On Mon, Apr 30, 2018 at 06:42:01PM -0700, Joel Fernandes wrote:
> In this series, we are making lockdep use an rcuidle tracepoint. For
> this reason we need a notrace variant of srcu_dereference since
> otherwise we get lockdep splats since lockdep hooks may not have run
> yet. This patch adds the needed variant.
>
> Cc: Steven Rostedt <[email protected]>
> Cc: Peter Zilstra <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Mathieu Desnoyers <[email protected]>
> Cc: Tom Zanussi <[email protected]>
> Cc: Namhyung Kim <[email protected]>
> Cc: Thomas Glexiner <[email protected]>
> Cc: Boqun Feng <[email protected]>
> Cc: Paul McKenney <[email protected]>
> Cc: Frederic Weisbecker <[email protected]>
> Cc: Randy Dunlap <[email protected]>
> Cc: Masami Hiramatsu <[email protected]>
> Cc: Fenguang Wu <[email protected]>
> Cc: Baohong Liu <[email protected]>
> Cc: Vedang Patel <[email protected]>
> Cc: [email protected]
> Signed-off-by: Joel Fernandes <[email protected]>
> ---
> include/linux/srcu.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/srcu.h b/include/linux/srcu.h
> index 2ec618979b20..a1c4947be877 100644
> --- a/include/linux/srcu.h
> +++ b/include/linux/srcu.h
> @@ -135,6 +135,11 @@ static inline int srcu_read_lock_held(const struct
> srcu_struct *sp)
> */
> #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
>
> +/**
> + * srcu_dereference_notrace - no tracing and no lockdep calls from here
> + */
> +#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1)
Given that this is a one-liner, why not just use srcu_dereference_check()
directly, with 1 as you do above to disable lockdep?
Thanx, Paul
> +
> /**
> * srcu_read_lock - register a new reader for an SRCU-protected structure.
> * @sp: srcu_struct in which to register the new reader.
> --
> 2.17.0.441.gb46fe60e1d-goog
>
