rv: Fix wrong type cast in reactors_show() and monitor_reactor_show()

Argument 'p' of reactors_show() and monitor_reactor_show() is not a pointer
to struct rv_reactor, it is actually a pointer to the list_head inside
struct rv_reactor. Therefore it's wrong to cast 'p' to struct rv_reactor *.

This wrong type cast has been there since the beginning. But it still
worked because the list_head was the first field in struct rv_reactor_def.
This is no longer true since commit 3d3c376 ("rv: Merge struct
rv_reactor_def into struct rv_reactor") moved the list_head, and this wrong
type cast became a functional problem.

Properly use container_of() instead.

Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Gabriele Monaco <[email protected]>
Link: https://lore.kernel.org/b4febbd6844311209e4c8768b65d508b81bd8c9b.1753625621.git.namcao@linutronix.de
Fixes: 3d3c376 ("rv: Merge struct rv_reactor_def into struct rv_reactor")
Signed-off-by: Nam Cao <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: covanam

kernel/trace/rv/rv_reactors.c

@@ -86,7 +86,7 @@ static struct rv_reactor *get_reactor_rdef_by_name(char *name)
  */
 static int reactors_show(struct seq_file *m, void *p)
 {
-	struct rv_reactor *reactor = p;
+	struct rv_reactor *reactor = container_of(p, struct rv_reactor, list);
 
 	seq_printf(m, "%s\n", reactor->name);
 	return 0;
@@ -139,7 +139,7 @@ static const struct file_operations available_reactors_ops = {
 static int monitor_reactor_show(struct seq_file *m, void *p)
 {
 	struct rv_monitor *mon = m->private;
-	struct rv_reactor *reactor = p;
+	struct rv_reactor *reactor = container_of(p, struct rv_reactor, list);
 
 	if (mon->reactor == reactor)
 		seq_printf(m, "[%s]\n", reactor->name);