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SubjectRe: [PATCH 7/5] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events
On Fri, Apr 07, 2017 at 01:06:15PM -0400, Steven Rostedt 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
> 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.
>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> ---
> 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; \
> rcu_irq_enter_irqson(), \
> rcu_irq_exit_irqson()); \
> }
> --
> 2.9.3
>

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