- Extend the KDB interface to add a per-debugger callback to print a

  backtrace for an arbitrary thread (rather than the calling thread).
  A kdb_backtrace_thread() wrapper function uses the configured debugger
  if possible, otherwise it falls back to using stack(9) if that is
  available.
- Replace a direct call to db_trace_thread() in propagate_priority()
  with a call to kdb_backtrace_thread() instead.

MFC after:	1 week

1 files changed, 26 insertions, 1 deletions

diff --git a/sys/kern/subr_kdb.c b/sys/kern/subr_kdb.c
index 9ca34b1..59d6258 100644
--- a/sys/kern/subr_kdb.c
+++ b/sys/kern/subr_kdb.c
@@ -73,7 +73,7 @@ struct trapframe *kdb_frame = NULL;
 static int	kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
 static int	kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
 
-KDB_BACKEND(null, NULL, NULL, NULL);
+KDB_BACKEND(null, NULL, NULL, NULL, NULL);
 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
 
 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
@@ -376,6 +376,7 @@ kdb_backtrace(void)
 		struct stack st;
 
 		printf("KDB: stack backtrace:\n");
+		stack_zero(&st);
 		stack_save(&st);
 		stack_print_ddb(&st);
 	}
@@ -383,6 +384,30 @@ kdb_backtrace(void)
 }
 
 /*
+ * Similar to kdb_backtrace() except that it prints a backtrace of an
+ * arbitrary thread rather than the calling thread.
+ */
+void
+kdb_backtrace_thread(struct thread *td)
+{
+
+	if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
+		printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
+		kdb_dbbe->dbbe_trace_thread(td);
+	}
+#ifdef STACK
+	else {
+		struct stack st;
+
+		printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
+		stack_zero(&st);
+		stack_save_td(&st, td);
+		stack_print_ddb(&st);
+	}
+#endif
+}
+
+/*
  * Set/change the current backend.
  */