Merge tag 'trace-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/ker…

…nel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix a bug caused by not cleaning up the new instance unique triggers
   when deleting an instance. It also creates a selftest that triggers
   that bug.

 - Fix the delayed optimization happening after kprobes boot up self
   tests being removed by freeing of init memory.

 - Comment kprobes on why the delay optimization is not a problem for
   removal of modules, to keep other developers from searching that
   riddle.

 - Fix another case of rcu not watching in stack trace tracing.

* tag 'trace-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Make sure RCU is watching before calling a stack trace
  kprobes: Document how optimized kprobes are removed from module unload
  selftests/ftrace: Add test to remove instance with active event triggers
  selftests/ftrace: Fix bashisms
  ftrace: Remove #ifdef from code and add clear_ftrace_function_probes() stub
  ftrace/instances: Clear function triggers when removing instances
  ftrace: Simplify glob handling in unregister_ftrace_function_probe_func()
  tracing/kprobes: Enforce kprobes teardown after testing
  tracing: Move postpone selftests to core from early_initcall

include/linux/kprobes.h

@@ -349,6 +349,9 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table,
 					     int write, void __user *buffer,
 					     size_t *length, loff_t *ppos);
 #endif
+extern void wait_for_kprobe_optimizer(void);
+#else
+static inline void wait_for_kprobe_optimizer(void) { }
 #endif /* CONFIG_OPTPROBES */
 #ifdef CONFIG_KPROBES_ON_FTRACE
 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,

kernel/kprobes.c

@@ -595,7 +595,7 @@ static void kprobe_optimizer(struct work_struct *work)
 }
 
 /* Wait for completing optimization and unoptimization */
-static void wait_for_kprobe_optimizer(void)
+void wait_for_kprobe_optimizer(void)
 {
 	mutex_lock(&kprobe_mutex);
 
@@ -2183,6 +2183,12 @@ static int kprobes_module_callback(struct notifier_block *nb,
 				 * The vaddr this probe is installed will soon
 				 * be vfreed buy not synced to disk. Hence,
 				 * disarming the breakpoint isn't needed.
+				 *
+				 * Note, this will also move any optimized probes
+				 * that are pending to be removed from their
+				 * corresponding lists to the freeing_list and
+				 * will not be touched by the delayed
+				 * kprobe_optimizer work handler.
 				 */
 				kill_kprobe(p);
 			}

kernel/trace/ftrace.c

@@ -4144,9 +4144,9 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 	int i, ret = -ENODEV;
 	int size;
 
-	if (glob && (strcmp(glob, "*") == 0 || !strlen(glob)))
+	if (!glob || !strlen(glob) || !strcmp(glob, "*"))
 		func_g.search = NULL;
-	else if (glob) {
+	else {
 		int not;
 
 		func_g.type = filter_parse_regex(glob, strlen(glob),
@@ -4256,6 +4256,14 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 	return ret;
 }
 
+void clear_ftrace_function_probes(struct trace_array *tr)
+{
+	struct ftrace_func_probe *probe, *n;
+
+	list_for_each_entry_safe(probe, n, &tr->func_probes, list)
+		unregister_ftrace_function_probe_func(NULL, tr, probe->probe_ops);
+}
+
 static LIST_HEAD(ftrace_commands);
 static DEFINE_MUTEX(ftrace_cmd_mutex);
 

kernel/trace/trace.c

@@ -1558,7 +1558,7 @@ static __init int init_trace_selftests(void)
 
 	return 0;
 }
-early_initcall(init_trace_selftests);
+core_initcall(init_trace_selftests);
 #else
 static inline int run_tracer_selftest(struct tracer *type)
 {
@@ -2568,7 +2568,36 @@ static inline void ftrace_trace_stack(struct trace_array *tr,
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 		   int pc)
 {
-	__ftrace_trace_stack(tr->trace_buffer.buffer, flags, skip, pc, NULL);
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
+
+	if (rcu_is_watching()) {
+		__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
+		return;
+	}
+
+	/*
+	 * When an NMI triggers, RCU is enabled via rcu_nmi_enter(),
+	 * but if the above rcu_is_watching() failed, then the NMI
+	 * triggered someplace critical, and rcu_irq_enter() should
+	 * not be called from NMI.
+	 */
+	if (unlikely(in_nmi()))
+		return;
+
+	/*
+	 * It is possible that a function is being traced in a
+	 * location that RCU is not watching. A call to
+	 * rcu_irq_enter() will make sure that it is, but there's
+	 * a few internal rcu functions that could be traced
+	 * where that wont work either. In those cases, we just
+	 * do nothing.
+	 */
+	if (unlikely(rcu_irq_enter_disabled()))
+		return;
+
+	rcu_irq_enter_irqson();
+	__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
+	rcu_irq_exit_irqson();
 }
 
 /**
@@ -7550,6 +7579,7 @@ static int instance_rmdir(const char *name)
 	}
 
 	tracing_set_nop(tr);
+	clear_ftrace_function_probes(tr);
 	event_trace_del_tracer(tr);
 	ftrace_clear_pids(tr);
 	ftrace_destroy_function_files(tr);

kernel/trace/trace.h

@@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
 extern int
 unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 				      struct ftrace_probe_ops *ops);
+extern void clear_ftrace_function_probes(struct trace_array *tr);
 
 int register_ftrace_command(struct ftrace_func_command *cmd);
 int unregister_ftrace_command(struct ftrace_func_command *cmd);
@@ -998,6 +999,10 @@ static inline __init int unregister_ftrace_command(char *cmd_name)
 {
 	return -EINVAL;
 }
+static inline void clear_ftrace_function_probes(struct trace_array *tr)
+{
+}
+
 /*
  * The ops parameter passed in is usually undefined.
  * This must be a macro.

kernel/trace/trace_kprobe.c

@@ -1535,6 +1535,11 @@ static __init int kprobe_trace_self_tests_init(void)
 
 end:
 	release_all_trace_kprobes();
+	/*
+	 * Wait for the optimizer work to finish. Otherwise it might fiddle
+	 * with probes in already freed __init text.
+	 */
+	wait_for_kprobe_optimizer();
 	if (warn)
 		pr_cont("NG: Some tests are failed. Please check them.\n");
 	else

tools/testing/selftests/ftrace/ftracetest

@@ -58,7 +58,7 @@ parse_opts() { # opts
     ;;
     --verbose|-v|-vv)
       VERBOSE=$((VERBOSE + 1))
-      [ $1 == '-vv' ] && VERBOSE=$((VERBOSE + 1))
+      [ $1 = '-vv' ] && VERBOSE=$((VERBOSE + 1))
       shift 1
     ;;
     --debug|-d)

tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc

@@ -48,7 +48,7 @@ test_event_enabled() {
     e=`cat $EVENT_ENABLE`
     if [ "$e" != $val ]; then
 	echo "Expected $val but found $e"
-	exit -1
+	exit 1
     fi
 }
 

tools/testing/selftests/ftrace/test.d/functions

@@ -34,10 +34,10 @@ reset_ftrace_filter() { # reset all triggers in set_ftrace_filter
     echo > set_ftrace_filter
     grep -v '^#' set_ftrace_filter | while read t; do
 	tr=`echo $t | cut -d: -f2`
-	if [ "$tr" == "" ]; then
+	if [ "$tr" = "" ]; then
 	    continue
 	fi
-	if [ $tr == "enable_event" -o $tr == "disable_event" ]; then
+	if [ $tr = "enable_event" -o $tr = "disable_event" ]; then
 	    tr=`echo $t | cut -d: -f1-4`
 	    limit=`echo $t | cut -d: -f5`
 	else

tools/testing/selftests/ftrace/test.d/instances/instance-event.tc

@@ -75,9 +75,13 @@ rmdir foo
 if [ -d foo ]; then
         fail "foo still exists"
 fi
-exit 0
-
 
+mkdir foo
+echo "schedule:enable_event:sched:sched_switch" > foo/set_ftrace_filter
+rmdir foo
+if [ -d foo ]; then
+        fail "foo still exists"
+fi
 
 
 instance_slam() {