----- On Apr 7, 2017, at 1:06 PM, rostedt [email protected] wrote: > From: "Steven Rostedt (VMware)" <[email protected]> > > Stack tracing discovered that there's a small location inside the RCU > infrastructure that calling rcu_irq_enter() does not work. As trace events
that -> where Do you have a link to the lkml thread where this stack tracing discovery happened ? > use rcu_irq_enter() it must make sure that it is functionable. A check I don't think functionable is the word you are looking for here. Perhaps "must make sure that it can be invoked" ? > 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. > > Cc: Mathieu Desnoyers <[email protected]> > Signed-off-by: Steven Rostedt (VMware) <[email protected]> > --- > include/linux/tracepoint.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index f72fcfe..8baef96 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -159,6 +159,8 @@ extern void syscall_unregfunc(void); > TP_PROTO(data_proto), \ > TP_ARGS(data_args), \ > TP_CONDITION(cond), \ > + if (WARN_ON_ONCE(rcu_irq_enter_disabled())) \ > + return; \ I must admit that it's a bit odd to have: if (WARN_ON_ONCE(rcu_irq_enter_disabled())) return; rcu_irq_enter_irqson() as one argument to the __DO_TRACE() macro. To me it's a bit unexpected coding-style wise. Am I the only one not comfortable with the proposed syntax ? Thanks, Mathieu > rcu_irq_enter_irqson(), \ > rcu_irq_exit_irqson()); \ > } > -- > 2.9.3 -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
