From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: timer: lockup in run_timer_softirq() Date: Thu, 11 Jul 2013 12:59:32 -0400 Message-ID: <1373561972.17876.51.camel@gandalf.local.home> References: <51DC902F.3070403@oracle.com> <20130709224706.GA13855@redhat.com> <51DC9379.9050408@oracle.com> <20130709230316.GB13855@redhat.com> <51DC983F.2010409@oracle.com> <20130710095210.GD17211@twins.programming.kicks-ass.net> <1373459254.7458.49.camel@gandalf.local.home> <20130710124245.GT25631@dyad.programming.kicks-ass.net> <1373461091.7458.55.camel@gandalf.local.home> <20130711164204.GK25631@dyad.programming.kicks-ass.net> <1373561726.17876.48.camel@gandalf.local.home> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1373561726.17876.48.camel@gandalf.local.home> Sender: trinity-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Peter Zijlstra Cc: Sasha Levin , Dave Jones , Tejun Heo , tglx@linutronix.de, LKML , trinity@vger.kernel.org On Thu, 2013-07-11 at 12:55 -0400, Steven Rostedt wrote: > > > > Other than that, a function tracer environment that is safer to use might be > > useful for other people as well. > > Not sure how to make the environment safe, as the main purpose of the > function trace is to debug those hard to debug locations, like NMIs, > RCU, dynamic ticks, etc. To ensure a "safe" environment, it would > cripple the tracer. > > Hmm, what would you state as a safe environment? How can we detect if > the environment is safe to trace or not? Maybe I misunderstood you. You mean to have this environment be something for not just perf, and have the macro be: NONSAFE_TRACE(__local_bh_enable); ? Then, any ftrace user could set a flag in the registering of its ops to 'safe_only_functions'. And it will ignore all of these locations. There's really not many of them, so it may not be too hard to weed out. -- Steve