From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756991AbdIHUAo (ORCPT ); Fri, 8 Sep 2017 16:00:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:49916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756764AbdIHUAn (ORCPT ); Fri, 8 Sep 2017 16:00:43 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8CEFA21D29 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Fri, 8 Sep 2017 16:00:39 -0400 From: Steven Rostedt To: Tom Zanussi Cc: tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org, vedang.patel@intel.com, bigeasy@linutronix.de, joel.opensrc@gmail.com, joelaf@google.com, mathieu.desnoyers@efficios.com, baohong.liu@intel.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Subject: Re: [PATCH v2 35/40] tracing: Reverse the order event_mutex/trace_types_lock are taken Message-ID: <20170908160039.24ab418c@gandalf.local.home> In-Reply-To: <20170908154136.096d49ff@gandalf.local.home> References: <4b52f9b1c49599780af1a193736df609b2785a63.1504642143.git.tom.zanussi@linux.intel.com> <20170908153135.14725f01@gandalf.local.home> <20170908154136.096d49ff@gandalf.local.home> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 8 Sep 2017 15:41:36 -0400 Steven Rostedt wrote: > On Fri, 8 Sep 2017 15:31:35 -0400 > Steven Rostedt wrote: > > > On Tue, 5 Sep 2017 16:57:47 -0500 > > Tom Zanussi wrote: > > > > > Change the order event_mutex and trace_types_lock are taken, to avoid > > > circular dependencies and lockdep spew. > > > > > > Changing the order shouldn't matter to any current code, but does to > > > anything that takes the event_mutex first and then trace_types_lock. > > > This is the case when calling tracing_set_clock from inside an event > > > command, which already holds the event_mutex. > > > > This is a very scary patch. I'll apply it and run a bunch of tests with > > lockdep enabled. Let's see what blows up (or not). > > Boom! > > It appears to be caused by instance creation. I'll look at that. OK, this may be a simple fix. I'll send you a patch to fold in after I finish testing it. -- Steve