Commit b8cc44a4 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (Google)
Browse files

tracing: Remove logic for registering multiple event triggers at a time 

Code for registering triggers assumes it's possible to register more
than one trigger at a time.  In fact, it's unimplemented and there
doesn't seem to be a reason to do that.

Remove the n_registered param from event_trigger_register() and fix up
callers.

Doing so simplifies the logic in event_trigger_register to the point
that it just becomes a wrapper calling event_command.reg().

It also removes the problematic call to event_command.unreg() in case
of failure.  A new function, event_trigger_unregister() is also added
for callers to call themselves.

The changes to trace_events_hist.c simply allow compilation; a
separate patch follows which updates the hist triggers to work
correctly with the new changes.

Link: https://lkml.kernel.org/r/6149fec7a139d93e84fa4535672fb5bef88006b0.1644010575.git.zanussi@kernel.org



Signed-off-by: default avatarTom Zanussi <zanussi@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 217d8c05

kernel/trace/trace.h

+5 −4
Original line number Diff line number Diff line
@@ -1629,10 +1629,11 @@ extern void event_trigger_reset_filter(struct event_command *cmd_ops, 
extern int event_trigger_register(struct event_command *cmd_ops,

				  struct trace_event_file *file,

				  char *glob,

				  char *cmd,

				  char *trigger,

				  struct event_trigger_data *trigger_data,

				  int *n_registered);

				  struct event_trigger_data *trigger_data);

extern void event_trigger_unregister(struct event_command *cmd_ops,

				     struct trace_event_file *file,

				     char *glob,

				     struct event_trigger_data *trigger_data);



/**

 * struct event_trigger_ops - callbacks for trace event triggers

kernel/trace/trace_events_hist.c

+6 −11
Original line number Diff line number Diff line
@@ -6287,7 +6287,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, 
			goto out_free;

		}



		cmd_ops->unreg(glob+1, trigger_data, file);

		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);

		se_name = trace_event_name(file->event_call);

		se = find_synth_event(se_name);

		if (se)
@@ -6296,13 +6296,10 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, 
		goto out_free;

	}



	ret = cmd_ops->reg(glob, trigger_data, file);

	/*

	 * The above returns on success the # of triggers registered,

	 * but if it didn't register any it returns zero.  Consider no

	 * triggers registered a failure too.

	 */

	if (!ret) {

	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);

	if (ret)

		goto out_free;

	if (ret == 0) {

		if (!(attrs->pause || attrs->cont || attrs->clear))

			ret = -ENOENT;

		goto out_free;
@@ -6331,15 +6328,13 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, 
	se = find_synth_event(se_name);

	if (se)

		se->ref++;

	/* Just return zero, not the number of registered triggers */

	ret = 0;

 out:

	if (ret == 0)

		hist_err_clear();



	return ret;

 out_unreg:

	cmd_ops->unreg(glob+1, trigger_data, file);

	event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);

 out_free:

	if (cmd_ops->set_filter)

		cmd_ops->set_filter(NULL, trigger_data, NULL);

kernel/trace/trace_events_trigger.c

+34 −62
Original line number Diff line number Diff line
@@ -587,13 +587,12 @@ static int register_trigger(char *glob, 
	}



	list_add_rcu(&data->list, &file->triggers);

	ret++;



	update_cond_flag(file);

	if (trace_event_trigger_enable_disable(file, 1) < 0) {

	ret = trace_event_trigger_enable_disable(file, 1);

	if (ret < 0) {

		list_del_rcu(&data->list);

		update_cond_flag(file);

		ret--;

	}

out:

	return ret;
@@ -927,48 +926,37 @@ void event_trigger_reset_filter(struct event_command *cmd_ops, 
 * @cmd_ops: The event_command operations for the trigger

 * @file: The event file for the trigger's event

 * @glob: The trigger command string, with optional remove(!) operator

 * @cmd: The cmd string

 * @param: The param string

 * @trigger_data: The trigger_data for the trigger

 * @n_registered: optional outparam, the number of triggers registered

 *

 * Register an event trigger.  The @cmd_ops are used to call the

 * cmd_ops->reg() function which actually does the registration. The

 * cmd_ops->reg() function returns the number of triggers registered,

 * which is assigned to n_registered, if n_registered is non-NULL.

 * cmd_ops->reg() function which actually does the registration.

 *

 * Return: 0 on success, errno otherwise

 */

int event_trigger_register(struct event_command *cmd_ops,

			   struct trace_event_file *file,

			   char *glob,

			   char *cmd,

			   char *param,

			   struct event_trigger_data *trigger_data,

			   int *n_registered)

			   struct event_trigger_data *trigger_data)

{

	int ret;



	if (n_registered)

		*n_registered = 0;

	return cmd_ops->reg(glob, trigger_data, file);

}



	ret = cmd_ops->reg(glob, trigger_data, file);

	/*

	 * The above returns on success the # of functions enabled,

	 * but if it didn't find any functions it returns zero.

	 * Consider no functions a failure too.

/**

 * event_trigger_unregister - unregister an event trigger

 * @cmd_ops: The event_command operations for the trigger

 * @file: The event file for the trigger's event

 * @glob: The trigger command string, with optional remove(!) operator

 * @trigger_data: The trigger_data for the trigger

 *

 * Unregister an event trigger.  The @cmd_ops are used to call the

 * cmd_ops->unreg() function which actually does the unregistration.

 */

	if (!ret) {

void event_trigger_unregister(struct event_command *cmd_ops,

			      struct trace_event_file *file,

			      char *glob,

			      struct event_trigger_data *trigger_data)

{

	cmd_ops->unreg(glob, trigger_data, file);

		ret = -ENOENT;

	} else if (ret > 0) {

		if (n_registered)

			*n_registered = ret;

		/* Just return zero, not the number of enabled functions */

		ret = 0;

	}



	return ret;

}



/*
@@ -1027,7 +1015,7 @@ event_trigger_parse(struct event_command *cmd_ops, 
	INIT_LIST_HEAD(&trigger_data->named_list);



	if (glob[0] == '!') {

		cmd_ops->unreg(glob+1, trigger_data, file);

		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);

		kfree(trigger_data);

		ret = 0;

		goto out;
@@ -1062,17 +1050,10 @@ event_trigger_parse(struct event_command *cmd_ops, 
 out_reg:

	/* Up the trigger_data count to make sure reg doesn't free it on failure */

	event_trigger_init(trigger_ops, trigger_data);

	ret = cmd_ops->reg(glob, trigger_data, file);

	/*

	 * The above returns on success the # of functions enabled,

	 * but if it didn't find any functions it returns zero.

	 * Consider no functions a failure too.

	 */

	if (!ret) {

		cmd_ops->unreg(glob, trigger_data, file);

		ret = -ENOENT;

	} else if (ret > 0)

		ret = 0;



	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);

	if (ret)

		goto out_free;



	/* Down the counter of trigger_data or free it if not used anymore */

	event_trigger_free(trigger_ops, trigger_data);
@@ -1854,7 +1835,7 @@ int event_enable_trigger_parse(struct event_command *cmd_ops, 
	trigger_data->private_data = enable_data;



	if (glob[0] == '!') {

		cmd_ops->unreg(glob+1, trigger_data, file);

		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);

		kfree(trigger_data);

		kfree(enable_data);

		ret = 0;
@@ -1901,19 +1882,11 @@ int event_enable_trigger_parse(struct event_command *cmd_ops, 
	ret = trace_event_enable_disable(event_enable_file, 1, 1);

	if (ret < 0)

		goto out_put;

	ret = cmd_ops->reg(glob, trigger_data, file);

	/*

	 * The above returns on success the # of functions enabled,

	 * but if it didn't find any functions it returns zero.

	 * Consider no functions a failure too.

	 */

	if (!ret) {

		ret = -ENOENT;

		goto out_disable;

	} else if (ret < 0)



	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);

	if (ret)

		goto out_disable;

	/* Just return zero, not the number of enabled functions */

	ret = 0;



	event_trigger_free(trigger_ops, trigger_data);

 out:

	return ret;
@@ -1959,13 +1932,12 @@ int event_enable_register_trigger(char *glob, 
	}



	list_add_rcu(&data->list, &file->triggers);

	ret++;



	update_cond_flag(file);

	if (trace_event_trigger_enable_disable(file, 1) < 0) {

	ret = trace_event_trigger_enable_disable(file, 1);

	if (ret < 0) {

		list_del_rcu(&data->list);

		update_cond_flag(file);

		ret--;

	}

out:

	return ret;