From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942694AbdEYQrH (ORCPT ); Thu, 25 May 2017 12:47:07 -0400 Received: from mail-it0-f49.google.com ([209.85.214.49]:35317 "EHLO mail-it0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942651AbdEYQrE (ORCPT ); Thu, 25 May 2017 12:47:04 -0400 Date: Thu, 25 May 2017 10:47:00 -0600 From: Mathieu Poirier To: Thomas Gleixner Cc: LKML , Peter Zijlstra , Ingo Molnar , Steven Rostedt , Sebastian Siewior , Paul McKenney , linux-arm-kernel@lists.infradead.org Subject: Re: [patch V3 12/32] hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked() Message-ID: <20170525164700.GB31052@xps15> References: <20170524081511.203800767@linutronix.de> <20170524081547.983493849@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170524081547.983493849@linutronix.de> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 24, 2017 at 10:15:23AM +0200, Thomas Gleixner wrote: > From: Sebastian Andrzej Siewior > > etm_probe4() holds get_online_cpus() while invoking > cpuhp_setup_state_nocalls(). > > cpuhp_setup_state_nocalls() invokes get_online_cpus() as well. This is > correct, but prevents the conversion of the hotplug locking to a percpu > rwsem. > > Use cpuhp_setup_state_nocalls_cpuslocked() to avoid the nested > call. Convert *_online_cpus() to the new interfaces while at it. > > Signed-off-by: Sebastian Andrzej Siewior > Signed-off-by: Thomas Gleixner > Cc: Mathieu Poirier > Cc: Peter Zijlstra > Cc: Steven Rostedt > Cc: linux-arm-kernel@lists.infradead.org Acked-by: Mathieu Poirier > > --- > drivers/hwtracing/coresight/coresight-etm4x.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > --- a/drivers/hwtracing/coresight/coresight-etm4x.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x.c > @@ -371,7 +371,7 @@ static void etm4_disable_sysfs(struct co > * after cpu online mask indicates the cpu is offline but before the > * DYING hotplug callback is serviced by the ETM driver. > */ > - get_online_cpus(); > + cpus_read_lock(); > spin_lock(&drvdata->spinlock); > > /* > @@ -381,7 +381,7 @@ static void etm4_disable_sysfs(struct co > smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1); > > spin_unlock(&drvdata->spinlock); > - put_online_cpus(); > + cpus_read_unlock(); > > dev_info(drvdata->dev, "ETM tracing disabled\n"); > } > @@ -982,7 +982,7 @@ static int etm4_probe(struct amba_device > > drvdata->cpu = pdata ? pdata->cpu : 0; > > - get_online_cpus(); > + cpus_read_lock(); > etmdrvdata[drvdata->cpu] = drvdata; > > if (smp_call_function_single(drvdata->cpu, > @@ -990,18 +990,18 @@ static int etm4_probe(struct amba_device > dev_err(dev, "ETM arch init failed\n"); > > if (!etm4_count++) { > - cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING, > - "arm/coresight4:starting", > - etm4_starting_cpu, etm4_dying_cpu); > - ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, > - "arm/coresight4:online", > - etm4_online_cpu, NULL); > + cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING, > + "arm/coresight4:starting", > + etm4_starting_cpu, etm4_dying_cpu); > + ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN, > + "arm/coresight4:online", > + etm4_online_cpu, NULL); > if (ret < 0) > goto err_arch_supported; > hp_online = ret; > } > > - put_online_cpus(); > + cpus_read_unlock(); > > if (etm4_arch_supported(drvdata->arch) == false) { > ret = -EINVAL; > >