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tracing: Simplify event_enable_func() goto out_free logic

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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: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2024-12-19 15:12:02 -05:00 committed by Steven Rostedt (Google)
parent cad1d5bd2c
commit c949dfb974
1 changed files with 14 additions and 14 deletions
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28
kernel/trace/trace_events.c
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@ -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;
}