tracing: Update event filters for multibuffer

The trace event filters are still tied to event calls rather than
event files, which means you don't get what you'd expect when using
filters in the multibuffer case:

Before:

  # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # mkdir /sys/kernel/debug/tracing/instances/test1
  # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 2048
  # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  bytes_alloc > 2048

Setting the filter in tracing/instances/test1/events shouldn't affect
the same event in tracing/events as it does above.

After:

  # echo 'bytes_alloc > 8192' > /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # mkdir /sys/kernel/debug/tracing/instances/test1
  # echo 'bytes_alloc > 2048' > /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/filter
  bytes_alloc > 8192
  # cat /sys/kernel/debug/tracing/instances/test1/events/kmem/kmalloc/filter
  bytes_alloc > 2048

We'd like to just move the filter directly from ftrace_event_call to
ftrace_event_file, but there are a couple cases that don't yet have
multibuffer support and therefore have to continue using the current
event_call-based filters.  For those cases, a new USE_CALL_FILTER bit
is added to the event_call flags, whose main purpose is to keep the
old behavior for those cases until they can be updated with
multibuffer support; at that point, the USE_CALL_FILTER flag (and the
new associated call_filter_check_discard() function) can go away.

The multibuffer support also made filter_current_check_discard()
redundant, so this change removes that function as well and replaces
it with filter_check_discard() (or call_filter_check_discard() as
appropriate).

Link: http://lkml.kernel.org/r/f16e9ce4270c62f46b2e966119225e1c3cca7e60.1382620672.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 179 insertions, 39 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 97daa8cf958d..2468f56dc5db 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -637,10 +637,18 @@ static void append_filter_err(struct filter_parse_state *ps,
 	free_page((unsigned long) buf);
 }
 
+static inline struct event_filter *event_filter(struct ftrace_event_file *file)
+{
+	if (file->event_call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		return file->event_call->filter;
+	else
+		return file->filter;
+}
+
 /* caller must hold event_mutex */
-void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
+void print_event_filter(struct ftrace_event_file *file, struct trace_seq *s)
 {
-	struct event_filter *filter = call->filter;
+	struct event_filter *filter = event_filter(file);
 
 	if (filter && filter->filter_string)
 		trace_seq_printf(s, "%s\n", filter->filter_string);
@@ -766,11 +774,21 @@ static void __free_preds(struct event_filter *filter)
 	filter->n_preds = 0;
 }
 
-static void filter_disable(struct ftrace_event_call *call)
+static void call_filter_disable(struct ftrace_event_call *call)
 {
 	call->flags &= ~TRACE_EVENT_FL_FILTERED;
 }
 
+static void filter_disable(struct ftrace_event_file *file)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		call_filter_disable(call);
+	else
+		file->flags &= ~FTRACE_EVENT_FL_FILTERED;
+}
+
 static void __free_filter(struct event_filter *filter)
 {
 	if (!filter)
@@ -781,16 +799,30 @@ static void __free_filter(struct event_filter *filter)
 	kfree(filter);
 }
 
+void destroy_call_preds(struct ftrace_event_call *call)
+{
+	__free_filter(call->filter);
+	call->filter = NULL;
+}
+
+static void destroy_file_preds(struct ftrace_event_file *file)
+{
+	__free_filter(file->filter);
+	file->filter = NULL;
+}
+
 /*
- * Called when destroying the ftrace_event_call.
- * The call is being freed, so we do not need to worry about
- * the call being currently used. This is for module code removing
+ * Called when destroying the ftrace_event_file.
+ * The file is being freed, so we do not need to worry about
+ * the file being currently used. This is for module code removing
  * the tracepoints from within it.
  */
-void destroy_preds(struct ftrace_event_call *call)
+void destroy_preds(struct ftrace_event_file *file)
 {
-	__free_filter(call->filter);
-	call->filter = NULL;
+	if (file->event_call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		destroy_call_preds(file->event_call);
+	else
+		destroy_file_preds(file);
 }
 
 static struct event_filter *__alloc_filter(void)
@@ -825,28 +857,56 @@ static int __alloc_preds(struct event_filter *filter, int n_preds)
 	return 0;
 }
 
-static void filter_free_subsystem_preds(struct event_subsystem *system)
+static inline void __remove_filter(struct ftrace_event_file *file)
 {
+	struct ftrace_event_call *call = file->event_call;
+
+	filter_disable(file);
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		remove_filter_string(call->filter);
+	else
+		remove_filter_string(file->filter);
+}
+
+static void filter_free_subsystem_preds(struct event_subsystem *system,
+					struct trace_array *tr)
+{
+	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
 
-	list_for_each_entry(call, &ftrace_events, list) {
+	list_for_each_entry(file, &tr->events, list) {
+		call = file->event_call;
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;
 
-		filter_disable(call);
-		remove_filter_string(call->filter);
+		__remove_filter(file);
 	}
 }
 
-static void filter_free_subsystem_filters(struct event_subsystem *system)
+static inline void __free_subsystem_filter(struct ftrace_event_file *file)
 {
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER) {
+		__free_filter(call->filter);
+		call->filter = NULL;
+	} else {
+		__free_filter(file->filter);
+		file->filter = NULL;
+	}
+}
+
+static void filter_free_subsystem_filters(struct event_subsystem *system,
+					  struct trace_array *tr)
+{
+	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
 
-	list_for_each_entry(call, &ftrace_events, list) {
+	list_for_each_entry(file, &tr->events, list) {
+		call = file->event_call;
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;
-		__free_filter(call->filter);
-		call->filter = NULL;
+		__free_subsystem_filter(file);
 	}
 }
 
@@ -1617,15 +1677,85 @@ fail:
 	return err;
 }
 
+static inline void event_set_filtered_flag(struct ftrace_event_file *file)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		call->flags |= TRACE_EVENT_FL_FILTERED;
+	else
+		file->flags |= FTRACE_EVENT_FL_FILTERED;
+}
+
+static inline void event_set_filter(struct ftrace_event_file *file,
+				    struct event_filter *filter)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		rcu_assign_pointer(call->filter, filter);
+	else
+		rcu_assign_pointer(file->filter, filter);
+}
+
+static inline void event_clear_filter(struct ftrace_event_file *file)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		RCU_INIT_POINTER(call->filter, NULL);
+	else
+		RCU_INIT_POINTER(file->filter, NULL);
+}
+
+static inline void
+event_set_no_set_filter_flag(struct ftrace_event_file *file)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		call->flags |= TRACE_EVENT_FL_NO_SET_FILTER;
+	else
+		file->flags |= FTRACE_EVENT_FL_NO_SET_FILTER;
+}
+
+static inline void
+event_clear_no_set_filter_flag(struct ftrace_event_file *file)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
+		call->flags &= ~TRACE_EVENT_FL_NO_SET_FILTER;
+	else
+		file->flags &= ~FTRACE_EVENT_FL_NO_SET_FILTER;
+}
+
+static inline bool
+event_no_set_filter_flag(struct ftrace_event_file *file)
+{
+	struct ftrace_event_call *call = file->event_call;
+
+	if (file->flags & FTRACE_EVENT_FL_NO_SET_FILTER)
+		return true;
+
+	if ((call->flags & TRACE_EVENT_FL_USE_CALL_FILTER) &&
+	    (call->flags & TRACE_EVENT_FL_NO_SET_FILTER))
+		return true;
+
+	return false;
+}
+
 struct filter_list {
 	struct list_head	list;
 	struct event_filter	*filter;
 };
 
 static int replace_system_preds(struct event_subsystem *system,
+				struct trace_array *tr,
 				struct filter_parse_state *ps,
 				char *filter_string)
 {
+	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
 	struct filter_list *filter_item;
 	struct filter_list *tmp;
@@ -1633,8 +1763,8 @@ static int replace_system_preds(struct event_subsystem *system,
 	bool fail = true;
 	int err;
 
-	list_for_each_entry(call, &ftrace_events, list) {
-
+	list_for_each_entry(file, &tr->events, list) {
+		call = file->event_call;
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;
 
@@ -1644,18 +1774,20 @@ static int replace_system_preds(struct event_subsystem *system,
 		 */
 		err = replace_preds(call, NULL, ps, filter_string, true);
 		if (err)
-			call->flags |= TRACE_EVENT_FL_NO_SET_FILTER;
+			event_set_no_set_filter_flag(file);
 		else
-			call->flags &= ~TRACE_EVENT_FL_NO_SET_FILTER;
+			event_clear_no_set_filter_flag(file);
 	}
 
-	list_for_each_entry(call, &ftrace_events, list) {
+	list_for_each_entry(file, &tr->events, list) {
 		struct event_filter *filter;
 
+		call = file->event_call;
+
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;
 
-		if (call->flags & TRACE_EVENT_FL_NO_SET_FILTER)
+		if (event_no_set_filter_flag(file))
 			continue;
 
 		filter_item = kzalloc(sizeof(*filter_item), GFP_KERNEL);
@@ -1676,17 +1808,17 @@ static int replace_system_preds(struct event_subsystem *system,
 
 		err = replace_preds(call, filter, ps, filter_string, false);
 		if (err) {
-			filter_disable(call);
+			filter_disable(file);
 			parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
 			append_filter_err(ps, filter);
 		} else
-			call->flags |= TRACE_EVENT_FL_FILTERED;
+			event_set_filtered_flag(file);
 		/*
 		 * Regardless of if this returned an error, we still
 		 * replace the filter for the call.
 		 */
-		filter = call->filter;
-		rcu_assign_pointer(call->filter, filter_item->filter);
+		filter = event_filter(file);
+		event_set_filter(file, filter_item->filter);
 		filter_item->filter = filter;
 
 		fail = false;
@@ -1816,6 +1948,7 @@ static int create_filter(struct ftrace_event_call *call,
  * and always remembers @filter_str.
  */
 static int create_system_filter(struct event_subsystem *system,
+				struct trace_array *tr,
 				char *filter_str, struct event_filter **filterp)
 {
 	struct event_filter *filter = NULL;
@@ -1824,7 +1957,7 @@ static int create_system_filter(struct event_subsystem *system,
 
 	err = create_filter_start(filter_str, true, &ps, &filter);
 	if (!err) {
-		err = replace_system_preds(system, ps, filter_str);
+		err = replace_system_preds(system, tr, ps, filter_str);
 		if (!err) {
 			/* System filters just show a default message */
 			kfree(filter->filter_string);
@@ -1840,20 +1973,25 @@ static int create_system_filter(struct event_subsystem *system,
 }
 
 /* caller must hold event_mutex */
-int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
+int apply_event_filter(struct ftrace_event_file *file, char *filter_string)
 {
+	struct ftrace_event_call *call = file->event_call;
 	struct event_filter *filter;
 	int err;
 
 	if (!strcmp(strstrip(filter_string), "0")) {
-		filter_disable(call);
-		filter = call->filter;
+		filter_disable(file);
+		filter = event_filter(file);
+
 		if (!filter)
 			return 0;
-		RCU_INIT_POINTER(call->filter, NULL);
+
+		event_clear_filter(file);
+
 		/* Make sure the filter is not being used */
 		synchronize_sched();
 		__free_filter(filter);
+
 		return 0;
 	}
 
@@ -1866,14 +2004,15 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
 	 * string
 	 */
 	if (filter) {
-		struct event_filter *tmp = call->filter;
+		struct event_filter *tmp;
 
+		tmp = event_filter(file);
 		if (!err)
-			call->flags |= TRACE_EVENT_FL_FILTERED;
+			event_set_filtered_flag(file);
 		else
-			filter_disable(call);
+			filter_disable(file);
 
-		rcu_assign_pointer(call->filter, filter);
+		event_set_filter(file, filter);
 
 		if (tmp) {
 			/* Make sure the call is done with the filter */
@@ -1889,6 +2028,7 @@ int apply_subsystem_event_filter(struct ftrace_subsystem_dir *dir,
 				 char *filter_string)
 {
 	struct event_subsystem *system = dir->subsystem;
+	struct trace_array *tr = dir->tr;
 	struct event_filter *filter;
 	int err = 0;
 
@@ -1901,18 +2041,18 @@ int apply_subsystem_event_filter(struct ftrace_subsystem_dir *dir,
 	}
 
 	if (!strcmp(strstrip(filter_string), "0")) {
-		filter_free_subsystem_preds(system);
+		filter_free_subsystem_preds(system, tr);
 		remove_filter_string(system->filter);
 		filter = system->filter;
 		system->filter = NULL;
 		/* Ensure all filters are no longer used */
 		synchronize_sched();
-		filter_free_subsystem_filters(system);
+		filter_free_subsystem_filters(system, tr);
 		__free_filter(filter);
 		goto out_unlock;
 	}
 
-	err = create_system_filter(system, filter_string, &filter);
+	err = create_system_filter(system, tr, filter_string, &filter);
 	if (filter) {
 		/*
 		 * No event actually uses the system filter