Commit 408b9611 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

tracing: WARN on rcuidle 



ARCH_WANTS_NO_INSTR (a superset of CONFIG_GENERIC_ENTRY) disallows any
and all tracing when RCU isn't enabled.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Tested-by: default avatarTony Lindgren <tony@atomide.com>
Tested-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.416110581@infradead.org
parent dc730560

include/linux/tracepoint.h

+13 −2
Original line number Diff line number Diff line
@@ -177,6 +177,17 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
#define __DO_TRACE_CALL(name, args)	__traceiter_##name(NULL, args)

#endif /* CONFIG_HAVE_STATIC_CALL */



/*

 * ARCH_WANTS_NO_INSTR archs are expected to have sanitized entry and idle

 * code that disallow any/all tracing/instrumentation when RCU isn't watching.

 */

#ifdef CONFIG_ARCH_WANTS_NO_INSTR

#define RCUIDLE_COND(rcuidle)	(rcuidle)

#else

/* srcu can't be used from NMI */

#define RCUIDLE_COND(rcuidle)	(rcuidle && in_nmi())

#endif



/*

 * it_func[0] is never NULL because there is at least one element in the array

 * when the array itself is non NULL.
@@ -188,8 +199,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) 
		if (!(cond))						\

			return;						\

									\

		/* srcu can't be used from NMI */			\

		WARN_ON_ONCE(rcuidle && in_nmi());			\

		if (WARN_ON_ONCE(RCUIDLE_COND(rcuidle)))		\

			return;						\

									\

		/* keep srcu and sched-rcu usage consistent */		\

		preempt_disable_notrace();				\

kernel/trace/trace.c

+3 −0
Original line number Diff line number Diff line
@@ -3128,6 +3128,9 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, 
		return;

	}



	if (WARN_ON_ONCE(IS_ENABLED(CONFIG_GENERIC_ENTRY)))

		return;



	/*

	 * When an NMI triggers, RCU is enabled via ct_nmi_enter(),

	 * but if the above rcu_is_watching() failed, then the NMI