From mboxrd@z Thu Jan 1 00:00:00 1970 From: rostedt@goodmis.org (Steven Rostedt) Date: Wed, 11 Jul 2018 09:00:03 -0400 Subject: [PATCH v9 4/7] tracepoint: Make rcuidle tracepoint callers use SRCU In-Reply-To: <20180711124954.GE2476@hirez.programming.kicks-ass.net> References: <20180628182149.226164-1-joel@joelfernandes.org> <20180628182149.226164-5-joel@joelfernandes.org> <20180711124954.GE2476@hirez.programming.kicks-ass.net> Message-ID: <20180711090003.42596c2b@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" Message-ID: <20180711130003.V5cdxh6RSlUCg1-qizZrugpXdgzwdvENf582U_ozCxY@z> On Wed, 11 Jul 2018 14:49:54 +0200 Peter Zijlstra wrote: > On Thu, Jun 28, 2018@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. The problem with doing this is if we use a trace event without the proper _idle() or whatever, we wont get a warning that it is used incorrectly with lockdep. Or does lockdep still check if "rcu is watching" with rcu_dereference_raw()? -- Steve > > > + \ > > + /* \ > > + * 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); \ > > + } \ -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html