Commit 779c5e37 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Steven Rostedt
Browse files

tracing: Kill trace_create_file_ops() and friends 

trace_create_file_ops() allocates the copy of id/filter/format/enable
file_operations to set "f_op->owner = mod" for fops_get().

However after the recent changes there is no reason to prevent rmmod
even if one of these files is opened. A file operation can do nothing
but fail after remove_event_file_dir() clears ->i_private for every
file removed by trace_module_remove_events().

Kill "struct ftrace_module_file_ops" and fix the compilation errors.

Link: http://lkml.kernel.org/r/20130731173132.GA31033@redhat.com



Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 3ddc77f6

kernel/trace/trace_events.c

+9 −144
Original line number Diff line number Diff line
@@ -1683,8 +1683,7 @@ __trace_early_add_new_event(struct ftrace_event_call *call, 
}



struct ftrace_module_file_ops;

static void __add_event_to_tracers(struct ftrace_event_call *call,

				   struct ftrace_module_file_ops *file_ops);

static void __add_event_to_tracers(struct ftrace_event_call *call);



/* Add an additional event_call dynamically */

int trace_add_event_call(struct ftrace_event_call *call)
@@ -1695,7 +1694,7 @@ int trace_add_event_call(struct ftrace_event_call *call) 


	ret = __register_event(call, NULL);

	if (ret >= 0)

		__add_event_to_tracers(call, NULL);

		__add_event_to_tracers(call);



	mutex_unlock(&event_mutex);

	mutex_unlock(&trace_types_lock);
@@ -1769,100 +1768,21 @@ int trace_remove_event_call(struct ftrace_event_call *call) 


#ifdef CONFIG_MODULES



static LIST_HEAD(ftrace_module_file_list);



/*

 * Modules must own their file_operations to keep up with

 * reference counting.

 */

struct ftrace_module_file_ops {

	struct list_head		list;

	struct module			*mod;

	struct file_operations		id;

	struct file_operations		enable;

	struct file_operations		format;

	struct file_operations		filter;

};



static struct ftrace_module_file_ops *

find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)

{

	/*

	 * As event_calls are added in groups by module,

	 * when we find one file_ops, we don't need to search for

	 * each call in that module, as the rest should be the

	 * same. Only search for a new one if the last one did

	 * not match.

	 */

	if (file_ops && mod == file_ops->mod)

		return file_ops;



	list_for_each_entry(file_ops, &ftrace_module_file_list, list) {

		if (file_ops->mod == mod)

			return file_ops;

	}

	return NULL;

}



static struct ftrace_module_file_ops *

trace_create_file_ops(struct module *mod)

{

	struct ftrace_module_file_ops *file_ops;



	/*

	 * This is a bit of a PITA. To allow for correct reference

	 * counting, modules must "own" their file_operations.

	 * To do this, we allocate the file operations that will be

	 * used in the event directory.

	 */



	file_ops = kmalloc(sizeof(*file_ops), GFP_KERNEL);

	if (!file_ops)

		return NULL;



	file_ops->mod = mod;



	file_ops->id = ftrace_event_id_fops;

	file_ops->id.owner = mod;



	file_ops->enable = ftrace_enable_fops;

	file_ops->enable.owner = mod;



	file_ops->filter = ftrace_event_filter_fops;

	file_ops->filter.owner = mod;



	file_ops->format = ftrace_event_format_fops;

	file_ops->format.owner = mod;



	list_add(&file_ops->list, &ftrace_module_file_list);



	return file_ops;

}



static void trace_module_add_events(struct module *mod)

{

	struct ftrace_module_file_ops *file_ops = NULL;

	struct ftrace_event_call **call, **start, **end;



	start = mod->trace_events;

	end = mod->trace_events + mod->num_trace_events;



	if (start == end)

		return;



	file_ops = trace_create_file_ops(mod);

	if (!file_ops)

		return;



	for_each_event(call, start, end) {

		__register_event(*call, mod);

		__add_event_to_tracers(*call, file_ops);

		__add_event_to_tracers(*call);

	}

}



static void trace_module_remove_events(struct module *mod)

{

	struct ftrace_module_file_ops *file_ops;

	struct ftrace_event_call *call, *p;

	bool clear_trace = false;
@@ -1874,16 +1794,6 @@ static void trace_module_remove_events(struct module *mod) 
			__trace_remove_event_call(call);

		}

	}



	/* Now free the file_operations */

	list_for_each_entry(file_ops, &ftrace_module_file_list, list) {

		if (file_ops->mod == mod)

			break;

	}

	if (&file_ops->list != &ftrace_module_file_list) {

		list_del(&file_ops->list);

		kfree(file_ops);

	}

	up_write(&trace_event_sem);



	/*
@@ -1919,62 +1829,22 @@ static int trace_module_notify(struct notifier_block *self, 
	return 0;

}



static int

__trace_add_new_mod_event(struct ftrace_event_call *call,

			  struct trace_array *tr,

			  struct ftrace_module_file_ops *file_ops)

{

	return __trace_add_new_event(call, tr,

				     &file_ops->id, &file_ops->enable,

				     &file_ops->filter, &file_ops->format);

}



#else

static inline struct ftrace_module_file_ops *

find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)

{

	return NULL;

}

static inline int trace_module_notify(struct notifier_block *self,

				      unsigned long val, void *data)

{

	return 0;

}

static inline int

__trace_add_new_mod_event(struct ftrace_event_call *call,

			  struct trace_array *tr,

			  struct ftrace_module_file_ops *file_ops)

{

	return -ENODEV;

}

#endif /* CONFIG_MODULES */



/* Create a new event directory structure for a trace directory. */

static void

__trace_add_event_dirs(struct trace_array *tr)

{

	struct ftrace_module_file_ops *file_ops = NULL;

	struct ftrace_event_call *call;

	int ret;



	list_for_each_entry(call, &ftrace_events, list) {

		if (call->mod) {

			/*

			 * Directories for events by modules need to

			 * keep module ref counts when opened (as we don't

			 * want the module to disappear when reading one

			 * of these files). The file_ops keep account of

			 * the module ref count.

			 */

			file_ops = find_ftrace_file_ops(file_ops, call->mod);

			if (!file_ops)

				continue; /* Warn? */

			ret = __trace_add_new_mod_event(call, tr, file_ops);

			if (ret < 0)

				pr_warning("Could not create directory for event %s\n",

					   call->name);

			continue;

		}

		ret = __trace_add_new_event(call, tr,

					    &ftrace_event_id_fops,

					    &ftrace_enable_fops,
@@ -2332,16 +2202,11 @@ __trace_remove_event_dirs(struct trace_array *tr) 
		remove_event_file_dir(file);

}



static void

__add_event_to_tracers(struct ftrace_event_call *call,

		       struct ftrace_module_file_ops *file_ops)

static void __add_event_to_tracers(struct ftrace_event_call *call)

{

	struct trace_array *tr;



	list_for_each_entry(tr, &ftrace_trace_arrays, list) {

		if (file_ops)

			__trace_add_new_mod_event(call, tr, file_ops);

		else

		__trace_add_new_event(call, tr,

				      &ftrace_event_id_fops,

				      &ftrace_enable_fops,

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