tracing: Switch trace_events_hist.c code over to use guard()

There are a couple functions in trace_events_hist.c that have "goto out" or
equivalent on error in order to release locks that were taken. This can be
error prone or just simply make the code more complex.

Switch every location that ends with unlocking a mutex on error over to
using the guard(mutex)() infrastructure to let the compiler worry about
releasing locks. This makes the code easier to read and understand.

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/20241219201345.694601480@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 9c058aa8baf332a51d3fc771a4dff97e62d04162..879b58892b9d4538e48edaaf88d848e4c45fa4f6 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -5594,25 +5594,19 @@ static int hist_show(struct seq_file *m, void *v)
 {
        struct event_trigger_data *data;
        struct trace_event_file *event_file;
-       int n = 0, ret = 0;
+       int n = 0;
 
-       mutex_lock(&event_mutex);
+       guard(mutex)(&event_mutex);
 
        event_file = event_file_file(m->private);
-       if (unlikely(!event_file)) {
-               ret = -ENODEV;
-               goto out_unlock;
-       }
+       if (unlikely(!event_file))
+               return -ENODEV;
 
        list_for_each_entry(data, &event_file->triggers, list) {
                if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
                        hist_trigger_show(m, data, n++);
        }
-
- out_unlock:
-       mutex_unlock(&event_mutex);
-
-       return ret;
+       return 0;
 }
 
 static int event_hist_open(struct inode *inode, struct file *file)
@@ -5873,25 +5867,19 @@ static int hist_debug_show(struct seq_file *m, void *v)
 {
        struct event_trigger_data *data;
        struct trace_event_file *event_file;
-       int n = 0, ret = 0;
+       int n = 0;
 
-       mutex_lock(&event_mutex);
+       guard(mutex)(&event_mutex);
 
        event_file = event_file_file(m->private);
-       if (unlikely(!event_file)) {
-               ret = -ENODEV;
-               goto out_unlock;
-       }
+       if (unlikely(!event_file))
+               return -ENODEV;
 
        list_for_each_entry(data, &event_file->triggers, list) {
                if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
                        hist_trigger_debug_show(m, data, n++);
        }
-
- out_unlock:
-       mutex_unlock(&event_mutex);
-
-       return ret;
+       return 0;
 }
 
 static int event_hist_debug_open(struct inode *inode, struct file *file)