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Commit dc82ec98 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Ingo Molnar
Browse files

tracing/filter: Remove empty subsystem and its directory 



Remove empty subsystem and its directory when module unload.

Before patch:
 # rmmod trace-events-sample.ko
 # ls sample
 enable  filter

After patch:
 # rmmod trace-events-sample.ko
 # ls sample
 ls: cannot access sample: No such file or directory

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: default avatarTom Zanussi <tzanussi@gmail.com>
Reviewed-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A55A8BE.9010707@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c5cb1836

kernel/trace/trace.h

+1 −0
Original line number Diff line number Diff line
@@ -757,6 +757,7 @@ struct event_subsystem { 
	const char		*name;

	struct dentry		*entry;

	void			*filter;

	int			nr_events;

};



struct filter_pred;

kernel/trace/trace_events.c

+31 −1
Original line number Diff line number Diff line
@@ -851,9 +851,11 @@ event_subsystem_dir(const char *name, struct dentry *d_events) 


	/* First see if we did not already create this dir */

	list_for_each_entry(system, &event_subsystems, list) {

		if (strcmp(system->name, name) == 0)

		if (strcmp(system->name, name) == 0) {

			system->nr_events++;

			return system->entry;

		}

	}



	/* need to create new entry */

	system = kmalloc(sizeof(*system), GFP_KERNEL);
@@ -871,6 +873,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events) 
		return d_events;

	}



	system->nr_events = 1;

	system->name = kstrdup(name, GFP_KERNEL);

	if (!system->name) {

		debugfs_remove(system->entry);
@@ -905,6 +908,32 @@ event_subsystem_dir(const char *name, struct dentry *d_events) 
	return system->entry;

}



static void remove_subsystem_dir(const char *name)

{

	struct event_subsystem *system;



	if (strcmp(name, TRACE_SYSTEM) == 0)

		return;



	list_for_each_entry(system, &event_subsystems, list) {

		if (strcmp(system->name, name) == 0) {

			if (!--system->nr_events) {

				struct event_filter *filter = system->filter;



				debugfs_remove_recursive(system->entry);

				list_del(&system->list);

				if (filter) {

					kfree(filter->filter_string);

					kfree(filter);

				}

				kfree(system->name);

				kfree(system);

			}

			break;

		}

	}

}



static int

event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,

		 const struct file_operations *id,
@@ -1079,6 +1108,7 @@ static void trace_module_remove_events(struct module *mod) 
			list_del(&call->list);

			trace_destroy_fields(call);

			destroy_preds(call);

			remove_subsystem_dir(call->system);

		}

	}