tracing/osnoise: Use built-in RCU list checking

[ Upstream commit 685b64e4d6da4be8b4595654a57db663b3d1dfc2 ]

list_for_each_entry_rcu() has built-in RCU and lock checking.

Pass cond argument to list_for_each_entry_rcu() to silence false lockdep
warning when CONFIG_PROVE_RCU_LIST is enabled.

Execute as follow:

 [tracing]# echo osnoise > current_tracer
 [tracing]# echo 1 > tracing_on
 [tracing]# echo 0 > tracing_on

The trace_types_lock is held when osnoise_tracer_stop() or
timerlat_tracer_stop() are called in the non-RCU read side section.
So, pass lockdep_is_held(&trace_types_lock) to silence false lockdep
warning.

Link: https://lkml.kernel.org/r/20221227023036.784337-1-nashuiliang@gmail.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: dae181349f1e ("tracing/osnoise: Support a list of trace_array *tr")
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Chuang Wang <nashuiliang@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 4300c5d..1c07efc 100644 (file)
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -125,9 +125,8 @@ static void osnoise_unregister_instance(struct trace_array *tr)
         * register/unregister serialization is provided by trace's
         * trace_types_lock.
         */
-       lockdep_assert_held(&trace_types_lock);
-
-       list_for_each_entry_rcu(inst, &osnoise_instances, list) {
+       list_for_each_entry_rcu(inst, &osnoise_instances, list,
+                               lockdep_is_held(&trace_types_lock)) {
                if (inst->tr == tr) {
                        list_del_rcu(&inst->list);
                        found = 1;