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: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Reviewed-by: Li 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: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 52eb0d8..94305c7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -757,6 +757,7 @@
const char *name;
struct dentry *entry;
void *filter;
+ int nr_events;
};
struct filter_pred;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index fecac13..90cf936 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -851,8 +851,10 @@
/* 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 */
@@ -871,6 +873,7 @@
return d_events;
}
+ system->nr_events = 1;
system->name = kstrdup(name, GFP_KERNEL);
if (!system->name) {
debugfs_remove(system->entry);
@@ -905,6 +908,32 @@
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 @@
list_del(&call->list);
trace_destroy_fields(call);
destroy_preds(call);
+ remove_subsystem_dir(call->system);
}
}