Commit 1f9963cb authored by Li Zefan's avatar Li Zefan Committed by Steven Rostedt
Browse files

tracing/filters: improve subsystem filter 



Currently a subsystem filter should be applicable to all events
under the subsystem, and if it failed, all the event filters
will be cleared. Those behaviors make subsys filter much less
useful:

  # echo 'vec == 1' > irq/softirq_entry/filter
  # echo 'irq == 5' > irq/filter
  bash: echo: write error: Invalid argument
  # cat irq/softirq_entry/filter
  none

I'd expect it set the filter for irq_handler_entry/exit, and
not touch softirq_entry/exit.

The basic idea is, try to see if the filter can be applied
to which events, and then just apply to the those events:

  # echo 'vec == 1' > softirq_entry/filter
  # echo 'irq == 5' > filter
  # cat irq_handler_entry/filter
  irq == 5
  # cat softirq_entry/filter
  vec == 1

Changelog for v2:
- do some cleanups to address Frederic's comments.

Inspired-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A63D485.7030703@cn.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent ff4e9da2

include/linux/ftrace_event.h

+3 −1
Original line number Diff line number Diff line
@@ -101,6 +101,8 @@ void trace_current_buffer_discard_commit(struct ring_buffer_event *event); 


void tracing_record_cmdline(struct task_struct *tsk);



struct event_filter;



struct ftrace_event_call {

	struct list_head	list;

	char			*name;
@@ -116,7 +118,7 @@ struct ftrace_event_call { 
	int			(*define_fields)(void);

	struct list_head	fields;

	int			filter_active;

	void			*filter;

	struct event_filter	*filter;

	void			*mod;



#ifdef CONFIG_EVENT_PROFILE

kernel/trace/trace.h

+2 −1
Original line number Diff line number Diff line
@@ -750,13 +750,14 @@ struct event_filter { 
	int			n_preds;

	struct filter_pred	**preds;

	char			*filter_string;

	bool			no_reset;

};



struct event_subsystem {

	struct list_head	list;

	const char		*name;

	struct dentry		*entry;

	void			*filter;

	struct event_filter	*filter;

	int			nr_events;

};

kernel/trace/trace_events_filter.c

+82 −42
Original line number Diff line number Diff line
@@ -420,7 +420,14 @@ oom: 
}

EXPORT_SYMBOL_GPL(init_preds);



static void filter_free_subsystem_preds(struct event_subsystem *system)

enum {

	FILTER_DISABLE_ALL,

	FILTER_INIT_NO_RESET,

	FILTER_SKIP_NO_RESET,

};



static void filter_free_subsystem_preds(struct event_subsystem *system,

					int flag)

{

	struct ftrace_event_call *call;
@@ -428,6 +435,14 @@ static void filter_free_subsystem_preds(struct event_subsystem *system) 
		if (!call->define_fields)

			continue;



		if (flag == FILTER_INIT_NO_RESET) {

			call->filter->no_reset = false;

			continue;

		}



		if (flag == FILTER_SKIP_NO_RESET && call->filter->no_reset)

			continue;



		if (!strcmp(call->system, system->name)) {

			filter_disable_preds(call);

			remove_filter_string(call->filter);
@@ -529,7 +544,8 @@ static filter_pred_fn_t select_comparison_fn(int op, int field_size, 


static int filter_add_pred(struct filter_parse_state *ps,

			   struct ftrace_event_call *call,

			   struct filter_pred *pred)

			   struct filter_pred *pred,

			   bool dry_run)

{

	struct ftrace_event_field *field;

	filter_pred_fn_t fn;
@@ -541,10 +557,12 @@ static int filter_add_pred(struct filter_parse_state *ps, 


	if (pred->op == OP_AND) {

		pred->pop_n = 2;

		return filter_add_pred_fn(ps, call, pred, filter_pred_and);

		fn = filter_pred_and;

		goto add_pred_fn;

	} else if (pred->op == OP_OR) {

		pred->pop_n = 2;

		return filter_add_pred_fn(ps, call, pred, filter_pred_or);

		fn = filter_pred_or;

		goto add_pred_fn;

	}



	field = find_event_field(call, pred->field_name);
@@ -567,9 +585,6 @@ static int filter_add_pred(struct filter_parse_state *ps, 
		else

			fn = filter_pred_strloc;

		pred->str_len = field->size;

		if (pred->op == OP_NE)

			pred->not = 1;

		return filter_add_pred_fn(ps, call, pred, fn);

	} else {

		if (field->is_signed)

			ret = strict_strtoll(pred->str_val, 0, &val);
@@ -580,27 +595,33 @@ static int filter_add_pred(struct filter_parse_state *ps, 
			return -EINVAL;

		}

		pred->val = val;

	}



	fn = select_comparison_fn(pred->op, field->size, field->is_signed);

		fn = select_comparison_fn(pred->op, field->size,

					  field->is_signed);

		if (!fn) {

			parse_error(ps, FILT_ERR_INVALID_OP, 0);

			return -EINVAL;

		}

	}



	if (pred->op == OP_NE)

		pred->not = 1;



add_pred_fn:

	if (!dry_run)

		return filter_add_pred_fn(ps, call, pred, fn);

	return 0;

}



static int filter_add_subsystem_pred(struct filter_parse_state *ps,

				     struct event_subsystem *system,

				     struct filter_pred *pred,

				     char *filter_string)

				     char *filter_string,

				     bool dry_run)

{

	struct ftrace_event_call *call;

	int err = 0;

	bool fail = true;



	list_for_each_entry(call, &ftrace_events, list) {
@@ -610,17 +631,25 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps, 
		if (strcmp(call->system, system->name))

			continue;



		err = filter_add_pred(ps, call, pred);

		if (err) {

			filter_free_subsystem_preds(system);

			parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);

			goto out;

		}

		if (call->filter->no_reset)

			continue;



		err = filter_add_pred(ps, call, pred, dry_run);

		if (err)

			call->filter->no_reset = true;

		else

			fail = false;



		if (!dry_run)

			replace_filter_string(call->filter, filter_string);

	}

out:



	if (fail) {

		parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);

		return err;

	}

	return 0;

}



static void parse_init(struct filter_parse_state *ps,

		       struct filter_op *ops,
@@ -978,12 +1007,14 @@ static int check_preds(struct filter_parse_state *ps) 
static int replace_preds(struct event_subsystem *system,

			 struct ftrace_event_call *call,

			 struct filter_parse_state *ps,

			 char *filter_string)

			 char *filter_string,

			 bool dry_run)

{

	char *operand1 = NULL, *operand2 = NULL;

	struct filter_pred *pred;

	struct postfix_elt *elt;

	int err;

	int n_preds = 0;



	err = check_preds(ps);

	if (err)
@@ -1002,19 +1033,14 @@ static int replace_preds(struct event_subsystem *system, 
			continue;

		}



		if (n_preds++ == MAX_FILTER_PRED) {

			parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);

			return -ENOSPC;

		}



		if (elt->op == OP_AND || elt->op == OP_OR) {

			pred = create_logical_pred(elt->op);

			if (call)

				err = filter_add_pred(ps, call, pred);

			else

				err = filter_add_subsystem_pred(ps, system,

							pred, filter_string);

			filter_free_pred(pred);

			if (err)

				return err;



			operand1 = operand2 = NULL;

			continue;

			goto add_pred;

		}



		if (!operand1 || !operand2) {
@@ -1023,11 +1049,12 @@ static int replace_preds(struct event_subsystem *system, 
		}



		pred = create_pred(elt->op, operand1, operand2);

add_pred:

		if (call)

			err = filter_add_pred(ps, call, pred);

			err = filter_add_pred(ps, call, pred, false);

		else

			err = filter_add_subsystem_pred(ps, system, pred,

							filter_string);

						filter_string, dry_run);

		filter_free_pred(pred);

		if (err)

			return err;
@@ -1068,7 +1095,7 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string) 
		goto out;

	}



	err = replace_preds(NULL, call, ps, filter_string);

	err = replace_preds(NULL, call, ps, filter_string, false);

	if (err)

		append_filter_err(ps, call->filter);
@@ -1092,7 +1119,7 @@ int apply_subsystem_event_filter(struct event_subsystem *system, 
	mutex_lock(&event_mutex);



	if (!strcmp(strstrip(filter_string), "0")) {

		filter_free_subsystem_preds(system);

		filter_free_subsystem_preds(system, FILTER_DISABLE_ALL);

		remove_filter_string(system->filter);

		mutex_unlock(&event_mutex);

		return 0;
@@ -1103,7 +1130,6 @@ int apply_subsystem_event_filter(struct event_subsystem *system, 
	if (!ps)

		goto out_unlock;



	filter_free_subsystem_preds(system);

	replace_filter_string(system->filter, filter_string);



	parse_init(ps, filter_ops, filter_string);
@@ -1113,9 +1139,23 @@ int apply_subsystem_event_filter(struct event_subsystem *system, 
		goto out;

	}



	err = replace_preds(system, NULL, ps, filter_string);

	if (err)

	filter_free_subsystem_preds(system, FILTER_INIT_NO_RESET);



	/* try to see the filter can be applied to which events */

	err = replace_preds(system, NULL, ps, filter_string, true);

	if (err) {

		append_filter_err(ps, system->filter);

		goto out;

	}



	filter_free_subsystem_preds(system, FILTER_SKIP_NO_RESET);



	/* really apply the filter to the events */

	err = replace_preds(system, NULL, ps, filter_string, false);

	if (err) {

		append_filter_err(ps, system->filter);

		filter_free_subsystem_preds(system, 2);

	}



out:

	filter_opstack_clear(ps);

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