From patchwork Tue Oct 27 13:49:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 312772 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1428DC388F9 for ; Tue, 27 Oct 2020 14:58:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B843A20780 for ; Tue, 27 Oct 2020 14:58:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603810690; bh=JkQPIbcA5besSeShAidqXjG0dMlW9ZyyeGO2Wb+eEFA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mOzUFTr6AtO89UHwezyMTLKNNJSSRfjR65tFsId66VS7ApczLvSTWXVrX/o4jTDIK ylkhutBwdbZMKaowNwJey55q3jQKjo1lxeDmm8j0Fdl6QTybCOD40howcTDKE662qo DOQMp1+/XzcEdPzA3K6AFtBMhGpwpy0pKfcP/iiQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763851AbgJ0O6J (ORCPT ); Tue, 27 Oct 2020 10:58:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:59264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1783324AbgJ0O6G (ORCPT ); Tue, 27 Oct 2020 10:58:06 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0C5BC20715; Tue, 27 Oct 2020 14:58:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603810685; bh=JkQPIbcA5besSeShAidqXjG0dMlW9ZyyeGO2Wb+eEFA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ka6Lca6kXb8BMDWrnbywrPnVA/wzfjpNG7Ik5CQWgmOKL8mUEU14PAUdfOfVVhFcc he8hSGdeLSAvFnU8dVvcZsAh/cAshA2g/+H5I/Jkb+afoFYXeD2ocHUYyfP7JpGDm2 TNN9aRhsUu9EpLrWEv5EiV0vjO4q569fbAhIth/Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Suzuki K Poulose , Stephen Boyd , Sai Prakash Ranjan , Mathieu Poirier , Sasha Levin Subject: [PATCH 5.8 228/633] coresight: etm4x: Fix etm4_count race by moving cpuhp callbacks to init Date: Tue, 27 Oct 2020 14:49:31 +0100 Message-Id: <20201027135533.375581738@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135522.655719020@linuxfoundation.org> References: <20201027135522.655719020@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sai Prakash Ranjan [ Upstream commit 2d1a8bfb61ec0177343e99ebd745e3e4ceb0d0d5 ] etm4_count keeps track of number of ETMv4 registered and on some systems, a race is observed on etm4_count variable which can lead to multiple calls to cpuhp_setup_state_nocalls_cpuslocked(). This function internally calls cpuhp_store_callbacks() which prevents multiple registrations of callbacks for a given state and due to this race, it returns -EBUSY leading to ETM probe failures like below. coresight-etm4x: probe of 7040000.etm failed with error -16 This race can easily be triggered with async probe by setting probe type as PROBE_PREFER_ASYNCHRONOUS and with ETM power management property "arm,coresight-loses-context-with-cpu". Prevent this race by moving cpuhp callbacks to etm driver init since the cpuhp callbacks doesn't have to depend on the etm4_count and can be once setup during driver init. Similarly we move cpu_pm notifier registration to driver init and completely remove etm4_count usage. Also now we can use non cpuslocked version of cpuhp callbacks with this movement. Fixes: 9b6a3f3633a5 ("coresight: etmv4: Fix CPU power management setup in probe() function") Fixes: 58eb457be028 ("hwtracing/coresight-etm4x: Convert to hotplug state machine") Suggested-by: Suzuki K Poulose Tested-by: Stephen Boyd Reviewed-by: Stephen Boyd Reviewed-by: Suzuki K Poulose Signed-off-by: Sai Prakash Ranjan Signed-off-by: Mathieu Poirier Link: https://lore.kernel.org/r/20200916191737.4001561-2-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/hwtracing/coresight/coresight-etm4x.c | 65 +++++++++---------- 1 file changed, 31 insertions(+), 34 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c index 6089c481f8f19..a970bd17edf8d 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.c +++ b/drivers/hwtracing/coresight/coresight-etm4x.c @@ -48,8 +48,6 @@ module_param(pm_save_enable, int, 0444); MODULE_PARM_DESC(pm_save_enable, "Save/restore state on power down: 1 = never, 2 = self-hosted"); -/* The number of ETMv4 currently registered */ -static int etm4_count; static struct etmv4_drvdata *etmdrvdata[NR_CPUS]; static void etm4_set_default_config(struct etmv4_config *config); static int etm4_set_event_filters(struct etmv4_drvdata *drvdata, @@ -1394,28 +1392,25 @@ static struct notifier_block etm4_cpu_pm_nb = { .notifier_call = etm4_cpu_pm_notify, }; -/* Setup PM. Called with cpus locked. Deals with error conditions and counts */ -static int etm4_pm_setup_cpuslocked(void) +/* Setup PM. Deals with error conditions and counts */ +static int __init etm4_pm_setup(void) { int ret; - if (etm4_count++) - return 0; - ret = cpu_pm_register_notifier(&etm4_cpu_pm_nb); if (ret) - goto reduce_count; + return ret; - ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING, - "arm/coresight4:starting", - etm4_starting_cpu, etm4_dying_cpu); + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING, + "arm/coresight4:starting", + etm4_starting_cpu, etm4_dying_cpu); if (ret) goto unregister_notifier; - ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN, - "arm/coresight4:online", - etm4_online_cpu, NULL); + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "arm/coresight4:online", + etm4_online_cpu, NULL); /* HP dyn state ID returned in ret on success */ if (ret > 0) { @@ -1424,21 +1419,15 @@ static int etm4_pm_setup_cpuslocked(void) } /* failed dyn state - remove others */ - cpuhp_remove_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING); + cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING); unregister_notifier: cpu_pm_unregister_notifier(&etm4_cpu_pm_nb); - -reduce_count: - --etm4_count; return ret; } -static void etm4_pm_clear(void) +static void __init etm4_pm_clear(void) { - if (--etm4_count != 0) - return; - cpu_pm_unregister_notifier(&etm4_cpu_pm_nb); cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING); if (hp_online) { @@ -1491,22 +1480,12 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) if (!desc.name) return -ENOMEM; - cpus_read_lock(); etmdrvdata[drvdata->cpu] = drvdata; if (smp_call_function_single(drvdata->cpu, etm4_init_arch_data, drvdata, 1)) dev_err(dev, "ETM arch init failed\n"); - ret = etm4_pm_setup_cpuslocked(); - cpus_read_unlock(); - - /* etm4_pm_setup_cpuslocked() does its own cleanup - exit on error */ - if (ret) { - etmdrvdata[drvdata->cpu] = NULL; - return ret; - } - if (etm4_arch_supported(drvdata->arch) == false) { ret = -EINVAL; goto err_arch_supported; @@ -1553,7 +1532,6 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) err_arch_supported: etmdrvdata[drvdata->cpu] = NULL; - etm4_pm_clear(); return ret; } @@ -1591,4 +1569,23 @@ static struct amba_driver etm4x_driver = { .probe = etm4_probe, .id_table = etm4_ids, }; -builtin_amba_driver(etm4x_driver); + +static int __init etm4x_init(void) +{ + int ret; + + ret = etm4_pm_setup(); + + /* etm4_pm_setup() does its own cleanup - exit on error */ + if (ret) + return ret; + + ret = amba_driver_register(&etm4x_driver); + if (ret) { + pr_err("Error registering etm4x driver\n"); + etm4_pm_clear(); + } + + return ret; +} +device_initcall(etm4x_init);