On Tue, Jul 17, 2018 at 08:25:28PM +0200, Peter Zijlstra wrote: > On Fri, Jul 13, 2018 at 02:55:46PM -0700, Joel Fernandes wrote: > > + /* keep srcu and sched-rcu usage consistent */ \ > > + preempt_disable_notrace(); \ > > + \ > > + /* \ > > + * For rcuidle callers, use srcu since sched-rcu \ > > + * doesn't work from the idle path. \ > > + */ \ > > + if (rcuidle) \ > > + idx = srcu_read_lock_notrace(&tracepoint_srcu); \ > > + else \ > > + rcu_read_lock_sched_notrace(); \ > > That else is completely superfluous. rcu_read_lock_sched_notrace() := > prempt_disable_notrace().
I have a patch as below on top of this series. Thanks for the suggestion. Steve, Peter, Is it Ok with you to take the below patch ontop of this series? I avoided resending the 3-patch series since this is the only change, but let me know what you prefer or makes it easy for you. ------->8-------- From: Joel Fernandes <[email protected]> Subject: [PATCH] tracepoint: Remove extra unneeded rcu_read_lock_sched_notrace A great idea was provided that rcu_read_lock_sched_notrace being the equivalent of preempt_disable_notrace is unnecessary to call in tracepoint code, since we already call preempt_disable_notrace in advance. So lets remove the extra call. Suggested-by: Peter Zijlstra <[email protected]> Signed-off-by: Joel Fernandes <[email protected]> --- include/linux/tracepoint.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 97e1d365a817..6e7bc6ebfcd8 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -161,8 +161,6 @@ extern void syscall_unregfunc(void); */ \ if (rcuidle) \ idx = srcu_read_lock_notrace(&tracepoint_srcu); \ - else \ - rcu_read_lock_sched_notrace(); \ \ it_func_ptr = rcu_dereference_raw((tp)->funcs); \ \ @@ -176,8 +174,6 @@ extern void syscall_unregfunc(void); \ if (rcuidle) \ srcu_read_unlock_notrace(&tracepoint_srcu, idx);\ - else \ - rcu_read_unlock_sched_notrace(); \ \ preempt_enable_notrace(); \ } while (0) -- 2.18.0.203.gfac676dfb9-goog
