From: "Steven Rostedt (VMware)" <[email protected]> Stack tracing discovered that there's a small location inside the RCU infrastructure where calling rcu_irq_enter() does not work. As trace events use rcu_irq_enter() it must make sure that it is functionable. A check against rcu_irq_enter_disabled() is added with a WARN_ON_ONCE() as no trace event should ever be used in that part of RCU. If the warning is triggered, then the trace event is ignored.
Link: http://lkml.kernel.org/r/[email protected] Cc: Mathieu Desnoyers <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- Mathieu, is this better? (yeah, i left in functionable, because I like that word ;-) include/linux/tracepoint.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index f72fcfe..352f32a 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -151,7 +151,12 @@ extern void syscall_unregfunc(void); } while (0) #ifndef MODULE -#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ +#define TRACE_RCU_IRQ_ENTER_CHECK \ + if (WARN_ON_ONCE(rcu_irq_enter_disabled())) \ + return; \ + rcu_irq_enter_irqson() + +#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ static inline void trace_##name##_rcuidle(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ @@ -159,7 +164,7 @@ extern void syscall_unregfunc(void); TP_PROTO(data_proto), \ TP_ARGS(data_args), \ TP_CONDITION(cond), \ - rcu_irq_enter_irqson(), \ + PARAMS(TRACE_RCU_IRQ_ENTER_CHECK), \ rcu_irq_exit_irqson()); \ } #else -- 2.9.3
