Re: [PATCH v9 4/7] tracepoint: Make rcuidle tracepoint callers use SRCU

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Jun 28, 2018 at 11:21:46AM -0700, Joel Fernandes wrote:
> -		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\

I would convert to rcu_dereference_raw() to appease sparse. The fancy
stuff below is pointless if you then turn off all checking.

> +									\
> +		/*							\
> +		 * For rcuidle callers, use srcu since sched-rcu	\
> +		 * doesn't work from the idle path.			\
> +		 */							\
> +		if (rcuidle) {						\
> +			if (in_nmi()) {					\
> +				WARN_ON_ONCE(1);			\
> +				return; /* no srcu from nmi */		\
> +			}						\
> +									\
> +			idx = srcu_read_lock_notrace(&tracepoint_srcu);	\
> +			it_func_ptr =					\
> +				srcu_dereference_notrace((tp)->funcs,	\
> +						&tracepoint_srcu);	\
> +			/* To keep it consistent with !rcuidle path */	\
> +			preempt_disable_notrace();			\
> +		} else {						\
> +			rcu_read_lock_sched_notrace();			\
> +			it_func_ptr =					\
> +				rcu_dereference_sched((tp)->funcs);	\
> +		}							\