This fixes 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 rcu isn't watching in stack trace tracing.
 
 Naveen N. Rao (4):
       ftrace: Simplify glob handling in unregister_ftrace_function_probe_func()
       ftrace/instances: Clear function triggers when removing instances
       selftests/ftrace: Fix bashisms
       selftests/ftrace: Add test to remove instance with active event triggers
 
 Steven Rostedt (1):
       tracing: Move postpone selftests to core from early_initcall
 
 Steven Rostedt (VMware) (3):
       ftrace: Remove #ifdef from code and add clear_ftrace_function_probes() stub
       kprobes: Document how optimized kprobes are removed from module unload
       tracing: Make sure RCU is watching before calling a stack trace
 
 Thomas Gleixner (1):
       tracing/kprobes: Enforce kprobes teardown after testing
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Merge tag 'trace-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/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() {