Return-path: Received: from mx1.redhat.com ([209.132.183.28]:42746 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964791AbdKGKNY (ORCPT ); Tue, 7 Nov 2017 05:13:24 -0500 Date: Tue, 7 Nov 2017 11:13:22 +0100 From: Stanislaw Gruszka To: Richard Genoud Cc: Helmut Schaa , "linux-kernel@vger.kernel.org" , linux-wireless@vger.kernel.org Subject: Re: Soft lockup in rt2x00usb_work_rxdone() Message-ID: <20171107101320.GA12140@redhat.com> (sfid-20171107_111602_667784_D3027694) References: <1509983829.10974.2.camel@gmail.com> <20171107085327.GA11380@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, Nov 07, 2017 at 11:06:39AM +0100, Richard Genoud wrote: > > 3 short articles how to configure and use ftrace are here: > > https://lwn.net/Articles/365835/ > > https://lwn.net/Articles/366796/ > > https://lwn.net/Articles/370423/ > > > I tried with ftrace, but I don't think there's a way to dump the trace > when there's a soft lock-up > (I can't do anything after the unbind, even the heartbeat led stopped blinking). > I saw the /proc/sys/kernel/ftrace_dump_on_oops file, but there's no > /proc/sys/kernel/ftrace_dump_on_soft_lock-up file :) You should configure function trace with rt2x* functions. After that start tracing, unbind the device, then stop tracing and provide trace output. Thanks Stanislaw