Re: [PATCH 8/8] tracing: Remove regular RCU context for _rcuidle tracepoints (again)

Steven Rostedt
2020-02-12T14:29:56Z

On Wed, 12 Feb 2020 10:32:18 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> Effectively revert commit 865e63b04e9b2 ("tracing: Add back in
> rcu_irq_enter/exit_irqson() for rcuidle tracepoints") now that we've
> taught perf how to deal with not having an RCU context provided.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> include/linux/tracepoint.h | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -179,10 +179,8 @@ static inline struct tracepoint *tracepo
> * For rcuidle callers, use srcu since sched-rcu \
> * doesn't work from the idle path. \
> */ \
> - if (rcuidle) { \
> + if (rcuidle) \
> __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
> - rcu_irq_enter_irqsave(); \
> - } \
> \
> it_func_ptr = rcu_dereference_raw((tp)->funcs); \
> \
> @@ -194,10 +192,8 @@ static inline struct tracepoint *tracepo
> } while ((++it_func_ptr)->func); \
> } \
> \
> - if (rcuidle) { \
> - rcu_irq_exit_irqsave(); \
> + if (rcuidle) \
> srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
> - } \
> \
> preempt_enable_notrace(); \
> } while (0)
>

Which looks basically the same as this patch...

https://lore.kernel.org/r/20200211095047.58ddf750@gandalf.local.home

-- Steve