Commit d099dbfd authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

cpuidle: tracing: Warn about !rcu_is_watching() 



When using noinstr, WARN when tracing hits when RCU is disabled.

Suggested-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126151323.466670589@infradead.org
parent 5a5d7e9b

include/linux/trace_recursion.h

+18 −0
Original line number Diff line number Diff line
@@ -135,6 +135,21 @@ extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip); 
# define do_ftrace_record_recursion(ip, pip)	do { } while (0)

#endif



#ifdef CONFIG_ARCH_WANTS_NO_INSTR

# define trace_warn_on_no_rcu(ip)					\

	({								\

		bool __ret = !rcu_is_watching();			\

		if (__ret && !trace_recursion_test(TRACE_RECORD_RECURSION_BIT)) { \

			trace_recursion_set(TRACE_RECORD_RECURSION_BIT); \

			WARN_ONCE(true, "RCU not on for: %pS\n", (void *)ip); \

			trace_recursion_clear(TRACE_RECORD_RECURSION_BIT); \

		}							\

		__ret;							\

	})

#else

# define trace_warn_on_no_rcu(ip)	false

#endif



/*

 * Preemption is promised to be disabled when return bit >= 0.

 */
@@ -144,6 +159,9 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign 
	unsigned int val = READ_ONCE(current->trace_recursion);

	int bit;



	if (trace_warn_on_no_rcu(ip))

		return -1;



	bit = trace_get_context_bit() + start;

	if (unlikely(val & (1 << bit))) {

		/*