Commit 315326c1 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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tracing: Fix trace events build without modules 



The new multi-buffers added a descriptor that kept track of module
events, and the directories they use, with struct ftace_module_file_ops.
This is used to add a ref count to keep modules from unloading while
their files are being accessed.

As the descriptor is only needed when CONFIG_MODULES is enabled, it
is only declared when the config is enabled. But that struct is
dereferenced in a few areas outside the #ifdef CONFIG_MODULES.

By adding some helper routines and moving code around a little,
events can be compiled again without modules.

Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 34ef61b1

kernel/trace/trace_events.c

+36 −19
Original line number Diff line number Diff line
@@ -1546,9 +1546,18 @@ struct ftrace_module_file_ops { 
	struct file_operations		filter;

};



static struct ftrace_module_file_ops *find_ftrace_file_ops(struct module *mod)

static struct ftrace_module_file_ops *

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

{

	struct ftrace_module_file_ops *file_ops;

	/*

	 * 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)
@@ -1664,16 +1673,35 @@ 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 struct ftrace_module_file_ops *find_ftrace_file_ops(struct module *mod)

static inline struct ftrace_module_file_ops *

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

{

	return NULL;

}

static int trace_module_notify(struct notifier_block *self,

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. */
@@ -1692,20 +1720,11 @@ __trace_add_event_dirs(struct trace_array *tr) 
			 * want the module to disappear when reading one

			 * of these files). The file_ops keep account of

			 * the module ref count.

			 *

			 * 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 || call->mod != file_ops->mod)

				file_ops = find_ftrace_file_ops(call->mod);

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

			if (!file_ops)

				continue; /* Warn? */

			ret = __trace_add_new_event(call, tr,

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

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

			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);
@@ -1794,9 +1813,7 @@ __add_event_to_tracers(struct ftrace_event_call *call, 


	list_for_each_entry(tr, &ftrace_trace_arrays, list) {

		if (file_ops)

			__trace_add_new_event(call, tr,

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

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

			__trace_add_new_mod_event(call, tr, file_ops);

		else

			__trace_add_new_event(call, tr,

					      &ftrace_event_id_fops,

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