 int sfptpd_find_running_programs(struct sfptpd_prog *others);
 
+/** Log a backtrace of the current thread.
+ */
+void sfptpd_debug_backtrace(void);
+
 #endif /* _SFPTPD_MISC_H */

src/sfptpd_misc.c

@@ -21,6 +21,7 @@
 #include <fts.h>
 #include <fnmatch.h>
 #include <linux/taskstats.h>
+#include <execinfo.h>
 
 #include "sfptpd_misc.h"
 #include "sfptpd_logging.h"
@@ -191,6 +192,29 @@ void sfptpd_local_strftime(char *s, size_t max, const char *format, const sfptpd
 }
 
 
+void sfptpd_debug_backtrace(void)
+{
+#define BACKTRACE_SIZE 128
+	void **buffer = malloc(BACKTRACE_SIZE * sizeof(void *));
+	char **strings;
+	int len;
+
+	if (!buffer)
+		return;
+
+	len = backtrace(buffer, BACKTRACE_SIZE);
+	strings = backtrace_symbols(buffer, len);
+	if (strings) {
+		while(--len >= 1) {
+			TRACE_L3("frame %d: %s\n", len, strings[len]);
+		}
+		free(strings);
+	}
+
+	free(buffer);
+}
+
+
 /****************************************************************************
  * Hash table functions
  ****************************************************************************/

src/sfptpd_thread.c

@@ -1175,7 +1175,7 @@ int sfptpd_msg_send_wait(sfptpd_msg_hdr_t *msg,
 
 	rc = queue_send(&recipient->queue_general, msg);
 
-	SFPTPD_MSG_TRACE("msg %p send %d reply %d wait rc %d 0x%x\n", msg,
+	SFPTPD_MSG_TRACE("msg %p send %d reply %d wait rc %d id 0x%x\n", msg,
 			recipient->queue_general.pipe.fds[PIPE_WRITE_IDX],
 			reply_fd, rc, id);
 
@@ -1996,6 +1996,9 @@ struct sfptpd_thread *sfptpd_thread_self(void)
 {
 	struct sfptpd_thread *self = thread_self();
 
+	if (self == NULL)
+		sfptpd_debug_backtrace();
+
 	assert(self != NULL);
 	return self;
 }