Commit c949dfb9 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
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tracing: Simplify event_enable_func() goto out_free logic 

The event_enable_func() function allocates the data descriptor early in
the function just to assign its data->count value via:

  kstrtoul(number, 0, &data->count);

This makes the code more complex as there are several error paths before
the data descriptor is actually used. This means there needs to be a
goto out_free; to clean it up.

Use a local variable "count" to do the update and move the data allocation
just before it is used. This removes the "out_free" label as the data can
be freed on the failure path of where it is used.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/20241219201345.190820140@goodmis.org


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent cad1d5bd

kernel/trace/trace_events.c

+14 −14
Original line number Diff line number Diff line
@@ -3758,6 +3758,7 @@ event_enable_func(struct trace_array *tr, struct ftrace_hash *hash, 
	struct trace_event_file *file;

	struct ftrace_probe_ops *ops;

	struct event_probe_data *data;

	unsigned long count = -1;

	const char *system;

	const char *event;

	char *number;
@@ -3798,14 +3799,6 @@ event_enable_func(struct trace_array *tr, struct ftrace_hash *hash, 


	ret = -ENOMEM;



	data = kzalloc(sizeof(*data), GFP_KERNEL);

	if (!data)

		goto out;



	data->enable = enable;

	data->count = -1;

	data->file = file;



	if (!param)

		goto out_reg;
@@ -3813,28 +3806,36 @@ event_enable_func(struct trace_array *tr, struct ftrace_hash *hash, 


	ret = -EINVAL;

	if (!strlen(number))

		goto out_free;

		goto out;



	/*

	 * We use the callback data field (which is a pointer)

	 * as our counter.

	 */

	ret = kstrtoul(number, 0, &data->count);

	ret = kstrtoul(number, 0, &count);

	if (ret)

		goto out_free;

		goto out;



 out_reg:

	/* Don't let event modules unload while probe registered */

	ret = trace_event_try_get_ref(file->event_call);

	if (!ret) {

		ret = -EBUSY;

		goto out_free;

		goto out;

	}



	ret = __ftrace_event_enable_disable(file, 1, 1);

	if (ret < 0)

		goto out_put;



	data = kzalloc(sizeof(*data), GFP_KERNEL);

	if (!data)

		goto out_put;



	data->enable = enable;

	data->count = count;

	data->file = file;



	ret = register_ftrace_function_probe(glob, tr, ops, data);

	/*

	 * The above returns on success the # of functions enabled,
@@ -3853,11 +3854,10 @@ event_enable_func(struct trace_array *tr, struct ftrace_hash *hash, 
	return ret;



 out_disable:

	kfree(data);

	__ftrace_event_enable_disable(file, 0, 1);

 out_put:

	trace_event_put_ref(file->event_call);

 out_free:

	kfree(data);

	goto out;

}