Merge tag 'trace-v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Do not allow histogram values to have modifies. They can cause a NULL
   pointer dereference if they do.

 - Warn if hist_field_name() is passed a NULL. Prevent the NULL pointer
   dereference mentioned above.

 - Fix invalid address look up race in lookup_rec()

 - Define ftrace_stub_graph conditionally to prevent linker errors

 - Always check if RCU is watching at all tracepoint locations

* tag 'trace-v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Make tracepoint lockdep check actually test something
  ftrace,kcfi: Define ftrace_stub_graph conditionally
  ftrace: Fix invalid address access in lookup_rec() when index is 0
  tracing: Check field value in hist_field_name()
  tracing: Do not let histogram values have some modifiers

1 files changed, 6 insertions, 9 deletions

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index e299f29375bb..6811e43c1b5c 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -242,12 +242,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
  * not add unwanted padding between the beginning of the section and the
  * structure. Force alignment to the same alignment as the section start.
  *
- * When lockdep is enabled, we make sure to always do the RCU portions of
- * the tracepoint code, regardless of whether tracing is on. However,
- * don't check if the condition is false, due to interaction with idle
- * instrumentation. This lets us find RCU issues triggered with tracepoints
- * even when this tracepoint is off. This code has no purpose other than
- * poking RCU a bit.
+ * When lockdep is enabled, we make sure to always test if RCU is
+ * "watching" regardless if the tracepoint is enabled or not. Tracepoints
+ * require RCU to be active, and it should always warn at the tracepoint
+ * site if it is not watching, as it will need to be active when the
+ * tracepoint is enabled.
  */
 #define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\
 	extern int __traceiter_##name(data_proto);			\
@@ -260,9 +259,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 				TP_ARGS(args),				\
 				TP_CONDITION(cond), 0);			\
 		if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {		\
-			rcu_read_lock_sched_notrace();			\
-			rcu_dereference_sched(__tracepoint_##name.funcs);\
-			rcu_read_unlock_sched_notrace();		\
+			WARN_ON_ONCE(!rcu_is_watching());		\
 		}							\
 	}								\
 	__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),		\