Messages in this thread Patch in this message | | | Date | Fri, 7 Apr 2017 17:19:05 +0000 (UTC) | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 7/5] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events |
| |
----- On Apr 7, 2017, at 1:06 PM, rostedt rostedt@goodmis.org wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> > > 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 <mathieu.desnoyers@efficios.com> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > --- > 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
| |