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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 D9484C10F0E for ; Thu, 18 Apr 2019 18:17:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABEEF20675 for ; Thu, 18 Apr 2019 18:17:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555611455; bh=bKqwVv9yjqHquJY/6k654Djzhp7VUy5HUN6yxtJ7BEw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=L+w2703ZUS73EH5rq/btKWVx3ZUFd7cvePN9mue9LnGkyGc4c5ue3Ly9Dg6hDgUS0 t/Ue9e7YUh/eu0EUUHk0O38iK8q69hdsLkkzLbnpvJflOdqRFKP6ZOT4keneU3iV7d SFL8DzetrM8WJXHHGYRqatsoeRLG2TXEKmJm4gCA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404274AbfDRSRe (ORCPT ); Thu, 18 Apr 2019 14:17:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:43458 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391686AbfDRSLR (ORCPT ); Thu, 18 Apr 2019 14:11:17 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 DC20520652; Thu, 18 Apr 2019 18:11:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555611076; bh=bKqwVv9yjqHquJY/6k654Djzhp7VUy5HUN6yxtJ7BEw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yTVVh9sk5qBu+CWpNT9DBityvZ+KvTwkZPGR2PM8YSAQ5aKqlp0DdDDyToDkWlafu iGWwZkQVhDSOiee7XlWrhyw0i9zNNu/ydbv004n+5cJ5T/vjhh1/2XkrTdh13H72Q2 rB6T4339mWyMwfsWPJcS2Eb7LUxjMrOlNU3tSm4A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiada Wang , Ulf Hansson , Geert Uytterhoeven , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 5.0 50/93] PM / Domains: Avoid a potential deadlock Date: Thu, 18 Apr 2019 19:57:28 +0200 Message-Id: <20190418160442.790170632@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190418160436.781762249@linuxfoundation.org> References: <20190418160436.781762249@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 2071ac985d37efe496782c34318dbead93beb02f ] 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 Reviewed-by: Ulf Hansson Tested-by: Geert Uytterhoeven Reviewed-by: Geert Uytterhoeven Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- 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; -- 2.19.1