Messages in this thread | | | Date | Tue, 1 May 2018 07:18:17 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH RFC v5 3/6] srcu: Add notrace variant of srcu_dereference |
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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 <rostedt@goodmis.org> > Cc: Peter Zilstra <peterz@infradead.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > Cc: Tom Zanussi <tom.zanussi@linux.intel.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Thomas Glexiner <tglx@linutronix.de> > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Randy Dunlap <rdunlap@infradead.org> > Cc: Masami Hiramatsu <mhiramat@kernel.org> > Cc: Fenguang Wu <fengguang.wu@intel.com> > Cc: Baohong Liu <baohong.liu@intel.com> > Cc: Vedang Patel <vedang.patel@intel.com> > Cc: kernel-team@android.com > Signed-off-by: Joel Fernandes <joelaf@google.com> > --- > 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 >
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