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tracing: Add rmdir to remove multibuffer instances

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Add a method to the hijacked dentry descriptor of the
"instances" directory to allow for rmdir to remove an
instance of a multibuffer.

Example:

  cd /debug/tracing/instances
  mkdir hello
  ls
hello/
  rmdir hello
  ls

Like the mkdir method, the i_mutex is dropped for the instances
directory. The instances directory is created at boot up and can
not be renamed or removed. The trace_types_lock mutex is used to
synchronize adding and removing of instances.

I've run several stress tests with different threads trying to
create and delete directories of the same name, and it has stood
up fine.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2012-08-07 16:14:16 -04:00
committed by Steven Rostedt
parent 277ba04461
commit 0c8916c342
3 changed files with 102 additions and 0 deletions
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33
kernel/trace/trace_events.c
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@ -1709,6 +1709,20 @@ __trace_add_event_dirs(struct trace_array *tr)
}
}
/* Remove the event directory structure for a trace directory. */
static void
__trace_remove_event_dirs(struct trace_array *tr)
{
struct ftrace_event_file *file, *next;
list_for_each_entry_safe(file, next, &tr->events, list) {
list_del(&file->list);
debugfs_remove_recursive(file->dir);
remove_subsystem(file->system);
kfree(file);
}
}
static void
__add_event_to_tracers(struct ftrace_event_call *call,
struct ftrace_module_file_ops *file_ops)
@ -1793,6 +1807,25 @@ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
return 0;
}
int event_trace_del_tracer(struct trace_array *tr)
{
/* Disable any running events */
__ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
mutex_lock(&event_mutex);
down_write(&trace_event_mutex);
__trace_remove_event_dirs(tr);
debugfs_remove_recursive(tr->event_dir);
up_write(&trace_event_mutex);
tr->event_dir = NULL;
mutex_unlock(&event_mutex);
return 0;
}
static __init int event_trace_enable(void)
{
struct trace_array *tr = top_trace_array();