From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 EF631C43381 for ; Tue, 12 Mar 2019 06:51:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE43C2147C for ; Tue, 12 Mar 2019 06:51:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727283AbfCLGv2 (ORCPT ); Tue, 12 Mar 2019 02:51:28 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:40190 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726218AbfCLGv1 (ORCPT ); Tue, 12 Mar 2019 02:51:27 -0400 Received: from svr-orw-mbx-03.mgc.mentorg.com ([147.34.90.203]) by relay1.mentorg.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-SHA384:256) id 1h3bFy-0007NL-7W from Jiada_Wang@mentor.com ; Mon, 11 Mar 2019 23:51:22 -0700 Received: from jiwang-OptiPlex-980.tokyo.mentorg.com (147.34.91.1) by svr-orw-mbx-03.mgc.mentorg.com (147.34.90.203) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Mon, 11 Mar 2019 23:51:18 -0700 From: Jiada Wang To: , , , , , CC: , , , , Subject: [PATCH 1/1] PM / Domains: Avoid a potential deadlock Date: Tue, 12 Mar 2019 15:51:28 +0900 Message-ID: <20190312065128.24994-1-jiada_wang@mentor.com> X-Mailer: git-send-email 2.19.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-ClientProxiedBy: SVR-ORW-MBX-09.mgc.mentorg.com (147.34.90.209) To svr-orw-mbx-03.mgc.mentorg.com (147.34.90.203) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Lockdep warns that prepare_lock and genpd->mlock can cause a deadlock the deadlock scenario is like following: First thread is probing cs2000 cs2000_probe() clk_register() __clk_core_init() clk_prepare_lock() ----> acquires prepare_lock cs2000_recalc_rate() i2c_smbus_read_byte_data() rcar_i2c_master_xfer() dma_request_chan() rcar_dmac_of_xlate() rcar_dmac_alloc_chan_resources() pm_runtime_get_sync() __pm_runtime_resume() rpm_resume() rpm_callback() genpd_runtime_resume() ----> acquires genpd->mlock Second thread is attaching any device to the same PM domain genpd_add_device() genpd_lock() ----> acquires genpd->mlock cpg_mssr_attach_dev() of_clk_get_from_provider() __of_clk_get_from_provider() __clk_create_clk() clk_prepare_lock() ----> acquires prepare_lock Since currently no PM provider access genpd's critical section in .attach_dev, and .detach_dev callbacks, so there is no need to protect these two callbacks with genpd->mlock. This patch avoids a potential deadlock by moving out .attach_dev and .detach_dev from genpd->mlock, so that genpd->mlock won't be held when prepare_lock is acquired in .attach_dev and .detach_dev Signed-off-by: Jiada Wang --- drivers/base/power/domain.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 500de1dee967..a00ca6b8117b 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -1467,12 +1467,12 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev, if (IS_ERR(gpd_data)) return PTR_ERR(gpd_data); - genpd_lock(genpd); - ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0; if (ret) goto out; + genpd_lock(genpd); + dev_pm_domain_set(dev, &genpd->domain); genpd->device_count++; @@ -1480,9 +1480,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev, list_add_tail(&gpd_data->base.list_node, &genpd->dev_list); - out: genpd_unlock(genpd); - + out: if (ret) genpd_free_dev_data(dev, gpd_data); else @@ -1531,15 +1530,15 @@ static int genpd_remove_device(struct generic_pm_domain *genpd, genpd->device_count--; genpd->max_off_time_changed = true; - if (genpd->detach_dev) - genpd->detach_dev(genpd, dev); - dev_pm_domain_set(dev, NULL); list_del_init(&pdd->list_node); genpd_unlock(genpd); + if (genpd->detach_dev) + genpd->detach_dev(genpd, dev); + genpd_free_dev_data(dev, gpd_data); return 0; -- 2.19.2 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiada Wang Subject: [PATCH 1/1] PM / Domains: Avoid a potential deadlock Date: Tue, 12 Mar 2019 15:51:28 +0900 Message-ID: <20190312065128.24994-1-jiada_wang@mentor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Sender: linux-kernel-owner@vger.kernel.org To: rjw@rjwysocki.net, khilman@kernel.org, ulf.hansson@linaro.org, len.brown@intel.com, pavel@ucw.cz, gregkh@linuxfoundation.org Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, kuninori.morimoto.gx@renesas.com, geert@linux-m68k.org, jiada_wang@mentor.com List-Id: linux-pm@vger.kernel.org Lockdep warns that prepare_lock and genpd->mlock can cause a deadlock the deadlock scenario is like following: First thread is probing cs2000 cs2000_probe() clk_register() __clk_core_init() clk_prepare_lock() ----> acquires prepare_lock cs2000_recalc_rate() i2c_smbus_read_byte_data() rcar_i2c_master_xfer() dma_request_chan() rcar_dmac_of_xlate() rcar_dmac_alloc_chan_resources() pm_runtime_get_sync() __pm_runtime_resume() rpm_resume() rpm_callback() genpd_runtime_resume() ----> acquires genpd->mlock Second thread is attaching any device to the same PM domain genpd_add_device() genpd_lock() ----> acquires genpd->mlock cpg_mssr_attach_dev() of_clk_get_from_provider() __of_clk_get_from_provider() __clk_create_clk() clk_prepare_lock() ----> acquires prepare_lock Since currently no PM provider access genpd's critical section in .attach_dev, and .detach_dev callbacks, so there is no need to protect these two callbacks with genpd->mlock. This patch avoids a potential deadlock by moving out .attach_dev and .detach_dev from genpd->mlock, so that genpd->mlock won't be held when prepare_lock is acquired in .attach_dev and .detach_dev Signed-off-by: Jiada Wang --- drivers/base/power/domain.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 500de1dee967..a00ca6b8117b 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -1467,12 +1467,12 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev, if (IS_ERR(gpd_data)) return PTR_ERR(gpd_data); - genpd_lock(genpd); - ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0; if (ret) goto out; + genpd_lock(genpd); + dev_pm_domain_set(dev, &genpd->domain); genpd->device_count++; @@ -1480,9 +1480,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev, list_add_tail(&gpd_data->base.list_node, &genpd->dev_list); - out: genpd_unlock(genpd); - + out: if (ret) genpd_free_dev_data(dev, gpd_data); else @@ -1531,15 +1530,15 @@ static int genpd_remove_device(struct generic_pm_domain *genpd, genpd->device_count--; genpd->max_off_time_changed = true; - if (genpd->detach_dev) - genpd->detach_dev(genpd, dev); - dev_pm_domain_set(dev, NULL); list_del_init(&pdd->list_node); genpd_unlock(genpd); + if (genpd->detach_dev) + genpd->detach_dev(genpd, dev); + genpd_free_dev_data(dev, gpd_data); return 0; -- 2.19.2